Introduction: It has recently been suggested that the KATP channel subunits Kir6.x and BKCa channels exist in the endoplasmic reticulum of cardiomyocytes and neurons. Our previous studies showed the electrophysiological behavior of cation channels in the rough endoplasmic reticulum (RER) of rat hepatocytes. Therefore, we hypothesized that KATP channels and Ca2+-activated potassium channels m...

The cardiac muscle sarcoplasmic reticulum Ca2+ release channel (ryanodine receptor) is a ligand-gated channel that is activated by micromolar cytoplasmic Ca2+ concentrations and inactivated by millimolar cytoplasmic Ca2+ concentrations. The effects of sarcoplasmic reticulum lumenal Ca2+ on the purified release channel were examined in single channel measurements using the planar lipid bilayer m...

Previous studies indicated that stress and glucocorticoids have modulatory effects on acute pain. The aim of present study was to determine the interaction between stress and glucocorticoids with activation of voltage dependent Ca2+ channel on modulation of acute pain in mice. Male albino mice (25-30 g) were used for this experiment. Tail flick and hot plate were used for evaluation of analgesi...

Changes in free cytosolic calcium were measured in UMR-106 cells in response to parathyroid hormone (PTH) stimulation. Bovine PTH-(1-34) induced an increase in [Ca2+]i with the contour of the rise in [Ca2+]i occurring in three successive phases: a rapid increase in [Ca2+]i occurring within seconds, rapid decrement in [Ca2+]i to near-resting levels within 1 min, and slow increment in [Ca2+]i. Ph...

The InsP3R Ca2+ release channel has a biphasic dependence on cytoplasmic free Ca2+ concentration ([Ca2+]i). InsP3 activates gating primarily by reducing the sensitivity of the channel to inhibition by high [Ca2+]i. To determine if relieving Ca2+ inhibition is sufficient for channel activation, we examined single-channel activities in low [Ca2+]i in the absence of InsP3, by patch clamping isolat...

In smooth muscle cells, localized intracellular Ca2+ transients, termed "Ca2+ sparks," activate several large-conductance Ca2+-activated K+ (KCa) channels, resulting in a transient KCa current. In some smooth muscle cell types, a significant proportion of Ca2+ sparks do not activate KCa channels. The goal of this study was to explore mechanisms that underlie fractional Ca2+ spark-KCa channel co...

The central vacuole is the largest Ca2+ store in a mature plant cell. Ca2+ release from this store contributes to Ca2+-mediated intracellular signalling in a variety of physiological responses. However, the routes for vacuolar Ca2+ release are not well characterized. To date, at least two voltage-dependent and two ligand-gated Ca2+-permeable channels have been reported in plant vacuoles. Howeve...

Calcium channels have been suggested to play a major role in the initiation of a large number of signal transduction processes in higher plant cells. However, molecular components of higher plant Ca2+ channels remain unidentified to date. Calcium channel blockers of the phenylalkylamine family and bepridil specifically inhibit Ca2+ influx into carrot (Daucus carota L.) cells. By using a phenyla...

L-type Ca2+ channels select for Ca2+ over sodium Na+ by an affinity-based mechanism. The prevailing model of Ca2+ channel permeation describes a multi-ion pore that requires pore occupancy by at least two Ca2+ ions to generate a Ca2+ current. At [Ca2+] < 1 microM, Ca2+ channels conduct Na+. Due to the high affinity of the intrapore binding sites for Ca2+ relative to Na+, addition of microM conc...