SUPERIOR RECOVERY OF HYPERTROPHIED RAT MYOCARDIUM AFTER CARDIOPLEGIC ARREST

Background. Although cardioplegic protection of the hypertrophied hear t remains a clinical challenge, we have previously observed enhanced r ecovery in rat hearts with pressure-overload hypertrophy induced by ao rtic banding. We investigated whether this unexpected result is found in other models of hypertrophy. Methods. Hearts with hypertrophy induc ed by aortic banding or administration of desoxycorticosterone acetate were each compared with age-matched sham-operated and nonoperated con trols. Spontaneously hypertensive rats and Wistar-Kyoto controls were also compared. We evaluated left ventricular isomyosin distribution by gel electrophoresis and recovery of isolated working rat hearts arres ted at 8 degrees C for 2 hours. Results. The percentage of V-3 isomyos in in hearts with hypertrophy from aortic banding or administration of desoxycorticosterone acetate was increased compared with the control groups. Recovery of aortic flow in all three groups of hypertrophied h earts was at least as good or better than their respective controls. T here were no significant differences in ATP or glycogen between hypert rophied and control hearts before or after arrest. Conclusions. Enhanc ed recovery of hypertrophied hearts is not specific to a single model. This level of recovery may be supported by induction of a ''fetal gen etic program,'' exemplified in the rat by the shift in isomyosin from predominantly V-1 to the more efficient V-3 isoform, which occurs in p ressure-overloaded hearts.