The contribution of nitric oxide on the relaxation effects of diethylstillbestrol

Objective was to evaluate the contribution of nitric oxide NO on the relaxation effects diethylstilbestrol on rat uterus. Uterine rings from 8 non-pregnant Wistar Albino rats 300-350g in the pro-estrous phase were suspended in an organ bath and electrical field stimulation applied for recording isometric tension. The influences of NO on contractile responses of rat uterine rings were investigated. The effects of NO precursor L-arginine 10-7-10-4M concentration and NO synthase inhibitor-L-nitro-arginine-methyl ester 10-7-10-4M concentration and a combination of them on contractile responses were studied in the presence and absence of diethylstilbesterol 2X10-4M concentration. The study was carried out at the Department of Pharmacology Laboratory, Faculty of Medicine, Dicle University, and Diyarbakir, Turkey. Totally, 30 samples were investigated n=6 for each group, 5 groups. Diethystilbesterol inhibited contractile responses 64.2 +/- 4.5% n=6, p<0.05. Contractile responses decreased in the presence of L-arginine n=6, p<0.05 and this inhibition was abolished in the presence of L-nitro-arginine-methyl ester n=6, p<0.05. The inhibition on contractile responses to diethylstilbesterol was potentiated in the presence of L-arginine under similar conditions n=6, p<0.05. The contractile responses electrical field stimulation in the presence of diethylstilbesterol were not affected by L-nitro-arginine-methyl ester n=6, p>0.05. These data provide evidence that NO may potentiate the inhibitory effects of diethylstilbesterol by different mechanisms on the electrically induced contractions of the non-pregnant rat uterus. (author)