Responses of cardiac tissue to certain stimulants and inhibitors

Abstract

Rat heart slices were incubated in variable concentrations of 1) epinephrine, 2) iodoacetic acid, 3) sodium fluoride, 4) 2,4-dinitrophenol and 5) insulin. The acid-soluble ( A) and acid-insoluble ( B) glycogen fractions, as affected by these drugs, were investigated. Degradation of A was observed with all concentrations of 1 and 4 but occurred only in the stronger solutions of 2 and 3. Glycogenolysis was noted in B in both concentrations of 4, only in the stronger dosage of 3, and a glycogenolytic trend was observed in 1. The concentrations of 5 used in these experiments had no effect on A and B of rat ventricular slices. Parameters associated with the design of an experiment influence markedly the effects these drugs have on the functional vacillations of tissue glycogen.