Angiotensin II-like immunoreactivity in human ovarian follicular fluid

Human ovarian follicular fluid (hFF) has angiogenic activity, although the causative factors are unknown. We recently found that hFF contains renin activity which converts renin substrate to angiotensin I (AI). Since the enzymatic cleavage product of AI, angiotensin II (AII), is a potent stimulator of new vessel formation, we have examined Sephadex G-25 column fractions of hFF and extracted hFF and plasma from individual patients for AII-like immunoreactivity (AII-IR). Eluent fractions from Sephadex G-25 column chromatography of hFF had significant AII-IR which eluted in the same fractions as synthetic AII. Individual, extracted FF samples contained approximately 10 times higher levels of AII-IR than extracts of plasma from the same patients. Serial dilutions of the Sephadex column fractions and extracted FF and plasma inhibited binding of 125I-AII to rabbit anti-AII serum in a manner parallel to the inhibition caused by synthetic AII, indicating that the detected immunoreactivity was not due to non-specific assay interference. In summary, the results indicate the presence of significant AII-like immunoreactivity in hFF. AII may now be considered as a potential mediator of the angiogenic activity present in hFF and may play an important paracrine and/or autocrine role in physiologic events in the ovary.