Circulating levels of nitric oxide in fertile women in relation to the menstrual cycle.

ABSTRACT

OBJECTIVE: To investigate nitric oxide (NO) production in the two phases of normal menstrual cycle. DESIGN: Prospective clinical study. SETTING: Normal human volunteers in an academic research environment. PATIENT(S) Fifteen normally cycling women. INTERVENTION(S) Follicle growth monitoring by ultrasound, serum, and plasma sampling in the midfollicular phase, at ovulation, and in the midsecretory phase. MAIN OUTCOME MEASURE(S) Plasma concentration of NO stable oxidation products and serum concentrations of E2 and P. RESULT(S) Plasma concentration of NO metabolites resulted higher in the follicular phase with respect to the secretory phase and peaked at midcycle. CONCLUSION(S) The results strongly support the existence of an E2 control of NO production and release. The significant reduction in NO metabolites observed in the secretory phase suggests a possible opposing action of P on either NO production or release.