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Interactive Cardiovascular and Thoracic Surgery 1:16-22(2002)
© 2002 European Association of Cardio-Thoracic Surgery

Work in progress report

Endothelial function after prolonged coronary artery oxygen persufflation in a rabbit model of heart preservation

S. Kunzea, S. Jeschkeit-Schubbertb, S. Dahnkenb, J.H. Fischerb and S. Herziga,*

a Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
b Institute for Experimental Medicine, University of Cologne, Cologne, Germany

* Corresponding author. Tel.: +49-221-478-6064; fax: +49-221-478-5022
stefan.herzig{at}uni-koeln.de

Received January 11, 2002; received in revised form April 18, 2002; accepted May 1, 2002


   Abstract
Top
 Abstract
1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 Acknowledgements
 References
 
Coronary oxygen persufflation may serve as a means to improve storage conditions and organ preservation time for cardiac transplantation. We examined whether coronary oxygen persufflation and prolonged preservation time alter the endothelium-dependent relaxation of isolated coronary arteries. Isolated rabbit hearts were subjected to four different protocols: control (no preservation), 3 h cold storage in Bretschneider's solution, 18 h cold storage in Bretschneider's or University of Wisconsin solution, combined with coronary oxygen persufflation. After 2 h parabiotic reperfusion, intramural segments of coronary arteries were isolated and isometric tension was recorded using a small-vessel myograph. Endothelial function was examined using carbachol and substance P, applied after vessel constriction using high (30 mmol/l) K+ or U 46.619, a thromboxane receptor agonist. In another series, coronary flow was measured after Bretschneider's ±18 h coronary oxygen persufflation, or in freshly isolated, retrogradely perfused Langendorff hearts. Flow responses to substance P, acetylcholine or bradykinin were recorded. In saline-reperfused intact hearts no change in the normal effects of endothelium-dependent relaxants was detected after 18 h, irrespective of coronary oxygen persufflation. However, after isolation of the resistance vessels endothelium-dependent relaxation was abolished after long-term preservation and persufflation. Similar results were obtained after mechanical removal of the endothelium using control hearts. Short-term preservation without persufflation resulted in relaxations similar to those in non-preserved control hearts. Long-term preservation of rabbit heart including coronary oxygen persufflation results in unchanged endothelium-dependent relaxation in intact heart, but abolishes the endothelium-dependent relaxation after isolation of the vessels.

Key Words: Coronary oxygen persufflation; Rabbit heart; Endothelium; Coronary relaxation


   1. Introduction
Top
 Abstract
 1. Introduction
2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 Acknowledgements
 References
 
Clinical heart transplantation depends on donor hearts preserved for 3–4 h at most [1], using current hypothermic preservation methods. Otherwise, insufficient functional recovery and irreversible organ damage would result.

One of the numerous methods developed to improve long-time storage is persufflation with gaseous oxygen. Already mentioned in 1902 [2], this method was experimentally shown to be useful for renal [3] and liver [4] transplantation. Rolles et al. [5] performed the first clinical trial on kidney transplantation. Animal studies for the use in heart transplantation showed excellent results especially when coronary oxygen persufflation (COP) was combined with use of a modified Bretschneider's (histidine-tryptophan-ketoglutarate, HTK) solution. After 14 h of preservation, the recipient's circulation was working without support of catecholamines [6], and isolated donor hearts were functionally equivalent to hearts after conventional short-term storage [7].

However, the contact of gaseous oxygen with the vascular wall is highly unphysiologic; the persufflation with air is even used experimentally to remove the endothelium [8]. Thus, the question arises whether functional damage of the endothelium is a consequence of this preservation method, as the importance of protecting the endothelium during organ preservation of the heart seems well accepted [9]. For the large epicardial coronary arteries of pig hearts, normal endothelial-derived vascular relaxation was preserved 3 h to 7 days after up to 14 h COP [10] and after a preceding period of 16 min normothermic ischemia in a non-heart-beating donor [11].

