Plasma concentrations of nitrate during the menstrual cycle, ovarian stimulation and ovarian hyperstimulation syndrome.
BACKGROUND
Nitric oxide (NO) is predominantly a locally acting mediator, affecting several functions in the human female reproductive tract. In vivo, it is quickly metabolized to its stable end product nitrate, which is cleared by the kidney.


RESULTS
The aim of the present study was to evaluate possible fluctuations of plasma nitrate concentrations during the menstrual cycle, ovarian stimulation as well as ovarian hyperstimulation syndrome (OHSS). During the menstrual cycle (n = 19 women) the mean nitrate concentrations were between 26.7 and 29.5 micromol/l at all stages except for the day of ovulation, when the concentrations were significantly (P < 0.001) increased (mean 37.2 micromol/l +/- 2.0). Significantly lower concentrations of plasma nitrate (P < 0.01) were measured at the end of gonadotrophin-releasing hormone (GnRH) down-regulation (24.6 micromol/l +/- 1.4) compared with the concentrations found at day 8 of follicle-stimulating hormone (FSH) stimulation (34.9 micromol/l +/- 2.6) and at the day of human chorionic gonadotrophin (HCG) (35.6 micromol/l +/- 3.3). The concentrations of nitrate (33.4 micromol/l +/- 3.4) in women with OHSS (n = 13) were similar to those seen 5 days after embryo transfer (33.2 micromol/l +/- 2.3).


CONCLUSIONS
The results indicate that NO synthesis is increased at the time of spontaneous ovulation. GnRH treatment inhibits NO synthesis, while NO production is not increased in women with OHSS.
Ekerhovd
E
E
Department of Obstetrics and Gynaecology, Göteborg University, 413 45 Göteborg, Sweden. erling.ekerhovd@obgyn.gu.se
Enskog
A
A
Caidahl
K
K
Klintland
N
N
Nilsson
L
L
Brännström
M
M
Norström
A
A
D000328:Adult; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D004624:Embryo Transfer; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D006801:Humans; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism; D008597:Menstrual Cycle; D009566:Nitrates / Q000097:blood*; D016471:Ovarian Hyperstimulation Syndrome / Q000097:blood*; D010060:Ovulation; D010062:Ovulation Induction; D011994:Recombinant Proteins / Q000008:administration & dosage; D012016:Reference Values
D006063:Chorionic Gonadotropin; D009566:Nitrates; D011994:Recombinant Proteins; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone