The anion movements across the cell membrane were regarded as a part of passive distribution according to the cation movements. Recently, from the development of patch clamp technique new concept for anion channels were introduced. And their
roles
in
the genesis of action potential and resting potential were noticed. So we clarified the existence of the chloride channel in the smooth muscle cells and studied its nature in regard to the roles of the second messangers. We used the whole cell
voltage
clamp technique to study the current responses induced by carbachol application in the circular smooth muscle cells of the gastric antrum of the rabbit.
@ES The results were as follows:
@EN 1. Application of the carbachol induced the increase of inward currents in the hyperpolarized potential ranges, and the increase of outward currents in the depolarized ranges.
2. Even in the cases of blocking all the known currents, these current components were observed.
3. Sodium ion removel from the external medium rarely affected these current responses, and the addition of cadmium ion did not make any remarkable change.
4. Known second meassangers such as c-AMP, c-GMP, heparin, ALF4-rarely affected these current components.
5. Lowering of intrcellular calcium ion concentration drastically reduced these current responses.
Form the above results we can suggest that the carbachol induced current responses contained chloride currents which were activated by only intracellular calcium ion, not by any other second messegers in the gastric antral smooth muscles cells.
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