The activation of KCa channels in vascular SMCs. (a) Representative single channel current recordings showing two sets of experiments in which KCa channels were preconditioned with DHS, and either SNP (left panel) or CO (right panel) was subsequently applied. (b) The preconditioning with DHS abolished the effect of SNP on the NPo, but not that of CO. n = 6 (from two batches of cells) for each group. *P < 0.05. Inside-out patches. Membrane potential, –30 mV. The dashed lines beside each trace indicate the closed channel current level.