Some pharmacological effects of p-chlorophenylalanine unrelated to tryptophan hydroxylase inhibition.
1 Experiments were performed on a variety of tissues from different species to establish whether or not the properties of p-chlorophenylalanine methyl ester (PCPA) included a 5-hydroxytryptamine (5-HT)-like action which might explain the soporific action of PCPA in chicks. 2 PCPA, like 5-HT, contracted the rat fundal preparation (as did PCPA base), and in cats enhanced twitch tension of a lower limb flexor reflex, evoked adrenal medullary secretion and attenuated histamine-induced gastric secretion; the effects on the rat fundal strip and the adrenal medulla were prevented by methysergide. 3 Like 5-HT, PCPA elicited bronchoconstriction of guinea-pig lungs, isolated or in vivo; this was not prevented by methysergide but reduced by polyphloretin and by indomethacin. Perfusate collected from the lungs during PCPA-induced bronchoconstriction and applied to superfused isolated tissues contained a substance with prostaglandin-like activity. 4 In contrast, the effect of PCPA on the guinea-pig isolated ileum differed from that of 5-HT, since it relaxed the ileum when contracted by transmural excitation, by acetylcholine, histamine of 5-HT and contracted the ileum on wash-out.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism; D002415:Cats; D005260:Female; D010134:Fenclonine / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors*; D051381:Rats; D012018:Reflex / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D013045:Species Specificity; D013270:Stomach / Q000187:drug effects; D014365:Tryptophan Hydroxylase / Q000037:antagonists & inhibitors*; D014599:Uterus / Q000187:drug effects
D002395:Catecholamines; D012701:Serotonin; D006899:Mixed Function Oxygenases; D014365:Tryptophan Hydroxylase; D010134:Fenclonine