The expression of voltage-gated calcium (Ca2+) channel activity in brain cells is known to be important for several aspects of neuronal development. In addition, excessive Ca2+ influx has been linked clearly to neurotoxicity both in vivo and in vitro; however, the temporal relationship between the development of Ca2+ channel activity and neuronal survival is not understood. Over a period spanni...

The cardiac type 2 ryanodine receptor (RYR2) is activated by Ca2+-induced Ca2+ release (CICR). The inherent positive feedback of CICR is well controlled in cells, but the nature of this control is debated. Here, we explore how the Ca2+ flux (lumen-to-cytosol) carried by an open RYR2 channel influences its own cytosolic Ca2+ regulatory sites as well as those on a neighboring channel. Both flux-d...

Deoxygenation of sickle cells is known to increase cation permeabilities (Na+, K+, and Ca2+). The possible mechanisms involved in the increased uptake of Ca2+ were investigated: activation of Ca2+ channels, involvement of the anion channel, and the formation of endocytic vacuoles. The Ca2+ channel blocker nifedipine reduced the deoxy-stimulated Ca2+ uptake by about 30% to 40%. The anion channel...

The inositol 1,4,5-trisphosphate (InsP(3)) receptor (InsP3R) is an endoplasmic reticulum-localized Ca2+ -release channel that controls complex cytoplasmic Ca(2+) signaling in many cell types. At least three InsP3Rs encoded by different genes have been identified in mammalian cells, with different primary sequences, subcellular locations, variable ratios of expression, and heteromultimer formati...

A high-conductance (100 pS in 53 mM trans Ca2+) Ca2+ channel was incorporated from heavy-density skeletal muscle sarcoplasmic reticulum (SR) fractions into planar lipid bilayers of the Mueller-Rudin type. cis Ca2+ in the range of 2-950 microM increased open probability (Po) in single channel records without affecting open event lifetimes. Millimolar ATP was found to be as good as or better than...

Ca2+-activated K+ channels from rat muscle transverse tubule membranes were inserted into planar phospholipid bilayers, and the activation of these channels by Ca2+ was studied. On the cytoplasmic side of the channel, calcium ions (in the range 10-100 mumol l-1) increase the opening probability of the channel in a graded way. This 'activation curve' is sigmoid, with an average Hill coefficient ...

The voltage- and Ca2+-activated, large conductance K+ channel (BK, maxi-K) is expressed in the collecting duct system of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical collecting duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa ...

The Ca2+-activated, maxi-K (BK) K+ channel, with low Ca2+-binding affinity, is expressed in the distal tubule of the nephron and contributes to flow-dependent K+ secretion. In the present study we demonstrate that the Ca2+-activated, SK3 (KCa2.3) K+ channel, with high Ca2+-binding affinity, is also expressed in the mouse kidney (RT-PCR, immunoblots). Immunohistochemical evaluations using tubule...

The cell-attached, patch-clamp technique was used to investigate the modulatory role of the neuropeptide SEQPDVDDYLRDVVLQSEEPLY ("SEEPLY") on FMRFamide-activated Ca2+ channels in isolated Lymnaea heart ventricular cells. Both SEEPLY and FMRFamide are encoded on the same neuropeptide gene and are coexpressed in a pair of excitatory motor neurons that innervate the heart. FMRFamide applied alone ...

Voltage-activated Ca2+ channels exist as multigene families that share common structural features. Different Ca2+ channels are distinguished by their electrophysiology and pharmacology and can be classified as either low or high voltage-activated channels. Six alpha1 subunit genes cloned previously code for high voltage-activated Ca2+ channels; therefore, we have used a database search strategy...