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.