Activation of splanchnic and pelvic colonic afferents by bradykinin in mice
Article first published online: 15 AUG 2005
Neurogastroenterology & Motility
Volume 17, Issue 6, pages 854–862, December 2005
How to Cite
Brierley, S. M., Jones, R. C. W., Xu, L., Gebhart, G. F. and Blackshaw, L. A. (2005), Activation of splanchnic and pelvic colonic afferents by bradykinin in mice. Neurogastroenterology & Motility, 17: 854–862. doi: 10.1111/j.1365-2982.2005.00710.x
- Issue published online: 18 NOV 2005
- Article first published online: 15 AUG 2005
- Received: 15 April 2005 Accepted for publication: 20 June 2005
- B2 receptors;
Abstract Background: Lumbar splanchnic (LSN) and sacral pelvic (PN) nerves convey different mechanosensory information from the colon to the spinal cord. Here, we determined whether these pathways differ also in their chemosensitivity to bradykinin.
Methods: Using a novel in vitro mouse colon preparation, serosal afferents were recorded from the LSN and PN and distinguished based on their mechanosensitivity to von Frey filaments (70–4000 mg) and insensitivity to colonic stretch (1–5 g) or fine mucosal stroking (10 mg). Bradykinin was applied into a ring around mechanoreceptive fields.
Results: The LSN and PN afferents had different dynamic responses to mechanical stimuli: PN afferents required lower intensity stimuli, evoked larger responses, and displayed more maintained responses than LSN afferents. Bradykinin (1 μmol L−1) excited 66% (27 of 41) of LSN afferents. Responses to probing were potentiated after bradykinin. The concentration-dependent (EC50: 0.16 μmol L−1) response was reversed by the B2-receptor antagonist HOE-140 (10 nmol L−1). Twelve bradykinin responsive afferents were mechanically insensitive. More LSN serosal afferents responded to bradykinin than PN afferents (11%, P < 0.001) , with larger responses (P < 0.05). No mechanically insensitive PN afferents were recruited by bradykinin.
Conclusions: Bradykinin potently stimulates most splanchnic serosal afferents via B2-receptors, but few pelvic afferents. Mechanically insensitive afferents recruited by bradykinin are exclusive to the LSN.