Effect of glibenclamide on extracellular potassium accumulation and the electrophysiological changes during myocardial ischaemia in the arterially perfused interventricular septum of rabbit

Study objective – The aim was to study the effects of glibenclamide on the rate of rise of extracellular potassium concentration ([K+]0) and the electrophysiological changes that occur during myocardial ischaemia. Design – The study was performed in isolated, arterially perfused interventricular septa from the rabbit. Six septa were treated with glibenclamide 10−6 mol·litre−1 and there were six untreated controls (vehicle only). [K+]o and electrophysiological variables were compared before and during a 30 min period of global zero flow ischaemia. Measurements and main results – Prior to ischaemia, the extracellular potassium concentrations measured using potassium sensitive valino-mycin electrodes were similar in the control and glibenclamide groups being 4.0 (SEM 0.1) and 4.0 (0.1) mmol·litre−1 respectively. [K+]0 rose during ischaemia in both groups, and at 30 min was 13.3 (0.7) mmol·litre−1 in the control group. The increase in the glibenclamide group was less marked, reaching 9.2 (0.5) mmol·litre−1 (p