Influence of hypothermia on the cardiac effects of propranolol observed in isolated rat atria.
1. The purpose was to determine if hypothermia influences cardiac responses to propranolol. 2. Rat atria were used and 11 test groups were created; 3 control groups were maintained at 35, 28 or 20 degrees C. Two additional groups, at each temperature, were exposed to 1.2 or 40 mumol/l propranolol. Developed force and effective refractory period (ERP) 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 microM propranolol neither affected developed force or ERP, but 40 microM reduced developed force and lengthened ERP.


CONCLUSIONS
hypothermia reduced propranolol's usual negative inotropic effect.
Melnikov
A L
AL
Basic Cardiac Research Laboratory, Kirkenes Hospital, Norway.
Løkebø
J E
JE
Helgesen
K G
KG
Lathrop
D A
DA
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D016275:Atrial Function; D005260:Female; D006325:Heart Atria / Q000187:drug effects*; D007036:Hypothermia, Induced; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012032:Refractory Period, Electrophysiological / Q000187:drug effects / Q000502:physiology
D000319:Adrenergic beta-Antagonists; D011433:Propranolol