However, the regulation of blood flow is to the greater part due to resistance vessels. It is modulated by the endothelium through releasing vasoactive substances acting on vascular smooth muscle cells. Especially with freshly transplanted hearts devoid of autonomic neuronal input, the endothelium should play an important role in regulating the coronary flow and the perfusion pressure.

Thus, the present study was designed to investigate coronary endothelial function using two experimental settings. First, we assessed the effect of COP (along with long-term storage) on total coronary resistance in whole hearts. Second, to examine the resistance vascular function in closer detail, we isolated and examined intramural resistance vessels after 18 h of preservation and COP, followed by parabiotic blood reperfusion. Two preservation solutions were tested. We compared the results with isolated arteries from fresh hearts with and without mechanical removal of the endothelium, and with a protocol mimicking the currently used short-term preservation procedure. Our data demonstrate that prolonged COP preserves endothelium-dependent relaxation of resistance vessels in the intact heart, but results in abolished endothelium-dependent relaxation after isolation of the vessels.


   2. Materials and methods
Top
 Abstract
 1. Introduction
 2. Materials and methods
3. Results
 4. Discussion
 Appendix A
 Acknowledgements
 References
 
Animals were housed, fed, and handled in compliance with German legislation on protection of animals and the Guide for the Care and Use of Laboratory Animals published by the NIH (Publication 86-23, revised 1996).

2.1. Preservation and reperfusion

Hearts of male New Zealand white rabbits (body weight approximately 2.5 kg) were explanted under barbiturate anesthesia after intravenous heparinization (2500 U) and median thoracotomy. Cardioplegic arrest was induced by flush perfusion with cold (0–1 °C) preservation solution started in situ via an aortic catheter; this was accompanied by external cooling of the heart with cold preservation solution.

After cardioplegic arrest the hearts were quickly removed and were perfused via an aortic catheter with preservation solution. The perfusion pressure was 75 mmHg for 5 min in the University of Wisconsin solution (UWG) group, and 75 mmHg for 1 min in the HTK group, followed by reduction to 50 mmHg for another 9 min, according to the application rules of this solution. Two preservation solutions were used: University of Wisconsin solution, modified by adding 3 mmol/l reduced glutathione (UWG, NPBI, The Netherlands) and Bretschneider's histidine-tryptophan-ketoglutarate solution (HTK, Custodiol®, Dr. F. Köhler Chemie GmbH, Germany). Both solutions were filtered (pore size: 0.45 µm) before being administered. There were two long-term preserved groups, which were both stored after flushing for 18 h in either UWG or HTK. During this period, gaseous oxygen was administered via an aortic catheter, called COP. The persufflation pressure was 35–50 mmHg, resulting in a coronary gas flow of 3–12 ml/min. In the following these groups are named HTK+18 h COP, and UWG+18 h COP, respectively.

As the reference preservation method, another group was simply stored in HTK for 3 h, simulating the usual clinical procedure (HTK 3 h). During storage, the preservation solution was maintained at 0–1 °C by keeping the storage container in iced water. In each of the three groups, the temperature was raised to 25 °C during the last 30 min of storing, thereby simulating the warm up period during transplantation.

Reperfusion (Langendorff technique) was performed parabiotically at 37 °C for 80 min after an initial warm reflush. This 10 min reflush was done using modified Krebs–Henseleit buffer with a reduced calcium ion content of 50 µmol/l at a pressure of 50 mmHg. Calcium ion content was raised to 1.8 mmol/l at the 8th minute. Then, for parabiotic reperfusion arterial blood of an anesthetized rabbit (pentobarbitone anesthesia) was directed by a short silicone catheter from the carotid artery into the aorta of the graft. The blood returned from the pulmonary artery into the jugular vein of the host. During the whole reperfusion period, the graft was maintained at 37 °C in a water-jacketed constant temperature chamber. Adenosine at a concentration of 0.015 mmol/l was added up to the 60th minute. During this time, ventricular functional parameters were measured.

At the end of reperfusion, the apex of the heart was immediately frozen in liquid nitrogen using the freeze-stop technique and cut off with a scalpel. The coronary arteries of the heart base were flushed with 20 ml of Tyrode's solution (see below) and the heart base was put in a container filled with preoxygenated Tyrode's at room temperature for transportation (5 min).

