Properties of BK_Ca Channels in Oral Keratinocytes

Abstract

Keratinocytes are important for epithelial antimicrobial barrier function. The activity of ion channels can affect the proliferation of keratinocytes. Little is known about Ca2+-activated K+ currents in these cells. Ion currents in normal human oral keratinocytes were characterized with a patch-clamp technique. In whole-cell configuration, depolarizing pulses evoked K+ outward currents (I(K)) in oral keratinocytes. Iberiotoxin (200 nM) and paxilline (1 microM) suppressed I(K); however, neither apamin (200 nM) nor 5-hydroxydecanoate (30 microM) had any effects on it. Caffeic acid phenethyl ester, a compound of honeybee propolis, increased I(K) with an EC50 value of 12.8 +/- 1.2 microM. In inside-out patches, a BK(Ca) channel was observed in keratinocytes, but not in oral squamous carcinoma (OCE-M1) cells. Caffeic acid phenethyl ester or cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate applied to the intracellular surface of a detached patch increased BK(Ca)-channel activity. The results demonstrate that the properties of BK(Ca) channels in normal human oral keratinocytes are similar to those described in other types of cells. Caffeic acid derivatives can also stimulate BK(Ca)-channel activity directly.

Nitric Oxide Stimulates a Large-Conductance Ca²⁺-Activated K⁺ Channel in Human Skin Fibroblasts through Protein Kinase G Pathway

“…The whole-cell K + current showed many previously reported features of the BK Ca current: enhancement by NS1619 [18] , inhibition by IBTX [19,20] , activation at -20 mV, and the noninactivating, oscillating properties when exposed to strong depolarization voltage [14] . Large conductance, Ca 2+ dependence, and inhibition by IBTX of the single channel was similar to the BK Ca channels in other single-channel experiments with human fi broblasts [21] , vascular smooth muscle cells [22] , oral keratinocytes [20] , and endothelial cells [5] . Therefore, the present data strongly suggest that the BK Ca chan- nel currents constitute the principal components of the outward current.…”

Arecoline inhibits intermediate-conductance calcium-activated potassium channels in human glioblastoma cell lines

“…In continued presence of ARE, further addition of CAPE (3 mM) significantly elevated channel activity to 0.10270.013 (n¼ 9, Po0.05) without any changes in single-channel conductance of the channel, while further addition of verruculogen (1 mM) decreased channel activity to 0.01570.004 (n¼9, Po0.05). CAPE is an opener of BK Ca channels and verruculogen is potent in suppressing these channels (Wu et al, 2003;Shieh et al, 2005). The data strongly indicates that, unlike the activity of IK Ca channels, the BK Ca channels inherent in U373 cells are not sensitive to inhibition by ARE.…”

“…Cells were cultured in keratinocyte serum-free medium (Invitrogen), with low Ca 2 þ (0.1 mM) on flasks coated with rat-tail collagen. Cells were grown in 50-mL plastic culture flasks in a humidified environment of 5% CO 2 /95% air at 37 1C (Shieh et al, 2005). All patients signed informed consent, and the study protocol was approved by a local ethical committee.…”

“…ARE was reported to exert stimulatory effects on phagocytic activity or the production of connective-tissue growth factors in human buccal keratinocytes (Shieh et al, 2005;Deng et al, 2009). The fibroblast IK Ca -channel activity has been reported to be essential for cell growth (Peña and Rane, 1999).…”

The effects of magnetite (Fe3O4) nanoparticles on electroporation-induced inward currents in pituitary tumor (GH3) cells and in RAW 264.7 macrophages

“…Voltage-clamp recordings were made in whole-cell configuration using an RK-400 amplifier (Bio-Logic, Claix, France) or an Axopatch™ 200B amplifier (Molecular Devices, Sunnyvale, CA). 11,12,14 The I MEP was induced as documented previously. 15 …”