Portal de Periódicos da CAPES

Metabolic effects of inosine and uridine in rabbit hearts and rat skeletal muscles

1977; Elsevier BV; Volume: 26; Issue: 17 Linguagem: Inglês

10.1016/0006-2952(77)90073-9

1873-2968

J. Kypson, Gershon Hait,

Calcium signaling and nucleotide metabolism

Because of their cardiotonic properties and their close relations with tissue energetic stores, we studied the inotropic and metabolic effects of inosine and uridine in isolated perfused rabbit hearts and incubated rat diaphragm muscles. Inosine and uridine in concentrations of 10−5 M increased myocardial contractility, glucose uptake, myocardial glycolysis and the breakdown of ATP in rabbit hearts. Uridine also increased glycogen content, most probably due to a stimulation of glycogen synthesis by this nucleoside. Neither nucleoside had an effect on myocardial lipolysis. Similarly, inosine in concentrations of 10−4 to 10−6 M stimulated glucose uptake and the rate of glycolysis in incubated rat diaphragm muscles. On the other hand, uridine in concentrations of 10−4 to 10−6 M stimulated glucose uptake and the content of glycogen in diaphragm muscles. However, no effect of uridine on glycogen content was observed when these muscles were incubated in Krebs bicarbonate medium without glucose. The inotropic and metabolic effects of inosine, but not of uridine, were abolished in isolated rabbit hearts treated with 10−5 M propranolol. Despite this inhibition, it seems unlikely that the action of inosine and uridine is mediated by endogenous catecholamines. On the other hand, their metabolic effects are similar to those of cardiac glycosides.