2.2. Non-preserved control groups

After the serving for this parabiotic reperfusion, the heart of the host was removed to obtain arterial segments of a non-preserved control group (control). The coronary arteries were flushed with Tyrode's buffer via an aortic catheter to remove the blood. It was also stored in Tyrode's for transportation (5 min). The arteries from these hearts served as controls without preservation. In some of the arteries, the endothelium was mechanically destroyed at a later stage (see below).

2.3. Preparation of coronary artery segments

The heart base was put in a silicon-covered glass petri dish. Throughout the preparation procedure, the tissue was continuously bathed in warm Tyrode's buffer and gassed with carbogen (95% O2, 5% CO2). The visceral pericardium of the left ventricle was removed, and the subepicardial vasculature was exposed by blunt dissection. Third generation branches of the left coronary artery were isolated and freed of the surrounding tissue. Artery segment preparations (1.3–2 mm long) were mounted on two 40 µm stainless steel wires in an isometric double myograph system [12] by fixing one of the wires to a force transducer and the second wire to a length-displacement device. Great care was taken in the dissection of the arteries to avoid damage to their intimal surface. Usually one or two segments from each heart were used.

2.4. Measurement of isometric force

The contraction of vessels is dependent on the degree of their passive tension. Since the geometry of investigated vessels differed, it was essential to set them to a normalized passive tension. Therefore, the resting tension-internal circumference relationship was determined for each artery as described by Mulvany and Halpern [12] and McPherson [13]. Based on these data, the internal circumference of the arterial segment at a transmural pressure of 100 mmHg (L100) was calculated. Each preparation was then fixed at a normalized internal circumference of 0.9xL100. At this level of stretching, the maximum active wall tension is obtained [12].

2.5. Experimental protocol in isolated arteries

After an arterial segment was set to its normalized tension, a 15 min equilibration period followed to obtain a stable baseline. Then the preparations were repeatedly exposed to Tyrode's solution containing 30 mmol/l K+ ions (K+-Tyrode's) until reproducible contractions were obtained (two or three times). When a plateau was reached, carbachol was added cumulatively to the organ bath (10–7 to 10–5 mol/l). Following a 30 min washout period, the preparations were exposed to U 46.619 (3x10–7 mol/l). After 5 min carbachol (10–6 mol/l) was added. The effect, once established, was then promptly and fully reversed by adding atropine (10–5 mol/l). Then the response to substance P (10–5 mol/l) was tested. Afterwards, the bath solution was changed several times with Tyrode's. The preparations were again constricted using K+-Tyrode's. Finally, sodium nitroprusside (10–4 mol/l) was added in order to check for endothelium-independent, NO-mediated relaxation.

In some of the control group arteries, after testing the ability to contract with K+-Tyrode's and eliciting a relaxation with carbachol (10–6 mol/l), the endothelium was removed by rubbing a human hair gently at its inner surface. Then, another contraction with K+-Tyrode's was elicited. In this group (control w/o endothelium) the same experiments were performed as with the other groups.

All experiments were performed under continuous gassing of the bath chamber with carbogen (95% O2, 5% CO2). The temperature was maintained at 37±0.5 °C.

2.6. Coronary flow measurements in intact hearts

In another series of experiments, control hearts were freshly removed from donor animals, subjected to cardioplegic arrest, and reperfused with Krebs–Henseleit solution after mounting in a Langendorff apparatus (retrograde perfusion). Control hearts and preparations exposed to HTK+18 h COP, or stored in HTK for 18 h without COP, were subjected to saline (re-)perfusion as described above, but instead of parabiotic reperfusion, Langendorff perfusion with Krebs–Henseleit solution was done. After stabilization under constant pressure (50 mmHg), 2 min continuous infusions of various vasorelaxant agents were performed (see Table 1), and the resulting changes in coronary flow were recorded using an ultrasonic transit time flowmeter.


