title: Changes in duodenal contractility induced by "calcium antagonists" with different modes of action.
abstract: The inhibitory action of nifedipine, verapamil, diltiazem and trifluoperazine has been examined on isolated duodenum from rats and rabbits. On rabbit duodenum Ca2+ antagonists caused a reduction of the spontaneous motility in very low concentrations (10(-12)-10(-6)M). On rat duodenum Ca2+ antagonists inhibited the contractile response to BaCl2, CaCl2 and to field stimulation, nifedipine being the most potent compound (threshold concentration down to 10(-12)M). The above results indicated that Ca2+ antagonists can markedly alter the duodenal motility, both basal and drug-stimulated. The high potency of nifedipine and the selective antagonism by Bay K 8644 against nifedipine suggest the presence of a specific receptor for the dihydropyridines (DHP receptor) in the duodenum.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002121:Calcium Channel Blockers / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D002712:Chlorides; D004386:Duodenum / Q000187:drug effects; D004558:Electric Stimulation; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D017609:Barium Compounds; D002121:Calcium Channel Blockers; D002712:Chlorides; C024986:barium chloride; D014268:Trifluoperazine; D001464:Barium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002122:Calcium Chloride