2-APB protects against liver ischemia-reperfusion injury by reducing cellular and mitochondrial calcium uptake.

Ischemia-reperfusion (I/R) injury is a commonly encountered clinical problem in liver surgery and transplantation. The pathogenesis of I/R injury is multifactorial, but mitochondrial Ca(2+) overload plays a central role. We have previously defined a novel pathway for mitochondrial Ca(2+) handling and now further characterize this pathway and investigate a novel Ca(2+)-channel inhibitor, 2-aminoethoxydiphenyl borate (2-APB), for preventing hepatic I/R injury. The effect of 2-APB on cellular and mitochondrial Ca(2+) uptake was evaluated in vitro by using (45)Ca(2+). Subsequently, 2-APB (2 mg/kg) or vehicle was injected into the portal vein of anesthetized rats either before or following 1 h of inflow occlusion to 70% of the liver. After 3 h of reperfusion, liver injury was assessed enzymatically and histologically. Hep G2 cells transfected with green fluorescent protein-tagged cytochrome c were used to evaluate mitochondrial permeability. 2-APB dose-dependently blocked Ca(2+) uptake in isolated liver mitochondria and reduced cellular Ca(2+) accumulation in Hep G2 cells. In vivo I/R increased liver enzymes 10-fold, and 2-APB prevented this when administered pre- or postischemia. 2-APB significantly reduced cellular damage determined by hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling staining of liver tissue. In vitro I/R caused a dissociation between cytochrome c and mitochondria in Hep G2 cells that was prevented by administration of 2-APB. These data further establish the role of cellular Ca(2+) uptake and subsequent mitochondrial Ca(2+) overload in I/R injury and identify 2-APB as a novel pharmacological inhibitor of liver I/R injury even when administered following a prolonged ischemic insult.

Interspecies differences in hepatic Ca(2+)-ATPase activity and the effect of cold preservation on porcine liver Ca(2+)-ATPase function.

The accumulation of intracellular calcium ([Ca(2+)](i)) caused by ischemia-reperfusion during liver transplantation has been implicated as a factor leading to primary graft nonfunction. Plasma membrane (PM) and endoplasmic reticulum (ER) Ca(2+)-adenosinetriphosphatases (ATPases) are the primary transporters that maintain [Ca(2+)](i) homeostasis in the liver. We hypothesized that the porcine liver is better than the rat liver as a model for the study of human liver Ca(2+)-ATPase activity. We also hypothesized that cold preservation would depress Ca(2+)-ATPase activity in the porcine liver. Pig and rat livers were harvested, and human liver samples were obtained from surgical resection specimens. All were preserved with University of Wisconsin solution, and porcine livers were also preserved on ice for 2 to 18 hours. Ca(2+)-ATPase activity was measured after incubation with (45)Ca(2+) and adenosine triphosphate in the presence of specific Ca(2+)-ATPase inhibitors. Porcine PM and ER Ca(2+)-ATPase activities were 0.47 +/- 0.03 and 1.57 +/- 0.10 nmol of Ca(2+)/mg of protein/min, respectively. This was not significantly different from human liver, whereas rat liver was significantly greater at 2.60 +/- 0.03 and 9.2 +/- 0.9 nmol of Ca(2+)/mg of protein/min, respectively. We conclude that the Ca(2+)-ATPase activity in the pig liver is equivalent to that of human liver, and thus, the pig liver is a better model than the rat liver. Cold preservation studies showed a significant decrease in porcine hepatic PM Ca(2+)-ATPase activity after 4 hours of storage and near-total inhibition after 12 hours. Porcine hepatic ER Ca(2+)-ATPase activity showed a 45% decrease in activity by 12 hours and a 69% decrease by 18 hours. We conclude that cold ischemia at clinically relevant times depresses PM Ca(2+)-ATPase more than ER Ca(2+)-ATPase activity in pig liver homogenates.

[Anatomic orthotopic heart transplantation: the surgical characteristics and the advantages of the method]. / Anatomicheskaia ortotopicheskaia transplantatsiia serdtsa: khirurgicheskie osobennosti i dostoinstva metodiki.