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  		Table 1 Drug-induced increase in coronary flow observed under constant pressure perfused in Langendorff heartsa

 
2.7. Drugs and solutions

Tyrode's solution (mmol/l): NaCl 137, KCl 2.7, CaCl2 1.8, MgCl2 1.1, NaHCO3 12, NaH2PO4 0.21, glucose 5.5.

K+-Tyrode's (mmol/l): NaCl 109.7, KCl 30, CaCl2 1.8, MgCl2 1.1, NaHCO3 12, NaH2PO4 0.21, glucose 5.5.

Krebs–Henseleit solution (mmol/l): NaCl 118.1, KCl 4.7, CaCl2 1.8 (initially 0.05), MgSO4 1.1, NaHCO3 25, KH2PO4 1.2, glucose 11.1, insulin 1 IU/l.

Only for preceding the parabiotic reperfusion this solution contained initially in addition: adenosine 0.015, uric acid 1.0. The following compounds were used: acetylcholine, bradykinin, carbachol, U 46.619 (9,11-dideoxy-11{alpha},9{alpha}-epoxymethano-prostaglandine F2{alpha}), atropine, substance P, sodium nitroprusside (all from Sigma, Germany). U 46.619 was dissolved as 10–4 mol/l stock solution in ethanol. Aliquots were stored protected from light. Sodium nitroprusside was dissolved in a 10 mmol/l aqueous stock solution for later use at final concentrations of 10–4 or 10–6 mol/l in isolated arteries and whole hearts, respectively. The stock solutions (U 46.619, sodium nitroprusside) were stored at –20 °C before daily use. All other drugs were freshly dissolved in distilled water at appropriate concentrations.

2.8. Statistics

Results are expressed as the mean±SEM, with n indicating the number of arterial segments or reperfused hearts. Contractions were determined as differences between constant baseline before contraction and stabile contraction maximum. Changes in tension after adding vasoactive substances were determined as differences between contraction plateau before drug addition and the maximum decrease or increase after drug, respectively; vasoconstriction is indicated in absolute values and in percent of the response of the same preparation to K+-Tyrode's where applicable. Relaxations are indicated as percent change of force, relative to the preceding constriction. Throughout, relaxations are indicated as negative values, and contractions as positive values. Maximal coronary flow changes during the infusion period of each substance were calculated in percent of the flow immediately before the start of infusion.

The significance of differences between the treated groups and control groups was tested using a two-tailed t-test (Welch). Differences were considered significant when P was less than 0.05 (a statistic difference referring to the control group is indicated by an asterisk).


   3. Results
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
4. Discussion
 Appendix A
 Acknowledgements
 References
 
3.1. Coronary flow in intact hearts after COP

Coronary flow as measured in intact hearts could be increased during Krebs–Henseleit reperfusion by various agents after HTK+18 h COP (Table 1). The increase in flow by the endothelium-dependent agonists (substance P, acetylcholine and bradykinin) was indistinguishable from freshly isolated hearts, and from the values obtained with sodium nitroprusside. When hearts were simply stored in HTK without COP, regulation of coronary flow was preserved in a very similar manner. However, contractile force (measured as isovolumetric dp/dtmax), which amounted to 1270 mmHg/s on average in controls and 1230 mmHg/s in HTK+18 h COP preserved hearts was severely impaired in hearts preserved for 18 h without COP (by 33%).

To examine whether the entire cascade of endothelium-dependent relaxation remained intact in resistance arteries after COP, the following experiments in isolated vessels were performed.

3.2. Internal diameter of the isolated vessels

The coronary artery segments had the following normalized internal diameters: control (), 325±36 µm; control w/o endothelium (), 456±48 µm; HTK 3 h (), 356±25 µm; HTK+18 h COP (), 325±16 µm; UWG+18 h COP (), 399±22 µm.

