BK₁ and BK₂ bradykinin receptors in the rat duodenum smooth muscle

Abstract

1 The dual action of bradykinin (relaxation and contraction) on the rat duodenum was investigated by studying its effect on adenosine 3':5'-cyclic monophosphate (cyclic AMP)

Pharmacological Activities and Hydrolysis by Peptidases of [Phospho-Ser6]-Bradykinin (pS6-BK)

“…The contraction response of rat uterus and guineapig ileum, and relaxation of rat duodenum, to both peptides were quantified. Rat duodenum presented dual response to [pS 6 ]Bk, relaxation at concentrations lower than 1 mM and contractions at higher concentrations, that was a similar behavior as previously reported with Bk in concentration range 30 times lower [28,29]. [pS 6 ]Bk was a full agonist but with 3% of Bk activity in all three isolated organ preparations, which was completely inhibited by HOE-140, an antagonist of bradykinin B2-receptor (Fig.…”

Receptors and mechanisms mediating the biphasic response evoked by bradykinin in rat colonic smooth muscle

“…The kinin-induced relaxation was inhibited by tetrapentylammonium chloride, a blocker of Ca 2+ -activated K + channels. Des-arg 9 -bradykinin did not induce any effect on the native colon, although after 5 h in vitro preincubation, a contractile response was evoked by this B 1 receptor agonist. The consecutive ablation of adherent layers of the intestinal wall strongly reduced the response to bradykinin in comparison with a control stimulus, i.e., carbachol, suggesting a contribution of non-muscle cells in the mediation of this response.…”

“…First row: native colonic wall; second row: colonic wall preincubated for 5 h. The arrow depicts the time point when the respective substance was added to the buffer solution. Whereas bradykinin and hyp 3 -bradykinin induced a relaxation in the native colon tissue, des-arg 9 -bradykinin was ineffective. After 5 h in vitro preincubation, the effect of bradykinin and hyp 3 -bradykinin was diminished and des-arg 9 -bradykinin induced a contraction.…”

“…2 found that the B 1 agonist des-arg 9 -bradykinin caused a contraction in rat duodenum, whereas a bradykinin analog with a higher affinity to the B 2 receptor (a specific B 2 agonist was not developed yet) showed a stronger relaxative response than native bradykinin. However, in rat colonic smooth muscle the B 2 agonist hyp 3 -bradykinin caused a biphasic change in muscle tone similar as did bradykinin (Fig.…”

Molecular biology of the kallikrein-kinin system: from structure to function

“…BK, kallidin and the other intact kinins can exert their biological function by binding with high affinity to the B2 receptors whereas the products of the action of the arginine carboxypeptidase (kininase I-activity) on kinins, the C-terminal-arginine truncated kinins, are preferential agonists for the B1 receptor (3)(4)(5). The B1 receptor is believed to mediate several of the inflammatory responses to kinins (1) and, under pathological conditions, contractile effects on visceral smooth muscle (6). The B2 receptors are constitutively expressed and widely distributed throughout mammalian tissues.…”