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- Title
Activation of Ca<sup>2+</sup>-activated Cl<sup>-</sup> channels by store-operated Ca<sup>2+</sup> entry in arterial smooth muscle cells does not require reverse-mode Na<sup>+</sup>/Ca<sup>2+</sup> exchange.
- Authors
Angermann, Jeff E.; Forrest, Abigail S.; Greenwood, Iain A.; Leblanc, Normand
- Abstract
The main purpose of this study was to characterize the stimulation of Ca2+-activated Cl-(ClCa) by store-operated Ca2+ entry (SOCE) channels in rabbit pulmonary arterial smooth muscle cells (PASMCs) and determine if this process requires reverse-mode Na+/Ca2+ exchange (NCX). In whole-cell voltage clamped PASMCs incubated with 1 mol/L nifedipine (Nif) to inhibit Ca2+ channels, 30 μmol/L cyclopiazonic acid (CPA), a SERCA pump inhibitor, activated a nonselective cation conductance permeable to Na+ (ISOC) during an initial 1-3 s step, ranging from-120 to +60 mV, and Ca2+-activated Cl-current (ICl(Ca)) during a second step to +90 mV that increased with the level of the preceding hyperpolarizing step. Niflumic acid (100 μmol/L), a ClCa channel blocker, abolished ICl(Ca) but had no effect on ISOC, whereas the ISOC blocker SKF-96365 (50 μmol/L) suppressed both currents. Dual patch clamp and Fluo-4 fluorescence measurements revealed the appearance of CPA-induced Ca2+ transients of increasing magnitude with increasing hyperpolarizing steps, which correlated with ICl(Ca) amplitude. The absence of Ca2+ transients at positive potentials following a hyperpolarizing step combined with the observation that SOCE-stimulated ICl(Ca) was unaffected by the NCX blocker KB-R7943 (1 μmol/L) suggest that the SOCE/ ClCa interaction does not require reverse-mode NCX in our conditions.
- Subjects
CALCIUM channels; ION channels; DIHYDROPYRIDINE receptors; LABORATORY rabbits; HEALTH outcome assessment; MUSCLE cells
- Publication
Canadian Journal of Physiology & Pharmacology, 2012, Vol 90, Issue 7, p903
- ISSN
0008-4212
- Publication type
Article
- DOI
10.1139/Y2012-081