Prostaglandin F2 alpha stimulates phosphatidylinositol 4,5-bisphosphate hydrolysis and mobilizes intracellular Ca2+ in bovine luteal cells.

Publisher Website
Google Scholar
Abstract
The present studies were conducted to determine whether prostaglandin F2.alpha. (PGF2.alpha.) stimulates the production of "second messengers" derived from inositol phospholipid hydrolysis and increases intracellular free Ca2+ ([Ca2+]i) in isolated bovine luteal cells. PGF2.alpha. provoked rapid (10 sec) and sustained (up to 60 min) increases in the levels of inositol mono-, bis-, and trisphosphates (InsP, InsP2, and InsP3, respectively). Insp3 was formed more rapidly than InsP2 or InsP after PGF2.alpha. treatment. In addition, PGF2.alpha. increased inositol phospholipid turnover, as evidenced by increased 32PO4 incorporation into phosphatidic acid and phosphatidylinositol. LiCl (1-20 mM) enhanced inositol phosphate accumulation in response to PGF2.alpha.. Maximal increases in InsP3 occurred at 1 .mu.M PGF2.alpha., with half-maximal stimulation occurring at 36 nM. The acute effects of PGF2.alpha. on Insp3 levels were independent of reductions in extracellular calcium. Prostaglandins E1 and E2 also stimulated increases in inositol phosphate levels, albeit to a lesser extent. PGF2.alpha. also induced rapid and concentration-dependent increases in [Ca2+]i as measured by quin-2 fluorescence. The PGF2.alpha.-induced increases in [Ca2+]i were maximal within 30 sec (approximately 2- to 3-fold), and [Ca2+]i remained elevated for 8-10 min. The PGF2.alpha.-induced increases in [Ca2+]i were also independent of extracellular calcium. These findings demonstrate that the action of PGF2.alpha. is coupled to the phospholipase C-Insp3 and diacylglycerol second messenger system in the corpus luteum.