Regulation of prostaglandin production by nitric oxide in rat smooth muscle myometrial cells

Smooth muscle myometrial cells isolated by an enzymatic method from estrogenized rats were used after 7-10 days of culture. They were incubated for 24 h with two distinct competitive nitric oxide (NO) inhibitors: NG-monomethyl-L-arginine (L-NMMA: 300 microM) and L-nitro-arginine methylester (L-NAME: 600 microM, 5 mM and 10 mM). Afterwards, the supernatants were separated in order to measure nitrite production and prostaglandin PGE synthesis. In the present report, we demonstrate that myometrial cells from estrogenized rats are able to produce NO, since all the inhibitors significantly decrease the production of nitrites in the culture media. Furthermore, we report that both inhibitors inhibited PGE synthesis by myometrial cells. We also used a donor of NO in the incubation medium for 24 h, sodium nitroprusside (NP), obtaining an strong (P< 0.001) increase in both nitrite and PGE production. We conclude that myometrial cells can produce NO and that one possible role of the NO synthetized by this cells may be the modulation of PGE production.