3.3. Contractile responses

The contractile responses to K+-Tyrode's (30 mmol/l K+) and U 46.619 did not differ significantly among all groups. The following forces were measured as a response to K+-Tyrode's: control, 4.4±0.9 mN; control w/o endothelium, 6.2±1.6 mN; HTK 3 h, 7.2±1.1 mN; HTK+18 h COP, 5.0±1.2 mN; UWG+18 h COP, 5.8±1.1 mN. U 46.619 elicited stronger contractions in all groups. The following values of contractile force were measured (in parentheses: relative to K+-Tyrode's contraction): control, 6.2±1.2 mN (151±21%); control w/o endothelium, 8.3±2.0 mN (154±10%); HTK 3 h, 8.9±1.0 mN (146±35%); HTK+18 h COP, 6.3±1.5 mN (146±13%); UWG+18 h COP, 7.2±1.9 mN (135±8%). In summary, long-term storage with COP neither impeded nor increased the contractile response of the arteries caused by depolarization or agonist.

The K+-evoked contractions obtained at the end of the protocol were more pronounced than the first contraction in most cases. In some experiments the previous contraction due to U 46.619 could not be washed out completely (mostly within the long-time conserved groups), resulting in a smaller degree of further contraction in response to K+-Tyrode's. Relative to the first K+-dependent contraction the following values were obtained (n as in first K+-induced contraction): control, 137±27%; control w/o endothelium, 130±14%; HTK 3 h, 118±15%; HTK+18 h COP, 76±15%; UWG+18 h COP, 92±5%.

3.4. Endothelium-dependent relaxation by carbachol

Carbachol induced rapid concentration-dependent relaxations in the arterial segments of the control and the HTK 3 h group (see Fig. 1, top). The segments of the long-time preserved groups and the group without endothelium showed either no change or a small increase in tension (see Fig. 1, bottom). The data obtained with carbachol indicate that abolition of the endothelium-dependent relaxation occurs irrespective of agonist concentration. They are summarized in Table 2. Similar reactions were found with carbachol added to a U 46.619-induced contraction. These results are displayed in Fig. 2B.



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  		Fig. 1 Representative force recordings illustrating the first part of the experimental protocol. Upper trace: control preparation. Lower trace: preparation after UWG+18 h COP.

 

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  		Table 2 Carbachol effects in arterial segments precontracted by K+-Tyrode's (30 mmol/l K+)a

 


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  		Fig. 2 Change in tension after substance P (A), or carbachol (B) after precontraction by U 46.619 (3x10–7mol/l). Box plot: {blacksquare} mean; horizontal bars indicate minimum, 25th percentile, median, 75th percentile, maximum. Asterisks indicate compared to control group.

 
3.5. Substance P

Substance P induced rapid relaxations in control preparations and in arteries obtained after short-term preservation. The effects were more prominent compared to relaxation exerted by carbachol. Again, endothelium-denuded arteries and arteries prepared after long-term preservation with COP did not show any vasorelaxant response. Changes in tension are displayed in Fig. 2A.

3.6. Endothelium-independent relaxation by sodium nitroprusside

To examine the possibility that the smooth muscle cells are directly impaired in their ability to relax, the responsiveness to a high, saturating concentration of sodium nitroprusside, a donor of NO, was tested. All groups showed rapid relaxations: control, –80±5%; control w/o endothelium, –93±8%; HTK 3 h, –88±9%; HTK+18 h COP, –134±12%; UWG+18 h COP, –113±7%. The responses of the long-time preserved groups were stronger than the others, although this did not turn out to be significant. This may be explained by the fact that especially in these groups the U 46.619 contraction could not be reversed completely, as described above.

In summary, independent of the agent used to check contraction (K+, U 46.619) or endothelium-dependent relaxation (carbachol, substance P), in isolated vessels long-term preservation with COP led to a response indicative of the absence of a functional endothelium.


   4. Discussion
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
Appendix A
 Acknowledgements
 References
 
To investigate endothelium-mediated relaxations we used two different widely used vasodilators: carbachol and substance P. Both substances act by the release of endothelium-derived relaxing factor (EDRF) [14], first described with acetylcholine by Furchgott and Zawadzki [15]. In addition, both substances stimulate the release of endothelium-derived hyperpolarizing factor (EDHF), a substance not yet fully identified [16]. Our study demonstrates profound changes in vascular reactivity to different substances that elicit endothelium-dependent relaxations. The relaxant responses to carbachol and substance P in the segment preparations of the COP groups and the group without endothelium were entirely abolished. Numerically, these endothelium-dependent responses after COP were significantly different from the responses of the control and the HTK 3 h group. This effect is not likely due to a mechanism at the level of the vascular smooth muscle cell. COP did not affect contractile response to high K+ or the thromboxane antagonist, U 46.619. Furthermore, all preparations were able to relax nearly completely after addition of a high concentration of a donor of NO, sodium nitroprusside.

