Gastrointestinal Smooth Muscle Essay

It has been established for more than 40 years that Cl- is not passively distributed in gastrointestinal smooth muscle (Aickin et al 1983, Barajas Lopez et al 1989, Casteels 1971, El-Sharkawy and Daniel 1975 p1278,) and that there is a complex relationship between the distribution and transport of Cl- and the distribution and transport of other ions including Na+, K+ and Ca2+, as well as responses to changes in pH and osmolarity. The full complement of Cl- ion transporters and Cl- selective channels has not been determined for the cell types in gastrointestinal muscularis externa of any species but recently interest in understanding how Cl- homeostasis contributes to gastrointestinal smooth muscle function has revived due to the recognition that two key mechanisms for Cl- movement, the Ca2+ activated Cl- channel, Ano1 and the Na+,K+, two …show more content…
There are few reports of Cl- channels in gastrointestinal smooth muscle cells and one report that directly states that Cl- currents could not be detected in smooth muscle cells from mouse small intestine (Tokutomi et al 1995). In the light of an increased understanding of the activities and distribution of Cl- channels and transporters in gastrointestinal smooth muscle, we tested the effects of two anionic substitutes for Cl-, gluconate and isethionate, on the electrical activity of mouse small intestine. These ions are not transported by Cl- ion exchangers (Owen and Prastein 1985, Koncz and Daugirdas 1994) and permeate poorly through Cl- channels (Pezier et al 2010, Reyes 2010, Greenwood and Large 1999). The objective of these studies was to establish the relative contributions of Cl- selective ion channels and transporters in smooth muscle and ICC to the overall electrical activity in circular muscle from mouse small