THE EFFECTS OF INSULIN AND POTASSIUM ON INFARCTING CANINE TISSUE - AN INVITRO STUDY

[摘要] The electrophysiologic effects of insulin (40 mU/ml) and elevated K (4-6 mM) on glucose-superfused normal and infarcting tissue from 24 h coronary artery ligated canine myocardium were studied. With standard intracellular microelectrode techniques, it was observed that insulin fusion for 30 min produced an increase in resting membrane potential and a prolongation of action potential duration. In the normal myocardium, the hyperpolarization and the repolarizatin delay were minimal, but in infarcting tissue with depressed electrophysiologic function, resting membrane potential and action potential duration were significantly improved. This was particularly evident in the presence of an increased K concentration (6 mM) when insulin hyperpolarized infarcting cells (n = 8) from 73 .+-. 6 to 85 .+-. 7 mV (P < 0.01). In the same studies, action potential amplitudes were increased from 75 .+-. 7 to 95 .+-. 11 mV (P < 0.01). In addition, action potential durations at 40 and 80% repolarization were extended from 64 .+-. 25 and 141 .+-. 46 ms to 132 .+-. 34 and 198 .+-. 27 ms, respectively (P < 0.01). These data are in accord with the reduced ST segment elevation observed in patients treated with glucose-insulin-K and support the use of this intervention in the management of acute infarction.