Electrical Impedance of Cardiac Muscle

Abstract

Impedances of cat cardiac muscle and frog sartorius muscle were compared at several frequencies before and after interspace ion depletion. Strips of parallel fibers were obtained from papillary muscles and ventricular trabeculae. The impedances were measured in the direction of fiber orientation. Interspace ion concentrations were reduced by soaking the tissues in isotonic sucrose solution. The D.C. specific resistance of cardiac muscle compared to skeletal muscle was previously reported to be two times as large in Binger's and over five times as large in 0.1 Ringer "s-suerose solution. In the present study, the relative impedances of cardiac muscle at 10.000 c.p.s. compared to that at 10 c.p.s. were 75 and 48 per cent in Ringer's and sucrose solutions, respectively. The impedance of skeletal muscle was independent of frequency in Ringer's and in sucrose solutions. These results suggest the presence of transverse membranes (perhaps the intercalated discs) of high resistance and high capacitance.