Potassium and Its Effect on Glycogen in the Dog Heart

Abstract

Potassium chloride, infused into 10 anesthetized dogs until severe electrical changes were observed in the heart (electrocardiogram) and serum potassium was elevated (9.5 mEq./L.), had no apparent effect on the glycogen content of any of the 4 heart chambers. Dog ventricular slices did not tolerate a medium high in potassium. Glycogenolysis was noted when the slices were incubated in a Krebs-Ringer buffered phosphate glucose medium containing 9 mM of potassium. The glycogen loss was confined to the acid-soluble form of the polysaccharide. A homogenate of dog myocardium, incubated in a simulated "intracellular" medium for up to 50 minutes, rapidly and continuously lost acid-soluble glycogen. The acid-insoluble fraction was not degraded until the homogenate was incubated for 50 minutes.