The contribution of nitric oxide and endothelins to angiotensin II. Evokedresponses in the rat isolated uterus smooth muscle

The present study was designed to determine the role of endogenous endothel in peptides and nitric oxide on angiotensin II (AII) responses in the isola ted nonpregnant rat uterine smooth muscle. AII (10, 20, or 50 ng/ml) increa ses rhythmic oscillations dose dependently (32.7 +/- 8.9, 55.96 +/- 10.3, a nd 62.78 +/- 17.7% increase, respectively). L-arginine methyl ester (L-NAME ; 10(-5) M) did not affect the increase in rhythmic oscillations induced by AII (10, 20, or 50 ng/ml) (17.5 +/- 12.1, 31.5 +/- 18.3, and 52.5 +/- 11.8 % increase, respectively, n = 6, p > 0.05), It reduced the contractile resp onses to AII(10 ng/ml: from 4.63 +/- 0.6 to 1.8 +/- 0.7 cm(2), p < 0.05; an d 20 ng/ml: from 5.59 +/- 0.8 to 2.11 +/- 0.4 cm(2), p < 0.05, n = 6). L-ar ginine (10 mM) decreased the contractile response obtained by AII (10 or 20 ng/ml) (1.93 +/- 1.05, p < 0.05 and 2.14 +/- 0.7 cm(2), p < 0.05, respecti vely, n = 6). BQ 485 (50 ng/ml) decreased both the number of rhythmic oscil lations and the contractility increased by AII. Bosentan (10(-5) M) induced an increase in the number of rhythmic oscillations but decreased the contr actile responses to the higher concentrations of AII. These data show that endogenous NO and endothelin peptides contribute to the motility changes in duced by AII and may play an important role in the pathophysiological event s of the uterine function. (C) 1999 Elsevier Science Inc. All rights reserv ed.