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Published on: January 12, 2012
Direct coupling through gap junctions is not involved in urethral neurotransmission
Maria Sancho1, Domingo Triguero, Angeles Garcia-Pascual
1Department of Physiology, Veterinary Faculty, Complutense University, Madrid, Spain.
American Journal of Physiology. Renal Physiology
|January 21, 2011
Summary
Gap junctions do not play a role in urethral neurotransmission. Researchers found connexins in smooth muscle cells and interstitial cells of Cajal, but gap junction inhibitors did not affect nerve-mediated urethral responses.
Area of Science:
- Urology
- Neuroscience
- Cell Biology
Background:
- Interstitial cells of Cajal (ICC) are implicated in urethral neurotransmission.
- Direct coupling between ICC and smooth muscle cells (SMC) via gap junctions (GJ) has been proposed but not confirmed.
Purpose of the Study:
- To investigate the distribution of connexins (Cx43, Cx40, Cx37) in the sheep and rat urethra.
- To determine the role of GJ in urethral neurotransmission.
Main Methods:
- Conventional PCR to detect connexin expression.
- Immunohistochemistry to localize connexins in urethral tissues.
- Electrical field stimulation and GJ inhibitors (18α-glycyrrhetinic acid, Cx mimetic peptides) to assess neurotransmission.
Main Results:
- Connexins (Cx43, Cx37, Cx40) were detected in the rat and sheep urethra.
- Cx43 and Cx37 immunoreactivity was found in SMC, ICC, and urothelium; Cx40 was limited to the endothelium.
- GJ inhibitors did not alter contractile or relaxant responses to electrical field stimulation, but did reduce high K+-induced contractions.
Conclusions:
- Gap junctions are not involved in urethral neurotransmission.
- The mechanism by which ICC might modulate neurotransmission remains undetermined.
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