Prostaglandin specific binding in hamster myometrial low speed supernatant.
A charcoal adsorption method was developed to measure specific prostaglandin binding in low speed supernates of hamster myometrial homogenates. This method was used to characterize and quantitate PGE-1-specific binding. The equilibrium binding constants and the concentration of specific PGE-1 binding sites were determined during the hamster estrous cycle. The apparent association constant for 12 different preparations was 1.16 plus or minus 0.08 times 10-9M-1. The concentration of PGE-1 specific binding sites was significantly higher on days 2 and 3 of the estrous cycle that it was on days 1 or 4. The competition for PGE-1 binding sites by PGE-2, PGF-2alpha, tpga-1 and various PGE-1 metabolites and derivatives was measured in hamster myometrial homogenates. Relative affinities of the natural prostaglandins for the PGE-1 binding sites, calculated by parallel line assay, were: PGE-2 greater than PGE-1 greater than PGA-1 greater than PGF-2alpha. For PGE-1 metabolites the relative affinities were: PGE-1 greater than 13,14-dihydro-PGE-1 greater than 13,14-dihydro-15-keto-PGE-1 greater than 15-keto-PGE-1. For the analogs and derivatives the compounds tested ranked as: 16,16-dimethyl-PGE-1 greater than PGE-1 methyl ester greater than 17-phenyl-18,19,20-trinor-PGE-1 greater than 15(S) 15-methyl-PGE-1 methyl ester. Arachidonic acid, bis-homo-gamma-linolenic acid and 7-oxa-13 prostynoic acid had relative affinities greater than 0.1 compared to PGE-1 equal 100. Indomethacin had a relative affinity of 0.4 compared to PGE-1.
D000818:Animals; D001665:Binding Sites; D002606:Charcoal / Q000494:pharmacology; D006224:Cricetinae; D004971:Estrus / Q000187:drug effects; D005260:Female; D007213:Indomethacin / Q000494:pharmacology; D008647:Mesocricetus; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D011454:Prostaglandins A / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism* / Q000494:pharmacology; D011460:Prostaglandins F / Q000378:metabolism* / Q000494:pharmacology; D013268:Stimulation, Chemical; D013997:Time Factors; D014599:Uterus / Q000378:metabolism*
D011454:Prostaglandins A; D011458:Prostaglandins E; D011460:Prostaglandins F; D002606:Charcoal; D007213:Indomethacin