What are the reasons for abolition of endothelial function in the present study? To examine the possible influence of a deterioration of the surrounding working myocardium in the preserved hearts, ventricular contractile function was measured during blood reperfusion: left ventricular maximum dp/dt of the long-time preserved groups under parabiotic reperfusion amounted to 560±59 mmHg/s (HTK+18 h COP), and 629±49 mmHg/s (UWG+18 h COP), respectively. These values were lower than those obtained with hearts perfused with saline solution without preservation or after HTK+18 h COP (1270 or 1230 mmHg/s, respectively). However, diminished contractile function is not necessarily associated with endothelial dysfunction, given the 860±48 mmHg/s found with the HTK 3 h group, where relaxation remained intact. Thus, given that contractile function of long-term persufflated hearts was not well preserved in our study, this effect was likely due to parabiotic blood reperfusion rather than long-term storage or COP. Interestingly, Kuhn-Regnier et al. [7] found similar values of left ventricular dp/dtmax after 14 h of persufflation using a modified HKT in pigs, compared to 3 h cold storage in HTK. It remains to be tested whether this difference to our results is due to time of persufflation, their modification of HTK composition, or the animal species chosen. The same group did not find evidence for a functional deterioration of large epicardial coronary arteries in pig [11].

Of note, our intact rabbit hearts after 18 h COP in HTK demonstrated a normal endothelial-dependent increase in coronary flow during 2 h of Langendorff-type reperfusion with Krebs–Henseleit solution. Exposure to substance P, acetylcholine, or bradykinin revealed no difference against non-persufflated hearts, or against relaxation by a low concentration of sodium nitroprusside. The most straightforward explanation might be that the COP protocol does not destroy endothelial per se, but in combination with the following surgical dissection of the arteries. COP may thus render endothelial cells susceptible to mechanical damage during vessel isolation. Alternatively, relaxation of resistance vessels in the whole heart may have been caused by the release of endothelial factors from uninjured, more proximal parts of the coronary vasculature. Furthermore, we have no definite proof that the isolated vessels examined here in detail do contribute predominantly to coronary resistance under constant pressure. Finally, one has to consider a number of other differences between the two methods used to determine endothelium-dependent vasorelaxation (use of agonist, isometric versus isobaric recording).

The following mechanisms, alone or in combination, might lead to the damage in isolated vessels: 18 h of contact with the preservation solutions HTK or UWG, 18 h of hypothermia, or 18 h of exposure to gaseous oxygen might lead to structural alterations or a higher vulnerability of the resistance vessels. Our experiments reveal that the damage is not elicited by the reperfusion period, because no alterations were seen in the HTK 3 h group. The endothelial damage in isolated vessels therefore must be due to the long (>> 3 h) duration of the storage, the storage solution, the hypothermia, or to the persufflation. Kevelaitis et al. [17] recorded endothelial damage of intramyocardial rat coronary arteries after 30 h of ischemia. He and Yang [18] found an impairment of bradykinin-induced relaxation of pig epicardial coronaries after 4 h of UW storage, but another study [19] describes maintained relaxation to acetylcholine of dog epicardial arteries after 24 h storage in UW solution.

It seems logical to further examine the pathogenic role of oxygen persufflation by studying arteries after short-term (3 h) preservation and COP. But COP when used for a storage period of only 3 h would not offer any benefit compared to routine practice. Conversely, it made little sense to us to study isolated vessels after 18 h storage without COP, given the poor myocardial contractile function under those conditions even under saline reperfusion. Thus, all these experiments seem worthwhile on conceptual grounds. However, we did not include them in this study because they were not part of our research question, and the results would be of no major clinical interest.

