Vasomotion has chloride-dependency in rat mesenteric small arteries
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- Boedtkjer, D.M.B., Matchkov, V.V., Boedtkjer, E. et al. Pflugers Arch - Eur J Physiol (2008) 457: 389. doi:10.1007/s00424-008-0532-3
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The possibility that Ca2+-activated Cl− conductances (CaCCs) contribute to oscillations in vascular tone (vasomotion) is tested in isolated mesenteric small arteries from rats where cGMP independent (ICl(Ca)) and cGMP-dependent (ICl(Ca,cGMP)) chloride conductances are important. The effect of anion substitution and Cl− channel blockers on noradrenaline (NA)-stimulated tension in isometrically mounted mesenteric arteries and for chloride conductance of smooth muscle cells isolated from these arteries were assessed electrophysiologically. Cl−o replacement with aspartate blocked vasomotion while 36mM SCN−o (substituted for Cl−) was sufficient to inhibit vasomotion. Oscillations in tone, membrane potential, and [Ca2+]i disappeared with 36mM SCN−. DIDS and Zn2+ blocked ICl(Ca,cGMP) but not ICl(Ca). Vasomotion was not sensitive to DIDS and Zn2+, and DIDS and Zn2+ induce vasomotion in arteries without endothelium. The vasomotion in the presence of DIDS and Zn2+ was sensitive to 36mM SCN−o. The anion substitution data indicate that Cl− is crucial for the Vm and [Ca2+]i oscillations underlying vasomotion. The Cl− channel blocker data are consistent with both CaCCs being important.