SYMPATHOADRENAL ACTIVITY DURING EXERCISE IN PARTIAL DIABETIC AND DIABETIC RATS

Insulin-dependent diabetes mellitus is associated with altered fat and carbohydrate metabolism and disturbed sympathoadrenal functioning. Th e aim of this study was to investigate whether the short-term diabetic state alters the activity of the sympathoadrenal system and of the ad renal cortex during exercise. In addition, the possible reciprocal eff ects of a deviating sympathoadrenal functioning and an altered non-est erified fatty acid (NEFA) and glucose metabolism were investigated. Th erefore, control rats, diabetic rats, and partial diabetic rats were s ubmitted to swimming (15 minutes). Permanent heart catheters allowed f requent blood sampling without disturbing the animals. Blood glucose a nd plasma NEFA levels increased during exercise. Partial dia betic ani mals showed similar effects as controls. In contrast, the glucose and NEFA increments were significantly higher in diabetic rats than in con trol and partial diabetic rats. During exercise, the very low insulin levels were unaltered in diabetic rats, whereas they decreased in the other groups. Exercise-induced elevations of plasma epinephrine and no repinephrine were similar in all groups, but were lower for corticoste rone in the diabetic animals. Therefore, these results provide evidenc e that the exaggerated NEFA mobilization in diabetic rats is only the result of reduced inhibition of lipolysis by the relative lack of insu lin. It is concluded that the short-term diabetic state does not alter the activity of the sympathetic nervous system during exercise, but l owers the activity of the adrenal cortex.