Nitric oxide synthesis in human nonpregnant myometrium and uterine myomas

Objective: To clarify whether nitric oxide (NO) synthesis in myomas differs from that in parental human myometrium. Design: Prospective study. Setting: Academic research institution. Patient(s): Twenty-one patients undergoing laparoscopy or laparotomy for uterine myoma. Main Outcome Measure(s): Measurement of NO synthase activity in homogenates from myoma and parental myometrium biopsies, and NO synthesis assessment in cultured smooth-muscle cells. Result(s): Nitric oxide synthase activity in homogenates did not significantly differ between myoma and healthy myometrium. The medium taken from myoma cultures showed a significant increase in nitrite concentration compared with that taken from control myometrium cultures, but 24-hour incubation of both cell types with physiologic concentrations of 17beta-estradiol or progesterone did not significantly modify nitrite production. Conclusion(s): The maximal activity of NO synthase does not differ in myoma cells and in normal myometrial cells, but basal NO synthesis seems to be enhanced by an unknown signaling pathway that is not controlled by 17beta-estradiol or progesterone. (Fertil Steril((R)) 2003;79(Suppl 4):749-53. (C) 2003 by American Society for Reproductive Medicine.).