In striated muscle, the sarcoplasmic reticulum (SR) Ca2+ release/ryanodine receptor (RyR) channel provides the pathway through which stored Ca2+ is released into the myoplasm during excitation-contraction coupling. Various luminal Ca2+-binding proteins are responsible for maintaining the free [Ca2+] at 10(-3)-10(-4) M in the SR lumen; in skeletal-muscle SR, it is mainly calsequestrin. Here we s...

Ca2+ channels from lipid and proteolipid fractions of cisplatin-sensitive and cisplatin-resistant cells were reconstituted and characterized in bilayer lipid membranes formed at the tips of patch-clamp micropipets. The characteristics of the Ca2+ channels were typical for the endoplasmic reticulum membrane channel activity. They had a relatively large unit conductance and were modified by typic...

SK2- and KV4.2-containing K+ channels modulate evoked synaptic potentials in CA1 pyramidal neurons. Each is coupled to a distinct Ca2+ source that provides Ca2+-dependent feedback regulation to limit AMPA receptor (AMPAR)- and NMDA receptor (NMDAR)-mediated postsynaptic depolarization. SK2-containing channels are activated by Ca2+ entry through NMDARs, whereas KV4.2-containing channel availabil...

Modulation of presynaptic voltage-dependent Ca2+ channels is a major means of controlling neurotransmitter release. The CaV2.2Ca2+ channel subunit contains several inhibitory interaction sites for Gβγ subunits, including the amino terminal (NT) and I-II loop. The NT and I-II loop have also been proposed to undergo a G protein-gated inhibitory interaction, whilst the NT itself has also been prop...

Growing evidence suggests that the main olfactory epithelium contains a subset of olfactory sensory neurons (OSNs) responding to pheromones. One candidate subpopulation expresses the calcium activated cation channel TRPM5 (transient receptor potential channel M5). Using GFP driven by the TRPM5 promoter in mice, we show that this subpopulation responds to putative pheromones, urine, and major hi...

Neurite outgrowth from isolated, identified molluscan (Helisoma trivolvis) neurons in culture can be suppressed by neurotransmitters and electrical activity, both of which increase intraneuronal Ca2+ levels (Haydon et al., 1984; Cohan et al., 1986, 1987). We explored the possibility of a causal relationship between Ca2+ influx from the cell exterior and neurite outgrowth using a spectrum of pha...

The Ca2+ and voltage dependence of Ca(2+)-activated Cl- currents in rat parotid acinar cells was examined with the whole-cell patch clamp technique. Acinar cells were dialyzed with buffered free Ca2+ concentrations ([Ca2+]i) from < 1 nM to 5 microM. Increasing [Ca2+]i induced an increase in Cl- current at all membrane potentials. In cells dialyzed with [Ca2+]i > 25 nM, depolarizing test pulses ...

The relationship between extracellular Ca2+ concentration and EPSC amplitude was investigated at excitatory autapses on cultured hippocampal neurons. This relationship was steeply nonlinear, implicating the cooperative involvement of several Ca2+ ions in the release of each vesicle of transmitter. The cooperativity was estimated to be 3.1 using a power function fit and 3.3 using a Hill equation...

Fluspirilene binds with high affinity to a single class of sites in purified porcine cardiac sarcolemmal membrane vesicles at a Kd of 0.6 nM and a Bmax that is in approximately 1:1 stoichiometry with other Ca2+ entry blocker receptors. Fluspirilene binding is modulated by various classes of L-type Ca2+ channel effectors. Metal ion channel inhibitors (e.g. Cd2+) stimulate binding primarily by in...

The aim of this study was to investigate mechanisms by which adiponectin influences vascular Ca2+ signaling, K+ channel activity and thus contractile tone of small arteries. Vasodilation to adiponectin was studied in mesenteric resistance arteries constricted with intraluminal pressure. Ca2+ signals were characterized using high speed confocal microscopy of intact arteries. Patch clamp investig...