Proceedings of Annual Meeting of the Physiological Society of Japan
Proceedings of Annual Meeting of the Physiological Society of Japan
Session ID : 1S-12E-4
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Cellular functions (ciliary beating and ecocytosis) coupled with Cl transport
*Takashi Nakahari
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Abstract
In many epithelial cells, intracellular Cl concentration ([Cl]i) is maintained by Na+/K+/2Cl cotransport (NKCC, influx) and Cl channels (efflux). Inhibition of NKCC (bumetanide) decreased [Cl]i and inhibition of Cl channels increased it. Our recent studies demonstrated that bumetanide (20 μM) or a Cl-free (NO3) solution enhanced ACh-stimulated exocytosis in guinea pig antral mucous cells, in contrast, NPPB (a Cl channel blocker) decreased it and eliminated the enhancement induced by bumetanide or NO3 solution. An [Cl]i decrease modulates ATP-dependent priming in Ca2+-regulated exocytosis. And, [Ca2+]i measurements showed that bumetanide and NO3 solution enhanced the ACh-stimulated [Ca2+]i increase. Measurements of [Cl]i revealed that ACh decreases [Cl]i, and that bumetanide and NO3 solution decreased [Cl]i and enhanced the ACh-evoked [Cl]i decrease; in contrast, NPPB increased [Cl]i and inhibited the [Cl]i decrease induced by ACh, bumetanide or NO3 solution. Thus, an [Cl]i decrease accelerates ATP-dependent priming and [Ca2+]i increase, which enhance Ca2+-regulated exocytosis in ACh-stimulated antral mucous cells. Moreover, in bronchiolar ciliary cells, an [Cl]i decrease also enhanced ciliary beat frequency by modulating cAMP actions. These observations indicate that the Cl transport plays an important role in the regulation of cellular functions in epithelia. [J Physiol Sci. 2008;58 Suppl:S22]
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© 2008 The Physiological Society of Japan
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