No abstract

Using a system developed at the National Research Council of Canada the effect of ultrasound on cardiac muscle electrophysiology and on contractile properties of the myocardium has been studied. Preliminary results have been obtained from seven rat papillary muscles. Ultrasound led to a decrease in resting tension of the papillary muscles which paralleled a cellular hyperpolarization of the resting potential of 3 to 5 mV. In addition ultrasound led to an increase in the overshoot of the action potential of 26 mV. Observed changes in overshoot may be explained due to temperature changes, however changes in resting potential cannot.