Effect of insulin on oxygen free radicals and oxidative phosphorylation inliver mitochondria of diabetic rats

AIM: To observe the effects of insulin on liver mitochondrial respiratory f unction, activity of H+-ATPase, and superoxide anion free radicals producti on in diabetic rats. METHODS: Rats were injected iv with alloxan 40 mg/kg t o induce diabetes. The liver mitochondrial respiratory function was assayed by measurement of oxygen consumption using a Clark oxygen electrode. Super oxide anion production was assayed using chemiluminescence method. Activiti es of HC-ATPase were measured by luciferin-luciferase system and inorganic phosphorus's method. RESULTS: Insulin 1 U/kg sc daily for 9 weeks improved oxidative phosphorylation, respiratory rate state 3 (P < 0.05), respiratory control ration (P < 0.01), and ADP:O ratio (P < 0.01), but there were no o bvious effect on respiratory rate state 4 (P > 0.05). In the insulin group, synthesis activity of H+-ATPase was obviously increased (P < 0.05) acid hy drolytic activity of H+-ATPase was remarkably decreased (P < 0. 01), compar ed with the diabetes group. Insulin 1 U/kg for 9 weeks apparently decreased the production of O-2(.-)(P < 0. 01) in liver mitochondria of diabetic rat s. CONCLUSION: Insulin can prevent the injury from superoxide anion in live r mitochondria, and improve the function of the liver mitochondria oxidativ e phosphorylation.