Responses of cardiac tissue to certain stimulants and inhibitors

¹ Department of Physiology and Pharmacology, University of Missouri Medical Center, Columbia, Missouri

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.