A constitutively active nonselective cation conductance underlies resting Ca2+ influx and secretion in bovine adrenal chromaffin cells

Cheek, T. R. and Thorn, P. (2006) A constitutively active nonselective cation conductance underlies resting Ca2+ influx and secretion in bovine adrenal chromaffin cells. Cell Calcium, 40 3: 309-318.


Author Cheek, T. R.
Thorn, P.
Title A constitutively active nonselective cation conductance underlies resting Ca2+ influx and secretion in bovine adrenal chromaffin cells
Formatted title A constitutively active nonselective cation conductance underlies resting Ca2+ influx and secretion in bovine adrenal chromaffin cells
Journal name Cell Calcium  (ERA 2012 Listed)    (ERA 2010 Rank B)   Check publisher's open access policy
Publication date 2006
Sub-type Article
DOI 10.1016/j.ceca.2006.04.002
Volume number 40
Issue number 3
ISSN 0143-4160
Start page 309
End page 318
Total pages 10
Place of publication Edinburgh
Publisher Churchill Livingstone
Language eng
Subject 270100 Biochemistry and Cell Biology
Abstract We have combined fluorimetric measurements of the intracellular free Ca2+ concentration ([Ca2+](i)) with the patch clamp technique, to investigate resting Ca2+ entry in bovine adrenal chromaffin cells. Perfusion with nominally Ca2+-free medium resulted in a rapid, reversible decrease in [Ca2+](i), indicating a resting Ca2+ permeability across the plasma membrane. Simultaneous whole-cell voltage-clamp showed a resting inward current that increased when extracellular Ca2+ (Ca-o(2+)) was lowered. This current had a reversal potential of around 0 mV and was carried by monovalent or divalent cations. In Na+-free extracellular medium there was a reduction in current amplitude upon removal of Ca-o(2+), indicating the current can carry Ca2+. The current was constitutively active and not enhanced by agents that promote Ca2+-store depletion such as thapsigargin. Extracellular La3+ abolished the resting current, reduced resting [Ca2+](i) and inhibited basal secretion. Abolishment of resting Ca2+ influx depleted the inositol 1,4,5-trisphosphate-sensitive Ca2+ store without affecting the caffeine-sensitive Ca2+ store. The results indicate the presence of a constitutively active nonselective cation conductance, permeable to both monovalent and divalent cations, that can regulate [Ca2+](i), the repletion state of the intracellular Ca2+ store and the secretory response in resting cells. (c) 2006 Elsevier Ltd. All rights reserved.
Keyword Cell Biology
chromaffin cell
nonselective cation conductance
Ca2+ entry
Ca2+ stores
secretion
indo-1
patch clamp
Operated Calcium-channels
Vascular Smooth-muscle
Ear Artery Myocytes
Catecholamine Release
Pc12 Cells
Reciprocal Regulation
Receptor Activation
Monovalent Cations
Entry
Store
Q-Index Code C1

 
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Created: Wed, 19 Sep 2007, 17:46:23 EST