Altered responsiveness of small uterine arteries in women with idiopathic menorrhagia.

OBJECTIVE: This study was undertaken to study vascular reactivity of small myometrial arteries in women with idiopathic menorrhagia. STUDY DESIGN: Small myometrial arteries were isolated from 6 patients with idiopathic menorrhagia and 4 controls. The contractile responses to thromboxane mimetic ( U46619) and endothelin-1 were assessed before and after incubation with N(w)-nitro-L arginine methyl ester alone or in combination with indomethacin ( Indo). Endothelium-dependent dilation to bradykinin and basal tension were compared before and after incubation with N(w)-nitro-L arginine methyl ester alone, or with N(w)-nitro-L arginine methyl ester in combination with indomethacin. RESULTS: Constriction to endothelin-1 was enhanced in idiopathic menorrhagia arteries ( P < .05). Idiopathic menorrhagia arteries demonstrated enhanced basal tension after incubation with N(w)-nitro-L arginine methyl ester, which was further exaggerated by indomethacin. NOS inhibition had no effect on basal tension in controls, but basal tension was enhanced after inhibition of cyclooxygenase-derived products ( P < .05). Bradykinin-mediated dilation was significantly increased in idiopathic menorrhagia ( P < .05). CONCLUSION: The presence of functional alterations in small myometrial arteries could contribute to idiopathic menorrhagia.