Differential effects of ischaemia and hyperkalaemia on myocardial repolarization and conduction times in the dog.

摘要: The role of increased extracellular K+ concentration ([K+]o) in the production early electrophysiological changes induced by myocardial ischaemia, was evaluated recordings monophasic action potentials and paced endocardial evoked response. Changes duration local repolarization conduction time were during infusion hypoxia. Raising [K+]o levels systemic arterial blood from 3.4 +/- 0.5 mmol l-1 to 5.9 1.5 produced a similar shortening as seen ischaemia. Prolongation occurred only when rose 8.8 1.3 l-1. slowing acute ischaemia always greater at lower than that rates equivalent post-ischaemic venous effluent. Monophasic potential amplitude upstroke velocity reduced but not markedly affected increase [K+]o. Absolute reduction more marked apex base epicardial recordings. superimposition hypoxia on hyperkalaemia resulted time. Many all abnormalities intact heart can be related raised