| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ALIMENTARY |
1 Department of Physiology and Cell Biology, University of Nevada, School of Medicine, Reno, NV 89557, USA
Enterochromaffin (EC) cells are sensors that detect chemical or mechanical stimuli and respond with release of serotonin (5-HT). 5-HT activates local motor reflexes, but whether local motor reflexes also evoke 5-HT release is unknown. The aim of the present study was to establish the relationship between the release of 5-HT and the enteric neural circuits controlling the movements of the intestine. Recordings were made from full-thickness preparations of guinea pig ileum using electrochemical techniques with carbon fibre electrodes to measure local concentrations of 5-HT. The tension in the circular muscle (CM) and longitudinal muscle (LM) was recorded with force transducers. The release of 5-HT from the EC cells was detected selectively and the timing of the events quantified. Pressure-evoked peristalsis caused detectable 5-HT release only when the recording site was invaded by a ring of CM contraction. Spontaneous and stretch-evoked reflex contraction of the CM and LM occurred simultaneously with 5-HT release. Paralysis of the smooth muscle significantly reduced the stretch-evoked release. Muscarinic agonists evoked reflexes that were associated with increases in tension in CM and LM simultaneous with 5-HT release. Tetrodotoxin abolished the coordination between the CM contraction and 5-HT release but not the direct activation of the CM and EC cells by the agonists. In conclusion, the correlation between local motor reflexes and 5-HT release observed in the present study is caused primarily by the contraction of the smooth muscle and subsequent deformation of the mucosa. The EC cell is, thus, a site of convergence for mechanical forces that contribute to the release of 5-HT during motor reflexes.
(Received 25 July 2006;
accepted after revision 6 September 2006;
first published online 6 September 2006)
Corresponding author P. P. Bertrand: Department of Physiology and Cell Biology, University of Nevada, School of Medicine, Reno, NV 89557, USA. Email: p.bertrand{at}gmail.com
This article has been cited by other articles:
|
|
 |
|
  M. H. Larsson, M. Sapnara, E. A. Thomas, J. C. Bornstein, E. Lindstrom, D. J. Svensson, and H. Sjovall Pharmacological analysis of components of the change in transmural potential difference evoked by distension of rat proximal small intestine in vivo Am J Physiol Gastrointest Liver Physiol, January 1, 2008; 294(1): G165 - G173. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Tsukamoto, H. Ariga, C. Mantyh, T. N. Pappas, H. Yanagi, T. Yamamura, and T. Takahashi Luminally released serotonin stimulates colonic motility and accelerates colonic transit in rats Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R64 - R69. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Gwynne and J. C. Bornstein Local inhibitory reflexes excited by mucosal application of nutrient amino acids in guinea pig jejunum Am J Physiol Gastrointest Liver Physiol, June 1, 2007; 292(6): G1660 - G1670. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
