title: Relaxation of guinea-pig stomach by bradykinin.
abstract: Intraluminal pressure changes were recorded from guinea-pig stomachs in vitro. Bradykinin (Bk) (0.4-9.6 nM) was generally found to produce a biphasic response (relaxation followed by contraction) in bathing solutions containing 1.1 mM calcium chloride. In bathing solutions containing 5.2 mM calcium chloride a relaxation without contraction was the most common observation. Relaxations to Bk were unaffected by selective concentrations of tetrodotoxin (5.6 microM), phentolamine (5.0-50.0 microM) and propranolol (5.0-50.0 microM). During virtually complete desensitization to Bk produced by 3 cumulative doses of 6.4 nM, relaxations to vagal stimulation were only reduced by 24.2% and those to adrenaline (2.0 microM) by 25.9%, indicating that Bk is unlikely to be the inhibitory transmitter released during vagal stimulation. Relaxations to ATP (10 microM) were reduced by 89.4% suggesting that Bk and ATP share a common step in the production of relaxation.
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D004347:Drug Interactions; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D013270:Stomach / Q000187:drug effects*; D014630:Vagus Nerve / Q000502:physiology
chemical_list: D001920:Bradykinin