Depletion of endoplasmic reticulum Ca2+ stores leads to the entry of extracellular Ca2+ into the cytoplasm, a process termed capacitative or store-operated Ca2+ entry. Partially purified extracts were prepared from the human Jurkat T lymphocyte cell line and yeast in which Ca2+ stores were depleted by chemical and genetic means, respectively. After microinjection into Xenopus laevis oocytes, th...

Hydrogen sulfide (H2S) has a variety of physiological functions. H2S reportedly increases intracellular Ca2+ concentration ([Ca2+]i) in astrocytes. However, the precise mechanism and functional role this increase are not known. Here, we examined effects on [Ca2+]i astrocytes from rat spinal cord whether affects ATP-induced signaling, which is known to be involved synaptic function. Na2S (150 ?M...

Intracellular Ca2+ concentrations ([Ca2+]i) are regulated in a spatiotemporal manner via both entry of extracellular Ca2+ and mobilization of Ca2+ from intracellular stores. Metabotropic glutamate receptor subtype 1 (mGluR1) is a G protein-coupled receptor that stimulates the inositol 1,4,5-trisphosphate-Ca2+ signaling cascade, whereas Cav2.1 is a pore-forming channel protein of P/Q-type voltag...

Antibodies against the T3-antigen receptor complex can activate the human T cell line, Jurkat, to produce interleukin 2 (2-5). This activation is initiated by a receptor-mediated increase in the concentration of free cytoplasmic calcium ions [Ca2+]i (3, 4). In this communication, we investigate the mechanism by which the receptor complex increases [Ca2+ )i in Jurkat cells. The initial receptor-...

The contractile sensitivity of smooth muscle to changes in myoplasmic [Ca2+] is dependent on the form of stimulation. Both myosin phosphorylation and force are less sensitive to increases in [Ca2+]i derived from Ca2+ entry through L-type Ca2+ channels than to increases in [Ca2+] induced by agents which release internal Ca2+ stores. We hypothesized that activation of receptor-operated channels s...

Ca2+ is implicated as a second messenger in the response of stomata to a range of stimuli. However, the mechanism by which stimulus-induced increases in guard cell cytosolic free Ca2+ ([Ca2+]i) are transduced into different physiological responses remains to be explained. Oscillations in [Ca2+]i may provide one way in which this can occur. We used photometric and imaging techniques to examine t...

The mechanisms of Ca2+ entry and their effects on cell function were investigated in cultured chicken osteoclasts and putative osteoclasts produced by fusion of mononuclear cell precursors. Voltage-gated Ca2+ channels (VGCC) were detected by the effects of membrane depolarization with K+, BAY K 8644, and dihydropyridine antagonists. K+ produced dose-dependent increases of cytosolic calcium ([Ca...

The frog brain survives hypoxia with a slow loss of energy charge and ion homeostasis. Because hypoxic death in most neurons is associated with increases in intracellular calcium ([Ca2+]i), we examined the relationship between [Ca2+]i and survival of a mixed population of isolated cells from the forebrain of North American bullfrog Rana catesbeiana tadpoles. Forebrain cells from stage V-XV tadp...

There is increasing evidence for nongenomic steroid effects in various cell types. This study is the first to demonstrate that 17 beta-estradiol (E2) exerts a direct nongenomic effect on maturing human oocytes by inducing a series of transient increases in the intracellular free calcium concentration ([Ca2+]i). This effect of E2 appeared to be specific and was mediated by steroid action on the ...

Our aim was to measure calpain protease activity during increases in cytosolic free calcium (Ca2+J after addition of extracellular ATP. The calpain protease substrate t-butoxycarbonyl-Leu-Met-7-amino-4-chloromethylcoumarin was synthesized. Nonfluorescent tbutoxycarbonyl-Leu-Met-7-amino-4-chloromethylcoumarin diffuses into the cell where it is conjugated to glutathione forming t-butoxycarbonyl-L...