According to our data, patients who would be transplanted with a persufflated heart preserved for 18 h might have to deal with a higher vulnerability of the resistance vessels. A clinical trial by Hanet et al. [20] shows that after heart transplantation, patients showed maintained endothelium-derived vasodilation 12 months later. Cocks and Angus [21] highlighted the importance of an intact endothelium for situations encountering high catecholamine levels. Finally, endothelial dysfunction has been proposed as a pathogenic mechanism for coronary allograft vasculopathy [22,23], one of the main causes of death within the first year after cardiac transplantation [24].

In conclusion, prolonged COP does not impede endothelium-dependent coronary relaxation as determined in whole heart. However, it leads to abolition of endothelium-dependent coronary relaxation after isolation of arterial segments in a rabbit model. This suggests an increase in mechanical vulnerability of coronary resistance vessels by COP. Future experiments should address whether this problem might become clinically relevant by long-term examinations of microvascular and myocardial morphology and function of allografts in suitable animal models in vivo.


   Appendix A
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
Acknowledgements
 References
 
ICVTS on-line discussion

Author: Dr. Antonio Corno, Cardiovascular Surgery, Centre Hospitalier Universitaire Vaudois, 46 rue Bugnon, Lausanne, Switzerland

Date: 12-Aug-2002 15:21

Message: The authors should take into consideration two important points:

(i) In Materials and Methods there is no indication on the oxygen content in the Krebs-Henseleit buffer, used as reperfusion solution. After a prolonged ischemic period, as in this research protocol, the modalities of reperfusion, including the oxygen content, are relevant with regard to the potential endothelial damages.

(ii) In the discussion there is no mention of the fact that the initial reperfusion has been performed with Krebs-Henseleit buffer, therefore with a crystalloid solution. With this type of acellular reperfusion it is impossible to evaluate all the potential negative effects due to the presence of leokocytes in the reperfusion medium, particularly after a prolonged ischemic period.


   Acknowledgements
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 Acknowledgements
References
 
Part of this study was supported by the Köln-Fortune Programme of the Medical Faculty, University of Cologne.

PII: S156992930200004X


   References
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 Acknowledgements
 References
 

