Stimulation of fura-2-loaded human neutrophils with formylmethionyl-leucyl-phenylalanine (FMLP) or ionomycin elevated the cytosolic free Ca2+ concentration, [Ca2+], to a maintained elevated level. Activation of protein kinase C (C-kinase) with phorbol 12-myristate 13-acetate, 4 beta-phorbol 12,13-didecanoate or dioctanoylglycerol caused decreases in [Ca2+]i from this level. 4 alpha-Phorbol dide...

Extracellular nucleotides cause elevation of cytosolic free Ca2+ concentration ([Ca2+](i)) in osteoclasts, although the sources of Ca2+ are uncertain. Activation of P2Y receptors causes Ca2+ release from stores, whereas P2X receptors are ligand-gated channels that mediate Ca2+ influx in some cell types. To examine the sources of Ca2+, we studied osteoclasts from rat and rabbit using fura 2 fluo...

We have found that human chymase produces a 31-amino acid endothelin [ET-1-(1-31)] from the 38-amino acid precursor (Big ET-1). We examined the mechanism of synthetic ET-1-(1-31)-induced intracellular Ca2+ signaling in cultured human coronary artery smooth muscle cells. ET-1-(1-31) increased the intracellular free Ca2+concentration ([Ca2+]i) in a concentration-dependent manner (10-14-10-10M). T...

Excitation-contraction coupling in skeletal muscle requires the release of intracellular calcium ions (Ca2+) through ryanodine receptor (RyR1) channels in the sarcoplasmic reticulum. Half of the RyR1 channels are activated by voltage-dependent Ca2+ channels in the plasma membrane. In planar lipid bilayers, RyR1 channels exhibited simultaneous openings and closings, termed "coupled gating." Addi...

Fura-2 digital imaging microfluorimetry was used to evaluate the Ca2+ signals generated in single clonal human neuroepithelioma cells (SK-N-MCIXC) in response to agonists that stimulate phosphoinositide hydrolysis. Addition of optimal concentrations of either endothelin-1 (ET-1), ATP, oxotremorine-M (Oxo-M), or norepinephrine (NE) all resulted in an increase in the concentration of cytosolic ca...

The presence of L-type Ca2+ channels at the frog neuromuscular junction (nmj) was studied by monitoring changes in intracellular Ca2+ evoked in presynaptic terminals and perisynaptic Schwann cells (PSCs) and by studying the distribution of Ca2+ channels using a monoclonal antibody directed against the alpha 2/delta subunit of L channels. L-type Ca2+ channel agonist and antagonist had no effect ...

During early development, intracellular Ca2+ mobilization is not only essential for fertilization, but has also been implicated during other meiotic and mitotic events, such as germinal vesicle breakdown (GVBD) and nuclear envelope breakdown (NEBD). In this study, the roles of intracellular and extracellular Ca2+ were examined during meiotic maturation and reinitiation at parthenogenetic activa...

Microspectrofluorometry of fura-2 was utilized to monitor [Ca2+]i in single acinar cells stimulated with a cholinergic agonist and cholecystokinin. A similar amplitude of agonist induced Ca mobilization between single cell and populational approaches was observed. New findings in single cells not observable in populations of cells include: 1) the maintenance of a sustained elevation in [Ca2+]i ...

The coexistence of F−, Ca2+, nitrates, and other pollutants in water body has aroused widespread concern. In this research, a novel quartz sand biofilm reactor was established, aiming to study the key factors different carbon nitrogen (C/N) ratios (5:1, 4:1, 3:1), initial Ca2+ concentration (180 mg L−1, 144 108 L−1), hydraulic retention time (HRT) (4 h, 6 8 h) on simultaneous precipitation, F− ...

The objective of this study was to evaluate the contribution of mitochondria to the clearance of Ca2+ loads induced by glutamate or 25 mM K+ pulses. The mitochondrial Ca2+ uptake was suppressed by application of 0.5 microM antimycin A or 3-5 mM NaCN in combination with 2.5 micrograms/ml oligomycin. In most cells such treatments both in the presence and in the absence of external Na+ failed to a...