Role of nitric oxide in aortic contractile function of renal hypertensive rats

AIM:To investigate the changes of aortic contractile function in renal hypertension with two-kidney, one-clip (2K1C) rats and its interrelation with nitric oxide (NO). METHODS:Animals were divided into 5 groups, sham operation group, 2K1C group, captopril group, L-arginine group and L-NAME group. At 4th week after operation, isometric tension changes of aortic rings were recorded, aortric cGMP content were also measured. RESULTS:Phenylephrine, acetylcholine, angiotensin Ⅱ and high potassium chloride solution-induced contraction was significantly increased, and aortric cGMP content was lowered in aortic rings from 2K1C rats compared with rings from sham rats. These changes were abolished in 2K1C rats treated with captopril. L-arginine partially reversed the change of aortic contractibility of 2K1C rats, and elevated aortic cGMP content. In 2K1C rats treated with nitric oxide synthase inhibitor L-NAME, aortric cGMP content were decreased further, but phenylephrine-induced contractile response were unaffected. After blockade of NO production with L-NAME, the maximal responses of aortric rings relaxation to sodium nitroprussidum were not significantly different in all five groups. CONCLUSION:These results indicate that the deficiency of nitric oxide production and the increase in the contractive factor in vascular tissue may contribute to changes in aortic contractile function of 2K1C rats.