PROTECTIVE EFFECTS OF DIMETHYL-PROPRANOLOL (UM-272) DURING GLOBAL-ISCHEMIA OF ISOLATED FELINE HEARTS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 212  (3) , 560-568
Abstract
This study was designed to determine the effects of dimethylpropranolol (UM-272) on myocardial injury after global ischemia of isolated feline hearts. Untreated ischemic hearts developed contracture, resulting in a leftward shift of the diastolic pressure-volume curve. Active pressure development in perfused ischemic hearts was significantly depressed compared to preischemic values. Untreated ischemic hearts exhibited increased H2O, Na+ and Ca2+ contents and depletion of K+. The Ca2+ accumulating ability of cardiac microsomal fractions isolated from untreated ischemic hearts was severly depressed. In hearts treated with UM-272, active ventricular pressure development after ischemia declined to the same extent as in untreated hearts, but ischemic contracture in treated hearts was delayed and completely reversed by reperfusion. Treated hearts were not depleted of K+ and changes in Na+ and Ca2+ were significantly less than in untreated hearts. Microsomal Ca2+ accumulation in the treated group was well preserved compared to that in untreated hearts. Experiments in which hearts were paced during UM-272 administration suggest that decreased myocardial O2 consumption contributes substantially to the protective effects of UM-272. UM-272 may protect the ischemic heart through direct effects on myocardial Ca2+ regulating mechanisms.