Effects of l‐arginine and sodium nitroprusside on the spontaneous contractility of human non‐pregnant uterus

BACKGROUND: The aim of this study was to investigate, in isolated human non‐gravid myometrium, the involvement of the cyclic guanosine monophosphate (cGMP) pathway in nitric oxide (NO) induced relaxation. METHODS: Strips of human myometrium from hysterectomized women were suspended in organ baths for recording of isometric tension. Cumulative concentration‐response curves for l‐arginine and sodium nitroprusside were performed in the presence of methylene blue (10 µmol/l) or vehicle (control). The effect of increasing concentrations of 8‐bromo‐cGMP on uterine spontaneous contraction was also studied. RESULTS: l‐arginine and sodium nitroprusside induced a concentration‐dependent decrease in the amplitude of the myometrial spontaneous contractions. Pre‐treatment with methylene blue enhanced the inhibitory effect of l‐arginine and sodium nitroprusside on myometrial spontaneous contractions. In addition, 8‐bromo‐cGMP had no effect on spontaneous contractions in human myometrium. CONCLUSIONS: These data provide evidence that l‐arginine and sodium nitroprusside inhibit the spontaneous contractions of the non‐pregnant human uterus through a cGMP independent pathway.