RELAXATION OF GUINEA-PIG STOMACH BY BRADYKININ

  • 1 January 1981
    • journal article
    • research article
    • Vol. 249  (2) , 229-234
Abstract
Intraluminal pressure changes were recorded from guinea pig stomachs in vitro. Bradykinin (Bk) (0.4-9.6 nM) produced a biphasic response (relaxation followed by contraction) in bathing solutions containing 1.1 mM CaCl2. In bathing solutions containing 5.2 mM CaCl2 a relaxation without contraction was observed. Relaxations to Bk were unaffected by selective concentrations of tetrodotoxin (5.6 .mu.M), phentolamine (5.0-50.0 mM) and propranolol (5.0-50.0 .mu.M). 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 [epinephrine] (2.0 .mu.M) by 25.9%, indicating that Bk is unlikely to be the inhibitory transmitter released during vagal stimulation. Relaxations to ATP (10 .mu.M) were reduced by 89.4% suggesting that Bk and ATP share a common step in the production of relaxation.