Effect of insulin on oxygen free radicals and oxidative phosphorylation in liver mitochondria of diabetic rats.
OBJECTIVE
To observe the effects of insulin on liver mitochondrial respiratory function, activity of H+-ATPase, and superoxide anion free radicals production in diabetic rats.


METHODS
Rats were injected iv with alloxan 40 mg/kg to induce diabetes. The liver mitochondrial respiratory function was assayed by measurement of oxygen consumption using a Clark oxygen electrode. Superoxide anion production was assayed using chemiluminescence method. Activities of H+-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 obvious effect on respiratory rate state 4 (P > 0.05). In the insulin group, synthesis activity of H+-ATPase was obviously increased (P < 0.05) and hydrolytic activity of H+-ATPase was remarkably decreased (P < 0.01), compared with the diabetes group. Insulin 1 U/kg for 9 weeks apparently decreased the production of O2.- (P < 0.01) in liver mitochondria of diabetic rats.


CONCLUSIONS
Insulin can prevent the injury from superoxide anion in liver mitochondria, and improve the function of the liver mitochondria oxidative phosphorylation.
Huang
Q
Q
Health and Anti-Epidemic Center of Shenyang City, Shenyang 110031, China. huang_q@netease.com
Shao
L
L
Jiang
H
H
Miao
Z C
ZC
Shi
Q D
QD
Liu
S S
SS
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism
D005609:Free Radicals; D007328:Insulin; D013482:Superoxide Dismutase; D000251:Adenosine Triphosphatases; D010100:Oxygen