  1. Reichenspurner H, Russ C, Uberfuhr P, Nollert G, Schluter A, Reichart B, Klovekorn WP, Schuler S, Hetzer R, Brett W. Myocardial preservation using HTK solution for heart transplantation. A multicenter study. Eur J Cardiothorac Surg. 1993;7:414–419[Abstract]
  2. Magnus R. Die Taetigkeit des ueberlebenden Saeugetierherzens bei Durchstroemung mit Gasen. Arch Exp Path Pharmakol. 1902;47:200[CrossRef]
  3. Fischer JH, Czerniak A, Hauer U, Isselhard W. A new simple method for optimal storage of ischemically damaged kidneys. Transplantation. 1978;25:43–49[Medline]
  4. Fischer JH, Fuhs M, Miyata M, Isselhard W. Hypothermic liver preservation using different flush solutions and retrograde oxygen persufflation. Eur J Surg. 1980;12(Suppl 1):19
  5. Rolles K, Foreman J, Pegg DE. A pilot clinical study of retrograde oxygen persufflation in renal preservation. Transplantation. 1989;48:339–342[Medline]
  6. Fischer JH, Kuhn-Regnier F, Jeschkeit S, Switkowski R, Bardakcioglu O, Sobottke R, de Vivie ER. Excellent recovery after prolonged heart storage by preservation with coronary oxygen persufflation: orthotopic pig heart transplantations after 14-hr storage. Transplantation. 1998;66:1450–1459[CrossRef][Medline]
  7. Kuhn-Regnier F, Fischer JH, Jeschkeit S, Switkowski R, Bardakcioglu O, Sobottke R, de Vivie ER. Coronary oxygen persufflation combined with HTK cardioplegia prolongs the preservation time in heart transplantation. Eur J Cardiothorac Surg. 2000;17:71–76[Abstract/Free Full Text]
  8. Guyton JR, Dao DT, Lindsay KL. Endothelial denudation and myointimal thickening in the rat carotid artery induced by the passage of bubbles. Exp Mol Pathol. 1984;40:340–348[CrossRef][Medline]
  9. Stoica SC, Satchithananda DK, Dunning J, Large SR. Two-decade analysis of cardiac storage for transplantation. Eur J Cardiothorac Surg. 2001;20:792–798[Abstract/Free Full Text]
  10. Jeschkeit S, Kuhn-Régnier F, Dagtekin O, Fischer JH. Endothelial function after 14 hr preservation using coronary oxygen persufflation (COP) and transplantation in pigs. Basic Res Cardiol. 1999;94:347
  11. Fischer JH, Funcke C, Jeschkeit-Schubbert S, Yotsumoto G, Kuhn-Régnier F. Coronary endothelial function in heart grafts of non-heart-beating donors (NHBD) after 3 hr hypothermic COP-preservation and orthotopic transplantation in pigs. Eur Surg Res. 2001;33:130–131
  12. Mulvany MJ, Halpern W. Contractile properties of small arterial resistance vessels in spontaneously hypertensive and normotensive rats. Circ Res. 1977;41:19–26[Free Full Text]
  13. McPherson GA. Assessing vascular reactivity of arteries in the small vessel myograph. Clin Exp Pharmacol Physiol. 1992;19:815–825[Medline]
  14. Moncada S, Palmer RM, Higgs EA. Nitric oxide: physiology, pathophysiology, and pharmacology. Pharmacol Rev. 1991;43:109–142[Medline]
  15. Furchgott RF, Zawadzki JV. The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature. 1980;288:373–376[CrossRef][Medline]
  16. Tanaka Y, Kaneko H, Tanaka H, Shigenobu K. Pharmacologic characteristics of non-prostanoid, non-nitric oxide mediated and endothelium-dependent relaxation of guinea-pig aorta in response to substance P. Res Commun Mol Pathol Pharmacol. 1999;103:65–81[Medline]
  17. Kevelaitis E, Nyborg NC, Menasche P. Coronary endothelial dysfunction of isolated hearts subjected to prolonged cold storage: patterns and contributing factors. J Heart Lung Transplant. 1999;18:239–247[CrossRef][Medline]
  18. He GW, Yang CQ. Impaired endothelium-derived hyperpolarizing factor-mediated relaxation in coronary arteries by cold storage with University of Wisconsin solution. J Thorac Cardiovasc Surg. 1998;116:122–130[Abstract/Free Full Text]
  19. Sorajja P, Cabel DG, Schaff HV. Hypothermic storage with University of Wisconsin solution preserves endothelial and vascular smooth-muscle function. Circulation. 1997;96(Suppl):II297–II303
  20. Hanet C, Evrat P, Jaquet L, Goenen M, Robert A. Flow-mediated vasodilator response to tachycardia of epicardial coronary arteries is preserved in heart transplant recipients. Circulation. 1993;88(Suppl):II257–II262[Medline]
  21. Cocks TM, Angus JA. Endothelium-dependent relaxation of coronary arteries by noradrenaline and serotonin. Nature. 1983;305:627–629[CrossRef][Medline]
  22. Day JD, Rayburn BK, Gaudin PB, Baldwin WM 3rd, Lowenstein CJ, Kasper EK, Baughman KL, Baumgartner WA, Hutchins GM, Hruban RH. Cardiac allograft vasculopathy: the central pathogenic role of ischemia-induced endothelial cell injury. J Heart Lung Transplant. 1995;14:S142–S149[Medline]
  23. Davis SF, Yeung AC, Meredith IT, Charbonneau F, Ganz P, Selwyn AP, Anderson TJ. Early endothelial dysfunction predicts the development of transplant coronary artery disease at 1 year posttransplant. Circulation. 1996;93:457–462[Abstract/Free Full Text]
  24. Hosenpud JD, Bennett LE, Keck BM, Boucek MM, Novick RJ. The Registry of the International Society for Heart and Lung Transplantation: seventeenth official report-2000. J Heart Lung Transplant. 2000;19:909–931[CrossRef][Medline]




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