The relaxation induced by nicotine in the rat isolated renal artery.

The mechanism of nicotine-induced relaxation was investigated in the rat isolated renal artery. Nicotine (10(-3) M) produced a relaxation when preparations were precontracted by phenylephrine (3 x 10(-6) M). Nicotine-induced relaxation was 27.3 +/- 2.5% of phenylephrine contraction and was not affected by atropine (10(-5) M), guanethidine (10(-5) M), hexamethonium (10(-4) M), indomethacin (10(-5) M), N(G)-nitro-L-arginine (10(-4) M), methylene blue (10(-5) M), glibenclamide (10(-5) M), quinacrine (3 x 10(-6) M), tetrodotoxin (10(-6) M), capsaicin (10(-6) M), tetraethylammonium (10(-3) M), 4-aminopyridine (10(-3) M), and ouabain (10(-6) M) (n = 6, Mann-Whitney U-test). A calcium antagonizing effect of nicotine was not observed. Therefore, it appears that nicotine relaxes rat isolated renal artery by a nonspecific action on the vascular smooth muscle.