Measurement of chloride flux associated with the myogenic response in rat cerebral arteries.
1. Self-referencing ion-selective (SERIS) electrodes were used to measure the temperature and pressure dependence of Cl(-) efflux, during myogenic contraction of pressurized rat cerebral resistance arteries. 2. At room temperature (18-21 degrees C), a small, pressure-independent Cl(-) efflux was measured. On warming to 37 degrees C, arteries developed pressure-dependent myogenic tone, and this was associated with a pressure-dependent increase in Cl(-) efflux (n = 5). 3. Both myogenic tone and the pressure- and temperature-dependent Cl(-) efflux were abolished on application of 10 microM tamoxifen, a Cl(-) channel blocker (IC(50) 3.75 +/- 0.2 microM). Tamoxifen (10 microM) also prevented contraction to 60 mM K(+), suggesting non-specific effects of tamoxifen (n = 5). 4. Myogenic tone was abolished by 2 microM nimodipine, but Cl(-) efflux was unaffected. In the presence of nimodipine, 10 microM tamoxifen still abolished pressure- and temperature-dependent Cl(-) efflux (n = 3). 5. In summary, a Cl(-) efflux can be measured from rat cerebral arteries, with a temperature dependence that is closely correlated with myogenic contraction. We conclude that Cl(-) efflux through Cl(-) channels contributes to the depolarization associated with myogenic contraction.
Doughty
J M
JM
Department of Physiology, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Langton
P D
PD
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D002536:Cerebral Arteries / Q000378:metabolism*; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D006016:Glycolates / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013629:Tamoxifen / Q000494:pharmacology; D014661:Vasoconstriction / Q000502:physiology*; D014666:Vasomotor System / Q000187:drug effects
D018118:Chloride Channels; D002712:Chlorides; D006016:Glycolates; D013629:Tamoxifen; C015765:MK 473; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid