[Effect of Adiponectin on endothelial dysfunction in obese rats].

OBJECTIVE: To test the effect of Adiponectin on endothelium-dependent and non-dependent vasodilation in food-induced obese SD rats. METHODS: Ten male Sprague-Dawley rats were divided into 2 groups: the rats in the control group (n=5) were fed with normal chow; The rats in the experimental group were fed with high fat chow (n=5). At the end of the sixth week, all rats were killed and the thoracic aortas were harvested. The vessel rings obtained from the obese rats were pre-incubated for 2 hours with adiponectin, or adiponectin plus L-NAME, or none of them, then equilibrated in Krebs-Henseleit solutions. Constriction of the vessel rings were induced by norepinephrine followed by relaxations with increasing doses of acetylcholine (for endothelium dependent vasodilatation, EDV) or sodium nitroprusside (for endothelium independent vasodilation, EIV). Vasorelaxation was expressed as percentage of residual of maximal contraction. RESULTS: Acetylcholine (10(-8)-10(-4) mol/L) caused a concentration-dependent relaxation in all preconstricted aortic rings. Compared with the control group, the maximal endothelium dependent relaxation of the aortic rings in the obese rats was impaired (p<0.05). With Adiponectin, the relaxation response of aortic rings to acetylcholine improved (P<0.05). Sodium nitroprusside (10(-8)-10(-4) mol/L) induced relaxation (endothelium independent relaxation) did not differ statistically between the two groups. CONCLUSION: Impaired endothelium-dependent vasodilatation has been observed in food-induced obese rats and Adiponectin can improve the endothelial dysfunction in obese rats.