Evidence for Non-Syncytial Nature of Cardiac Muscle from Impedance Measurements.

Abstract

The DC specific resistances of dog and beef ventricular muscle strips were compared with those of cat intestine circular smooth muscle, which is a non-syncytial tissue, and of frog sartorius muscle where individual cells extend almost the full length of muscle. Resistances were measured in the direction of fiber orientation before and after the interspace ion concentration was reduced by soaking in isotonic 10% Tyrode''s-sucrose solution. Cardiac and smooth muscle resistances were much more sensitive to interspace ion depletion than was skeletal muscle resistance. It is suggested that the current flow path through the cells of cardiac muscle is of high resistance due to large number of high resistance cellular membranes involved, as in smooth muscle. It was concluded that cardiac muscle cells are separated from each other by high resistance membranes and do not form a functional syncytium.