Standard technique of establishment of interatrial anastomoses allows to carry out orthotopic transplantation of the heart quickly and reliably. However the accumulation of collective experience evidences about a number of unavoidable shortcomings of such operation: rhythm disturbances, worsening of hemodynamics in discordant atrial contractions of recipient and donor, atrio-ventricular valve insufficiency, thromboembolism, coronary fistulas. Since 1990 in RRCS 25 operations were carried out with the use of standard technique and we also met with the risk of developing the above complications. In experiment on 30 mongrel dogs the technique of anatomical, truly orthotopic transplantation of the heart with six anastomoses was developed: left pulmonary veins with a common cuff, separate anastomoses of the superior and inferior caval veins, anastomoses of aorta and pulmonary artery. Particular attention was paid to developing of original surgical modes for prophylaxis of stenoses in the area of anastomoses of pulmonary and caval veins. In 1997 the anatomical technique of heart transplantation was successfully introduced by us into clinical practice. Clinical electrophysiological, echocardiographic and functional examinations have confirmed the results of the experiments and have evidenced for substantial advantages of the anatomical technique of orthotopic transplantation of the heart. By reliability the new operation is not inferior to standard method of N. Shumway.

[Myocardial metabolism and functional capacity in various types of cardiac reperfusion]. / Metabolizm i funktsional'naia sposobnost' miokarda pri razlichnykh vidakh reperfuzii serdtsa.

Myocardial metabolism and function were studied in 128 patients operated on under extracorporeal circulation for acquired heart diseases. Three groups of patients with different types of cardiac reperfusion were analyzed. Controlled (one- and two-stage) reperfusion was carried out with hyperosmotic unified solution 7 minutes before the beginning of blood recirculation and with perfusate after restoration of blood circulation. Reperfusion was spontaneous with perfusate alone in the control group. It was shown that the use of controlled reperfusion permit the negative action of oxygen and thermal shocks on the cold anoxed myocardium to be largely overcome. This is manifested by rather rapid reorganization of myocardial cells to the aerobic pathway, by inhibited activation of free oxygen radicals, by normalization of fluid-and-electrolyte balance, etc. Two-stage reperfusion was most effective in preventing myocardial metabolic disorders, as evidenced by more rare defibrillation to restore cardiac rhythm and less catecholamine uptake than those with one-stage and especially spontaneous reperfusion. With the latter, myocardial metabolic and functional disturbances were more severe and could be corrected only by the end of an operation.

[Myocardial protection from ischemic and reperfusion injuries in reconstructive heart surgery]. / Zashchita miokarda ot ishemicheskikh i reperfuzionnykh povrezhdenii pri rekonstruktivnykh operatsiiakh na serdtse.

Methods of myocardial protection from ischemic and reperfusion injuries in various operations on the open heart were compared. The study demonstrated the advantages of combined antegrade-retrograde delivery of cardioplegic solution during ischemia in aortocoronary shunting and correction of valvular defects. The method of myocardial protection from reperfusion injury by perfusing the heart with blood solution of a special composition before removing the clamp from the aorta (controlled reperfusion) proved to be effective, which was confirmed by clinical and biochemical data presented in this paper. Hence, our findings confirmed that the optimal protection of the myocardium can be attained by combined cold crystalloid cardioplegia together with controlled reperfusion of the myocardium.

[Universal system for cardioplegia]. / Universal'naia sistema dlia kardioplegii.

A universal system for the delivery of cardioplegia solutions has been described. The use of the system makes it possible to conduct all the kinds of cardioplegia, i. e. antegrade, retrograde, combined and shunt cardioplegia (the combination of the first and second types with the delivery of cardioplegia solutions via coronary anastomoses). The system is a distributor with six taps, each of them supplied by a cannula for the delivery of cardioplegia solution via autovenous shunts via the aortic root and coronary sinus. Besides, at the stage of lateral aorta clamping (during aortocoronary bypass surgery) the delivery of oxygenated blood from cardiopulmonary bypass apparatus to the respective myocardial segments via autovenous shunts is possible. The above system improves even distribution and cooling of various myocardial zones, especially in the area of affected coronary arteries and makes it possible to shorten the period of warm-induced ischemia of myocardial shunts.