Abstract: OBJECTIVE: To observe the protective effects on endothelium- dependent relaxation (EDR) damage induced by nicotine in the isolated rat mesenteric arteries. METHODS: An organ culture system and artery ring tension recording method were used. The mesenteric artery rings (1mm) of adult Sprague-Dawley rats were cultured with different concentration of valsartan (0.1, 1, 10μmol?L-1) for 24 hours in presence or absence of nitric oxide synthase inhibitor Nω-nitro-L-arginine(L-NAME) and prostacyclin synthase inhibitor indomethacin. The cultured-artery rings were precontracted with noradrenalin (NE, 1μmol?L-1) and subsequently relaxed by a commulative addition of ACh (10-9-10-6mol?L-1). RESULTS:　Valsartan attenuated the inhibition induced by nicotine in concentration-dependent manner. There was no significant difference between valsartan (0.1μmol?L-1) group and nicotine group (P>0.05). But the EDR of the middle, high concentration (1, 10μmol?L-1) groups were significantly potentiated compared to the arteries cultured only with nicotine (P<0.01). Furthermore, the protetive effect of valsartan was blocked by L-NAME and indomethacin. CONCLUSION:　Valsartan prevents the vascular endothelium-dependent relaxation against elcited-nicotine injury with a mechanism related to the activation of nitric oxide and prostacyclin.

Key words: nicotine, valsartan, mesenteric artery