Effects of bradykinin B2 receptor stimulation at submucosal ganglia from rat distal colon.
Bradykinin acts as an inflammatory mediator in the gut. In the present study we characterized bradykinin-induced changes in the intracellular calcium concentration ([Ca(2+)](i)) in whole-mount submucosal preparations from rat distal colon and examined the bradykinin receptors and subsequent signalling cascades involved. Bradykinin (2.10(-10)-2.10(-7)mol/l) evoked a concentration-dependent increase in [Ca(2+)](i) in about 90% of the investigated neurones. This Ca(2+) response was abolished by the bradykinin B(2) receptor antagonist HOE 140. The B(2) receptor agonist [Hyp(3)]-bradykinin mimicked the kinin response. In contrast, the B(1) receptor antagonist [des-Arg(10)]-HOE 140 and the B(1) receptor agonist bradykinin fragment 1-8 were ineffective. Immunohistochemical experiments confirmed the presence of bradykinin B(2) receptors in submucosal neurones. The effect of bradykinin on [Ca(2+)](i) was not mediated by a release of prostaglandins, as it was resistant against the cyclooxygenase inhibitor indomethacin. Blocking of G(q/11) proteins with YM-254890 suppressed the action of bradykinin, revealing that neuronal bradykinin B(2) receptors are coupled to this G protein. However, the subsequent signalling cascade differed from the classical phospholipase C signalling pathway, as the bradykinin response was resistant against the phospholipase C inhibitor U-73221, the ryanodine receptor antagonist dehydroryanodine, and only marginally sensitive against the blocker of IP(3)-receptors xestospongin C. Vice versa, the effect of bradykinin was nearly completely dependent on the presence of external Ca(2+) and could be reduced by lanthanum, a blocker of voltage-operated Ca(2+) channels, suggesting that the bradykinin-induced Ca(2+) response is achieved by an influx from the extracellular space via voltage-operated Ca(2+) channels.
Avemary
Janine
J
Institute for Veterinary Physiology, University of Giessen, Germany.
Diener
Martin
M
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005260:Female; D016257:Fura-2 / Q000378:metabolism; D005724:Ganglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D057054:Molecular Imaging; D009092:Mucous Membrane / Q000294:innervation; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043782:Receptor, Bradykinin B2 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D015220:Calcium Channels; D011453:Prostaglandins; D043782:Receptor, Bradykinin B2; D001920:Bradykinin; D002118:Calcium; D016257:Fura-2