INFLUENCE OF HYPOTHERMIA ON THE CARDIAC EFFECTS OF PROPRANOLOL OBSERVED IN ISOLATED RAT ATRIA

1. The purpose was to determine if hypothermia influences cardiac resp onses to propranolol. 2. Rat atria were used and 11 test groups were c reated; 3 control groups were maintained at 35, 28 or 20 degrees C. Tw o additional groups, at each temperature, were exposed to 1.2 or 40 mu mol/l propranolol. Developed force and effective refractory period (E RP) were measured. 3. At 35 degrees C, propranolol decreased developed force and lengthened ERP, At 28 degrees C, propranolol did not affect developed force, but ERP was lengthened. At 20 degrees C, 1.2 mu M pr opranolol neither affected de veloped force or ERP, but 40 mu M reduce d developed force and lengthened ERP. Conclusion: hypothermia reduced propranolol's usual negative inotropic effect. Copyright (C) 1997 Else vier Science Inc.