Determination of intracellular potassium ion concentration in isolated rat ventricular myocytes

The sarcoplasmic potassium concentration of a suspension of rat ventricular myocytes, prepared by collagenase-induced disruption of the myocardial mass, was determined by a null-point technique. Addition of digitonin resulted in a release of potassium from the cells which was interpreted as a flux from the sarcoplasm. The intracellular potassium concentration was estimated to be 113 +/- 6mM.