An unexpected potent positive chronotropic effect of (15S)-15-methyl-prostaglandin E1 in the isolated guinea-pig right atria.
The effects of (15S)-15-methyl-prostaglandin E1, a synthetic analog of PGE1, other stable prostaglandins, histamine and noradrenaline were studied on the isolated spontaneously beating right atria from guinea-pig, rat and rabbit. When compared with other prostaglandins, histamine and noradrenaline, 15-methyl analog of PGE1 has the most potent positive chronotropic effect and the highest affinity as indicated by a significantly higher pD2 value as compared to other tested analogs in the isolated guinea-pig right atria. Neither the 15-methyl analog of PGE1 nor other stable prostaglandins induced any effect on the atria from rat and rabbit when relatively higher concentrations were used. 15-Methyl-PGE1 did not induce a positive inotropic effect. The maximum positive chronotropic response to 15-methyl-PGE1 was found to be about 60% of that of noradrenaline and histamine but almost equal to that of PGE1. These results were taken as evidence that 15-methyl-PGE1 has an unexpected potent positive chronotropic effect on the isolated spontaneously beating guinea-pig right atrium. The possible mechanism of the action of 15-methyl-PGE1 are discussed.
D000527:Alprostadil / Q000031:analogs & derivatives; D000818:Animals; D015237:Dinoprost; D015232:Dinoprostone; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D011459:Prostaglandins E, Synthetic / Q000494:pharmacology*; D011460:Prostaglandins F / Q000494:pharmacology; D011817:Rabbits; D051381:Rats
D011458:Prostaglandins E; D011459:Prostaglandins E, Synthetic; D011460:Prostaglandins F; C025170:15(S)-15-methylprostaglandin E1; D006632:Histamine; D015237:Dinoprost; D000527:Alprostadil; D015232:Dinoprostone; D009638:Norepinephrine