Calcium and cardioplegia in neonates: dose-response and time-response studies in rats.
Isolated Langendorff-perfused rat hearts (n = 6/group) were subjected to 60, 90, 120, or 180 min of ischemia with or without a 2-min preischemic infusion with St. Thomas' Hospital cardioplegic solution that had been modified to contain concentrations of calcium of 0, 0.5, 0.8, 1.0, 1.2, 1.8, or 2.4 mM. In general, irrespective of the calcium concentration, hearts in the cardioplegia group recovered better than those in the noncardioplegia group. There was no consistent relationship between calcium content and postischemic recovery of function or enzyme leakage after any of the durations of ischemia studied. However, as expected, there was a strong inverse relationship between recovery and duration of ischemia. The recovery of function correlated with enzyme leakage but not with the time to onset or magnitude of ischemic contracture. In conclusion, although the neonatal rat heart benefits from cardioplegia the protection is less impressive than that reported for adult hearts. Nonetheless, the neonatal heart appears to be very resistant to ischemia. We propose that many of these differences can be explained on the basis of differences in myocardial calcium handling between neonate and adult.
Riva
E
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Cardiovascular Research, Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
Hearse
D J
DJ
D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology; D002314:Cardioplegic Solutions; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000503:physiopathology*; D006321:Heart / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D006324:Heart Arrest, Induced; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D002314:Cardioplegic Solutions; D002118:Calcium