Endogenous nitric oxide modulates endothelin-1 induced contraction of bovine oviduct

We recently reported that oviduct epithelial cells in culture produce endothelin (ET) and postulated that ET could play an important role in the contraction of the oviduct. In the present study using an organ chamber myograph system, we evaluated the contractile effects of ET-1 on bovine oviduct ampullary-isthmus segments. Additionally, the possibility whether the basal release/synthesis of nitric-oxide (N(O)) and/or prostacyclin modulates the contractile effect of ET-1 was investigated. ET-1 (10(-10) to 10(-7) M) contracted oviduct rings in a concentration dependent manner (P < 0.05). ET-1 (10(-7) M) induced contractions were significantly enhanced in presence of nitric oxide synthase inhibitor N-nitro-L-arginine-methyl-ester (10(-4) M), but remained unaltered in the presence of indomethacin (10(-5) M), an inhibitor for prostacyclin synthesis. In conclusion, ET-1 induced contraction of the oviduct is reduced/modulated by endogenous basal release/synthesis of N(O).