Influence of sodium palmitate on the cellular action of potentials of the left ventricle of isolated, perfused guinea-pig heart.

Influence of sodium palmitate on the cellular action potentials of the left ventricle of isolated, perfused guinea-pig heart. Acta Physiol. Pol. 1975, 26 (1): 1-11. Transmembrane action potentials (APs) were recorded from the left ventricle and glucose uptake was estimated in the isolated guinea-pig hearts perfused with Langendorff method. After the control period the perfusion fluid was changed for the solution of altered composition containing: 1) 0.5 mM of palmitate complexed with 4% albumin and no glucose; 2) 0.1 mM or 0.5 mM of palmitate added to solution containing 11 mM of glucose; 3) substrate-free solution; 4) solution equilibrated with 5% CO-2 + 95% N-2. In all experimental groups marked shortening of AP duration was observed accompanied by the shortening of the functional refractory period and by the desynchronization of repolarization. The effect of perfusion with the substrate-free solution was similar to that evoked by substituting palmitate for glucose. In all the groups except for anoxia, fibrillation either occurred spontaneously or it was evoked by early extra stimuli. Fibrillation was reversible in all groups except for substitution 0.5 mM palmitate for glucose. Under anoxic conditions loss of excitability was observed, and shortening of AP was smaller than under palmitate. Glucose uptake was inhibited by 30% in the presence of 0.5 mM of palmitate, but not by 0.1 mM of palmitate. Thus changes in the shape of AP are not related to the glucose uptake. The possible effect of palmitate on inhibition of cellular respiration and glycolysis is discussed.