Journal article

Publication year: 2003

Pages: 183-196

Journal: Journal of Membrane Biology

Volume number: 195

Issue number: 3

ISSN: 0022-2631

DOI Link: https://doi.org/10.1007/s00232-003-0618-y

Publisher: Springer

Abstract: 
In the epithelium of rat distal colon the acetylcholine analogue carbachol induces a transient increase of short-circuit current (Isc) via stimulation of cellular K+ conductances. Inhibition of the turnover of inositol-1,4,5-trisphosphate (IP3) by LiCl significantly reduced both the amplitude and the duration of this response. When the apical membrane was permeabilized with nystatin, LiCl nearly abolished the carbachol-induced activation of basolateral K+ conductances. In contrast, in epithelia, in which the basolateral membrane was bypassed by a basolateral depolarization, carbachol induced a biphasic increase in the K+ current across the apical membrane consisting of an early component carried by charybdotoxin- and tetraethylammonium-sensitive K+ channels followed by a sustained plateau carried by channels insensitive against these blockers. Only the latter was sensitive against LiCl or inhibition of protein kinases. In contrast, the stimulation of the early apical K+ conductance by carbachol proved to be resistant against inhibition of phospholipase C or protein kinases. However, apical dichlorobenzamil, an inhibitor of Na+/Ca2+ exchangers, or a Ca2+-free mucosal buffer solution significantly reduced the early component of the carbachol-induced apical K+ current. The presence of an apically localized Na+/Ca2+-exchanger was proven immunohistochemically. Taken together these experiments reveal divergent regulatory mechanisms for the stimulation of apical Ca2+-dependent K+ channels in this secretory epithelium, part of them being activated by an inflow of Ca2+ across the apical membrane.

Harvard Citation style: Schultheiss, G., Ribeiro, R., Schäfer, K. and Diener, M. (2003) Activation of apical K+ conductances by muscarinic receptor stimulation in rat distal colon: fast and slow components, Journal of Membrane Biology, 195(3), pp. 183-196. https://doi.org/10.1007/s00232-003-0618-y

APA Citation style: Schultheiss, G., Ribeiro, R., Schäfer, K., & Diener, M. (2003). Activation of apical K+ conductances by muscarinic receptor stimulation in rat distal colon: fast and slow components. Journal of Membrane Biology. 195(3), 183-196. https://doi.org/10.1007/s00232-003-0618-y