title: Existence of P2-purinoceptors on human and porcine granulosa cells.
abstract: This study examines the possible roles of extracellular purine nucleotides in regulating ovarian granulosa cell function. Using luteinized human (L-hGC) and porcine granulosa cells (PGC), we examined the effects of purine nucleotides on intracellular free Ca2+ concentrations ([Ca2+]i), and whether they have any effect on steroidogenesis and cell proliferation. L-hGC and PGC were responsive to ATP and ADP at concentrations ranging from 0.1-100 mumol/L in a dose-dependent manner. There was a difference between L-hGC and PGC in the rank orders of agonist potencies for stimulating [Ca2+]i; for L-hGC, UTP > ATP > ATP gamma s > ADP > AMPPNP >> AMP and adenosine; for PGC, 2-methylthio ADP (2-meS ADP) > ADP > ATP = ATP gamma s = UTP > AMPPNP >> AMP and adenosine. No apparent additivity between the responses elicited by UTP and the purine nucleotides (ATP and ADP) was shown in L-hGC. On the other hand, an apparent additive effect between the responses to ADP and UTP was shown on PGC. Furthermore, ATP was a competitive antagonist of the action of ADP on [Ca2+]i levels in PGC. ATP, ADP, and AMP as well as adenosine stimulated basal progesterone and estradiol secretion from L-hGC, however, UTP had no effect on steroidogenesis in L-hGC. On the other hand, purine nucleotides and UTP as well as adenosine inhibited progesterone and estradiol secretion on PGC. However, 2-meS ADP, the most potent agonist for P2T-purinoceptors, did not affect steroidogenesis in PGC. Purine nucleotides had no influence on cell proliferation of L-hGC and PGC. These results indicate the existence of P2U-purinoceptors on L-hGC and P2U- plus P2T-purinoceptors on PGC, and that the inhibitory effect of purine nucleotides on steroidogenesis in PGC is most likely due to A1-adenosine receptors and also P2U-purinoceptors.
authors.affiliation: Jones Institute for Reproductive Medicine, Eastern Virginia Medical School, Norfolk 23507.
authors.forename: S
authors.initials: S
authors.lastname: Kamada
authors.forename: P F
authors.initials: PF
authors.lastname: Blackmore
authors.forename: S
authors.initials: S
authors.lastname: Oehninger
authors.forename: K
authors.initials: K
authors.lastname: Gordon
authors.forename: G D
authors.initials: GD
authors.lastname: Hodgen
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D004958:Estradiol / Q000096:biosynthesis; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D007986:Luteinizing Hormone / Q000494:pharmacology; D009994:Osmolar Concentration; D011374:Progesterone / Q000378:metabolism; D011685:Purine Nucleotides / Q000494:pharmacology; D011983:Receptors, Purinergic / Q000378:metabolism*; D013552:Swine
chemical_list: D011685:Purine Nucleotides; D011983:Receptors, Purinergic; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D002118:Calcium