Improved rat heart function after low Ca2+ perfused preservation at 5 degrees C for 18 hours.
To evaluate the effect of Ca2+ on recovery of heart function after hypothermic preservation, isolated working rat hearts were perfused continuously in different [Ca2+] (0.35-2.0 mM) at 37 degrees C for 30 min, during cooling to 5 degrees C, and then at 5 degrees C for 1, 6 or 18 h. After rewarming to 37 degrees C, contractile functions were assessed in working hearts perfused with Krebs-Henseleit (K-H) solution containing 2.0 mM free Ca2+. In normal K-H solution (2.0 mM Ca2+), cardiac function recovered completely after perfusion at 5 degrees C for 1 h (measured by the maximal rate of pressure development, +dP/dtmax, and heart rate x left ventricular systolic pressure, HR x LVSP). After 6 h at 5 degrees C, significant (P < 0.05) loss in function began to appear. Further, 18 h at 5 degrees C resulted in significant decreases in LVSP, +dP/dtmax, and coronary flow (CF) and a significant increase in left ventricular diastolic pressure. The deterioration of heart function consequent to hypothermic preservation could be prevented by reducing the Ca2+ in perfusion medium prior to and during cooling and rewarming from hypothermia. The optimal Ca2+ concentration was 0.5 mM. At lower Ca2+ (0.35 mM), reductions in HR, LVSP. +dP/dtmax, and CF after rewarming were evident. Our results indicate that by reducing cellular Ca2+ prior to cooling through perfusion of 0.5 mM Ca2+ K-H solution, significant benefits can be obtained both in prolonging the duration of cardiac preservation and in retaining functional integrity upon rewarming.
Liu
B
B
Department of Zoology, University of Alberta, Edmonton, Canada.
Lopaschuk
G D
GD
Wang
L C
LC
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003326:Coronary Circulation; D015925:Cryopreservation / Q000379:methods*; D005069:Evaluation Studies as Topic; D006321:Heart / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D009926:Organ Preservation / Q000379:methods*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature; D013997:Time Factors
D002118:Calcium