The Ca-sensitive K channel (KCa channel) plays a key role in buffering pressure-induced constriction of small cerebral arteries. An amplified current through this channel has been reported in vascular smooth muscle cells obtained from hypertensive animals, implying that the expression or properties of KCa channels may be regulated by in vivo blood pressure levels. In this study, we investigated...

Endothelial oxidative stress develops with aging and reactive oxygen species impair endothelium-dependent relaxation (EDR) by decreasing nitric oxide (NO) availability. Endothelial KCa 3.1, which contributes to EDR, is upregulated by H2 O2 . We investigated whether KCa 3.1 upregulation compensates for diminished EDR to NO during aging-related oxidative stress. Previous studies identified that t...

It has been suggested that impairment of smooth muscle cell (SMC) function by alterations in the Ca2+-activated K+ (KCa) channels accounts for the reduction in coronary reserve during left ventricular hypertrophy (LVH). However, this hypothesis has not been fully investigated. The main goal of this study was to assess whether the properties of KCa channels in coronary SMCs were altered during L...

Liu, Xibao, Eduardo Rojas, and Indu S. Ambudkar. Regulation of KCa current by store-operated Ca21 influx depends on internal Ca21 release in HSG cells. Am. J. Physiol. 275 (Cell Physiol. 44): C571–C580, 1998.—This study examines the Ca21 influx-dependent regulation of the Ca21-activated K1 channel (KCa) in human submandibular gland (HSG) cells. Carbachol (CCh) induced sustained increases in the...

Mitochondria regulate intracellular calcium (Ca2+) signals in smooth muscle cells, but mechanisms mediating these effects, and the functional relevance, are poorly understood. Similarly, antihypertensive ATP-sensitive potassium (KATP) channel openers (KCOs) activate plasma membrane KATP channels and depolarize mitochondria in several cell types, but the contribution of each of these mechanisms ...

Hurley, Bernard R., Harold G. Preiksaitis, and Stephen M. Sims. Characterization and regulation of Ca21dependent K1 channels in human esophageal smooth muscle. Am. J. Physiol. 276 (Gastrointest. Liver Physiol. 39): G843– G852, 1999.—We examined the properties of K1 channels in smooth muscle cells dissociated from human esophagus using patch-clamp recording in the cell-attached configuration. Th...

Recent studies have suggested that coronary endothelial cells produce and release nitric oxide (NO), prostaglandin I2, and epoxyeicosatrienoic acids (EETs). These endothelium-derived vasodilators play an important role in the control of coronary vascular tone. However, the mechanism by which these endothelium-derived vasodilators cause relaxation of coronary arterial smooth muscle has yet to be...

Human cardiac fibroblasts (HCFs) have various voltage-dependent K(+) channels (VDKCs) that can induce apoptosis. Hydrogen peroxide (H2O2) modulates VDKCs and induces oxidative stress, which is the main contributor to cardiac injury and cardiac remodeling. We investigated whether H2O2 could modulate VDKCs in HCFs and induce cell injury through this process. In whole-cell mode patch-clamp recordi...

Guanosine-3',5'-cyclic monophosphate (cGMP)-dependent protein kinase (cGMP-PK) plays a central role in the mediation of the vasodilator response to nitric oxide (NO) and other nitrovasodilators. It is unclear whether cGMP-PK affects calcium-activated potassium channels (KCa channels) or any other type of ion channel in smooth muscle. We provide here the first direct evidence that cGMP-PK can ac...

The regulation of calcium-activated K (KCa) channels by a G protein-mediated mechanism was studied. KCa channels were reconstituted in planar lipid bilayers by fusion of membrane vesicles from rat or pig myometrium. The regulatory process was studied by exploring the actions of GTP and GTP gamma S on single channel activity. KCa channels had a conductance of 260 +/- 6 pS (n = 25, +/- SE, 250/50...