Autoregulation of myocardial glycogen concentration during intermittent hypoxia

摘要: During hypoxia, the heart consumes glycogen to generate ATP. Tolerance of repetitive hypoxia logically requires prompt replenishment glycogen, a process whose regulation is not fully understood. To examine this, we imposed defined hypoxic stimulus on rat while varying its workload. In intact rats, reduced myocardial approximately 30% and increased both fraction synthase in physiologically active (GS I) form (from 0.24 +/- 0.06 0.82 0.07; P < 0.005) synthesis 0.087 0.011 0.375 0.046 mumol.g-1.min-1; 0.005). Reducing cardiac work (with propranolol or heterotopic transplantation) breakdown, activation, parallel, stepwise fashion rats. Correspondingly, GS I activity perfused vitro, but only under conditions where was consumed. This suggests activated by systemic catalyzes rapid posthypoxic synthesis. Hypoxic activation appears be proportionate, wholly intrinsic response local glycogenolysis, operating preserve stores independent any extracardiac mediator carbohydrate metabolism.