Vasomotion has chloride-dependency in rat mesenteric small arteries.
The possibility that Ca(2+)-activated Cl(-) conductances (CaCCs) contribute to oscillations in vascular tone (vasomotion) is tested in isolated mesenteric small arteries from rats where cGMP independent (I (Cl(Ca))) and cGMP-dependent (I (Cl(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 [Ca(2+)](i) disappeared with 36mM SCN(-). DIDS and Zn(2+) blocked I (Cl(Ca,cGMP)) but not I (Cl(Ca)). Vasomotion was not sensitive to DIDS and Zn(2+), and DIDS and Zn(2+) induce vasomotion in arteries without endothelium. The vasomotion in the presence of DIDS and Zn(2+) was sensitive to 36mM SCN(-) (o). The anion substitution data indicate that Cl(-) is crucial for the V (m) and [Ca(2+)](i) oscillations underlying vasomotion. The Cl(-) channel blocker data are consistent with both CaCCs being important.
Department of Physiology, Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Allé 1160, DK-8000, Aarhus C, Denmark. db@fi.au.dk
D M Briggs
DM
Boedtkjer
V V
VV
Matchkov
E
E
Boedtkjer
H
H
Nilsson
C
C
Aalkjaer
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D020013:Calcium Signaling; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006016:Glycolates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008297:Male; D008564:Membrane Potentials; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D009544:Niflumic Acid / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013861:Thiocyanates / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D015032:Zinc / Q000378:metabolism
D018118:Chloride Channels; D002712:Chlorides; D006016:Glycolates; D013861:Thiocyanates; D014662:Vasoconstrictor Agents; D001224:Aspartic Acid; D009544:Niflumic Acid; C015765:MK 473; D015032:Zinc; C031760:thiocyanate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D009638:Norepinephrine