REDUCED SURVIVAL AFTER ISOPRENALINE DOPAMINE IN D,L-PROPRANOLOL INTOXICATED RATS/

1 Respiratory and cardiovascular failure are principle toxic effects o f beta-blocker overdose. Respiratory arrest is the primary cause of de ath in beta-blocker intoxicated rats. 2 The effect of beta-adrenocepto r agonists on respiratory and cardiovascular failure in beta-blocker o verdose was investigated in a model of acute d,l-propranolol (30 mg kg (-1) h(-1)) intoxication in spontaneously breathing rats. 3 Neither th e aselective, hydrophilic beta-agonist isoprenaline (10, 25, 50 mu g k g(-1) min(-1)), nor the beta(1)-selective, lipophilic beta-agonist fle robuterol (1,3,10 mu g kg(-1) min(-1)) and the beta(2)-selective, lipo philic beta-agonist clenbuterol (10, 25, 50 mu g kg(-1) min(-1)) had a ny beneficial effect on cardiovascular and respiratory variables or su rvival time in d,l-propranolol intoxicated spontaneously breathing rat s. 4 Isoprenaline (10 mu g kg(-1) min(-1)) had no favourable effect on haemodynamic and respiratory variables in artificially ventilated d,l -propranolol intoxicated rats either. 5 Addition of dopamine to isopre naline resulted in a significant reduction of survival time, primarily caused by a decrease in mean arterial blood pressure, in artificially ventilated d,l-propranolol intoxicated rats. Addition of glucagon to isoprenaline did not affect survival time. 6 Artificial ventilation is the most important supportive measure in d,I-propranolol intoxication in the rat.