Alpha2-Adrenoceptor activation increases calcium channel currents in single vascular smooth muscle cells isolated from human omental resistance arteries.

Abstract

Single cells were freshly isolated from human omental resistance arteries using an enzymatic dispersion technique. Calcium channel currents (IBa) were recorded using whole cell voltage clamp techniques with Ba2+ as the charge carrier. BHT 933, a selective alpha2-adrenoceptor agonist, increased IBa. The effect of BHT 933 was reversible following washout. The action of BHT 933 was blocked by yohimbine. Pretreatment of tissues with pertussis toxin for 18 h or inclusion of GDP-beta-S in the intracellular patch pipette solution also prevented the BHT 933-induced rise in IBa, but had no effect on IBa in the absence of BHT 933. Activation of alpha2-adrenoceptors in human vascular smooth muscle cells increases IBa by a mechanism involving a pertussis toxin-sensitive G protein.