title: Amino acid, ammonia and urea concentrations in human pre-ovulatory ovarian follicular fluid.
abstract: BACKGROUND
  This study aimed to determine amino acid (AA), ammonia and urea concentrations in human ovarian follicular fluid and to compare these concentrations with those in the circulation.
  
  
  METHODS
  Samples of pre-ovulatory follicular fluid and peripheral venous blood were obtained from 14 IVF patients. High-performance liquid chromatography (HPLC) measurements of 25 AAs were the main outcome measures.
  
  
  RESULTS
  There was a significant gradient of most AAs from plasma to follicular fluid, with the exception of glutamate, which demonstrated a three-fold increase in follicular fluid concentration (70.0 +/- 3.80 microM) compared with plasma (23.18 +/- 2.20 microM; P < 0.001). The plasma-to-follicular fluid concentration difference for glutamine (81.83 +/- 9.2 microM) was greatest among all AAs. Among essential AAs, this difference was greatest for the branched-chain AAs, isoleucine, leucine and valine. Ammonia concentrations in follicular fluid and blood were 38.87 +/- 2.23 and 22.11 +/- 1.96 microM, respectively (P < 0.001). Urea concentration in follicular fluid was 3.37 +/- 0.18 mM, a value not significantly different from plasma concentration (3.36 +/- 0.22 mM; P = 0.911).
  
  
  CONCLUSIONS
  These plasma-follicular fluid differences may reflect both the utilization of AAs and the transport characteristics of the follicular cells. There is accumulation of glutamate and ammonia in pre-ovulatory follicular fluid. The data for urea are consistent with transport by passive diffusion, with no evidence of an active urea cycle in the cells of the follicle.
authors.affiliation: Department of Gynecology, Medical University of Bialystok, Bialystok, Poland. jozwik@obgyn.edu.pl
authors.forename: Marcin
authors.initials: M
authors.lastname: Józwik
authors.forename: Maciej
authors.initials: M
authors.lastname: Józwik
authors.forename: Cecilia
authors.initials: C
authors.lastname: Teng
authors.forename: Frederick C
authors.initials: FC
authors.lastname: Battaglia
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000032:analysis*; D000601:Amino Acids, Essential / Q000032:analysis; D000641:Ammonia / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005307:Fertilization in Vitro; D015571:Follicular Fluid / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D010060:Ovulation; D014508:Urea / Q000032:analysis*
chemical_list: D000596:Amino Acids; D000601:Amino Acids, Essential; D000641:Ammonia; D014508:Urea