Activation of Ca2+-activated K+ (maxi-K+) channel by angiotensin II in myocytes of the guinea pig ileum

Activation of Ca2+-activated K+ (maxi-K+) channel by angiotensin II in myocytes of the guinea pig ileum

Author Romero, Fernando Autor UNIFESP Google Scholar
Silva, Bagnolia Araujo da Autor UNIFESP Google Scholar
Nouailhetas, Viviane Louise Andree Autor UNIFESP Google Scholar
Aboulafia, Jeannine Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract We investigated the regulation of the Ca2+-activated K+ (maxi-K+) channel by angiotensin II (ANG II) and its synthetic analog, [Lys(2)]ANG II, in freshly dispersed intestinal myocytes. We identified a maxi-K+ channel population in the inside-out patch configuration on the basis of its conductance (257 +/- 4 pS in symmetrical 150 mM KCl solution), voltage and Ca2+ dependence of channel opening, low Na+-to-K+ and Cl--to-K+ permeability ratios, and blockade by external Cs+( )and tetraethylammonium chloride. ANG II and [Lys(2)]ANG II caused an indirect, reversible, Ca2+- and dose-dependent activation of maxi-K+ channels in cell-attached experiments when cells were bathed in high-K+ solution. This effect was reversibly blocked by DUP-753, being that it is mediated by the AT(1) receptor. Evidences that activation of the maxi-K+ channel by ANG II requires a rise in intracellular Ca2+ concentration ([Ca2+](i)) as an intermediate step were the shift of the open probability of the channel-membrane potential relationship to less positive membrane potentials and the sustained increase in [Ca2+](i) in fura 2-loaded myocytes. The preservation of the pharmacomechanical coupling of ANG II in these cells provides a good model for the study of transmembrane signaling responses to ANG II and analogs in this tissue.
Keywords longitudinal layer
patch clamp
intracellular calcium concentration
fura 2
Language English
Date 1998-04-01
Published in American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 274, n. 4, p. C983-C991, 1998.
ISSN 0363-6143 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent C983-C991
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000072850000017

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