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Assessment of myocardial subcellular function after 24 hours of in vitro preservation and transplantation

1982; Elsevier BV; Volume: 83; Issue: 2 Linguagem: Inglês

10.1016/s0022-5223(19)37310-6

1097-685X

Mark Warner, Albert Guerraty, Peter A. Alivizatos, Sung C. Choi, Buddy Hudson, Richard R. Lower, Michael L. Hess,

Mechanical Circulatory Support Devices

The excitation-contraction coupling system of canine myocardium was studied after 24 hours of preservation (continuous hypothermic perfusion) and then compared to the excitation-contraction coupling system of hearts preserved after 3 hours in 4° C isotonic saline. Heterotopic transplantation was then performed to assess the effects of reperfusion after in vitro preservation. Sarcoplasmic reticulum (SR) calcium uptake and adenosine triphosphatase (ATPase) activity and myofibrillar ATPase activity were studied. Study hearts were divided into four groups and compared to normal canine controls (n = 4): Group A (n = 4), 24 hours of preservation with hypothermia and continuous nonpulsatile perfusion; Group B (n = 4), 24 hours of preservation followed by successful heterotopic transplantation for 24 hours; Group C (n = 4), 3 hours of preservation in 4° C isotonic saline; and Group D (n = 4), 3 hours of hypothermic saline preservation followed by heterotopic cardiac transplantation. SR Ca2+-stimulated, Mg2+-dependent ATPase activity was not significantly different from control values in any of the four experimental groups. SR calcium uptake from Group A was well preserved, whereas that from Group C was significantly depressed. Following transplantation both Groups B and D demonstrated depressed calcium uptake. The coupling ratio (μmoles Ca2+ transported/μmole ATP hydrolyzed) was depressed in all groups except A. Contractile protein function measured as myofibrillar pCa-ATPase curves demonstrated a depression of maximal ATPase activity in Groups C and D but not in Groups A and B. Double reciprocal plots of myofibrillar ATPase activity revealed an increase in Km for all groups, with Group B demonstrating the least depression of enzyme affinity. It is concluded that myocardial preservation in 4° C saline for only three hours results in a significant degree of ischemic / reperfusion injury to the excitation-contraction coupling system. In contrast, the intact heart can be maintained for 24 hours by continuous, nonpulsatile, hypothermic perfusion with a minimum of ischemic/reperfusion injury to the excitation-contraction coupling system.