Human follicular nitric oxide pathway: Relationship to follicular size, oestradiol concentrations and ovarian blood flow

Nitric oxide (NO) has been suggested to be involved in ovarian physiology. Our aim was to study follicular nitrite and nitrate (NO₃/NO₂) levels in women undergoing in-vitro fertilization (IVF), and to examine their relationship to follicular size, oestradiol concentrations, and ovarian artery and intra-ovarian blood flow as measured by Doppler ultrasound. A total of 15 patients from the IVF programme of Hadassah University Hospital, Mt Scopus, Israel, participated in the study. Detailed transvaginal ultrasonographic examination was performed before ovum collection, and ovarian artery and intra-ovarian blood flow were measured. While aspirating the follicles, the content of two to four of the follicles in each ovary was collected individually, the volume of follicular fluid measured, and NO₃/NO₂ concentrations were determined. A statistically significant positive correlation was found between follicular fluid NO₃/NO₂ concentrations and follicular volume (r = 0.76), as well as between NO₃/NO₂ concentrations and oestradiol concentrations (r = 0.63). A statistically significant negative correlation was found between follicular fluid NO₃/NO₂ concentrations and ovarian flow parameters as well as between NO₃/NO₂ concentrations in follicles containing 4-5 ml and ovarian artery pulsatility index.