Release and specific binding of prostaglandins in bovine pineal gland.
Incubated bovine pineal glands released prostaglandin E-and prostglandin F-like material (304 +/- 20 and 582 +/- 56 pg/mg dry tissue wt/h, respectively) and the release was increased 2.2 2.9-fold by adding 10(-4)-10(-6)M of norepinephrine to the medium. Binding assays revealed the existence of high affinity binding of 3H-prostaglandin E2 (3H-PGE2) and 3H-prostaglandin F1 alpha (3H-PGF2 alpha) in low speed supernatants of pineal homogenates. Binding was increased by increasing Ca++ concentration in medium up to 2 mM, was heat labile and was depressed following incubation with trypsin. In subcellular fractionation studies maximal 3H-PG binding was found in the 27000 x g pellet. Scatchard analysis of 3H-PGE2 binding revealed the presence of a single population of binding sites with a Kd= 1.2 nM and a binding site concentration of 1-2 pmoles/g protein. A single population of binding sites for 3H-PGF2 alpha was also detected with a Kd= 1.7 nM and a similar binding site concentration. Non-radioactive PGE1 and PGE2 were almost equally effective to compete for 3H-PGE1 binding sites (ED50= 5 and 2 nM, respectively). Unlabeled PGF1 was relatively ineffective to compete for 3H-PGE2 binding (ED50 greater than 1000 nM) but displaced effectively 3H-PGF2 alpha binding (ED20=1.2 nM).
D000818:Animals; D002417:Cattle; D003470:Culture Media; D009638:Norepinephrine / Q000494:pharmacology; D010870:Pineal Gland / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism*; D011460:Prostaglandins F / Q000378:metabolism*; D011982:Receptors, Prostaglandin; D012636:Secretory Rate / Q000187:drug effects
D003470:Culture Media; D011458:Prostaglandins E; D011460:Prostaglandins F; D011982:Receptors, Prostaglandin; D009638:Norepinephrine