The relative importance of the Na+/Ca2+exchanger in the initial and terminal phases of relaxation and the decline in the [Ca2+]itransient was investigated in adult rabbit ventricular myocytes loaded with the Ca2+ indicator fluo 3. For electrically stimulated contractions, the peak intracellular Ca2+ concentration ([Ca2+]i) was 700 ± 87 nM and end-diastolic [Ca2+]iwas 239 ± 30 nM (0.25 Hz, 37°C,...

The role of sodium-calcium exchanger in calcium homeostasis in Bergmann glial cells in situ was investigated by monitoring cytoplasmic calcium ([Ca2+]i) and sodium ([Na+]i) concentrations. The [Ca2+]i and [Na+]i transients were measured either separately by using fluorescent indicators fura-2 and SBFI, respectively, or simultaneously using the indicators fluo-3 and SBFI. Since the removal of ex...

The role of intracellular Ca2+ homeostasis in mechanisms of neuronal cell death and cysteine protease activation was investigated in SH-SY5Y human neuroblastoma cells. Cells were incubated in 2 mM EGTA to lower intracellular Ca2+ or 5 mM CaCl2 to raise it. Cell death and activation of calpain and caspase-3 were measured. Both EGTA and excess CaCl2 elicited cell death. EGTA induced DNA laddering...

Activation of phospholipase C in nonexcitable cells causes the release of calcium (Ca2+) from intracellular stores and activation of Ca2+ influx by means of Ca2+ release-activated channels (ICRAC) in the plasma membrane. The molecular identity and the mechanism of ICRAC channel activation are poorly understood. Using the patch-clamp technique, here we describe the plasma membrane Ca2+ channels ...

The Arabidopsis TCH genes, which encode calmodulin-related proteins and a xyloglucan endotransglycosylase, are shown to be up-regulated in expression following cold shock. We investigated a possible role of fluctuations in intracellular calcium ion concentrations ([Ca2+]) in the cold-shock-induced TCH gene expression. Transgenic plants harboring the apoaequorin gene were generated to monitor [C...

Changes in the cytosolic free Ca2+ concentration following cell surface receptor activation have been proposed to mediate a wide variety of cellular responses. Using the specific Ca2+ chelator quin2 as a fluorescent intracellular probe, we measured the Ca2+ levels in the cytosol of clonal rat pituitary cells, GH3 cells. We demonstrate that thyrotropin-releasing hormone (TRH) at nanomolar concen...

We have studied the mechanism of Na+ deprivation-induced catecholamine secretion from freshly isolated bovine adrenal chromaffin cells. Na+ deprivation-induced catecholamine secretion depended on free extracellular Ca2+ concentrations and was almost parallel to 45Ca2+ influx into the cells under various experimental conditions. Furthermore, Na+ deprivation-induced 45Ca2+ influx and catecholamin...

1. We examined the effect of the thiazide diuretic, hydrochlorothiazide, on on intracellular calcium concentration ([Ca2+]i) and tone in guinea-pig mesentery arteries. Vessels were mounted on a microvascular myograph and loaded with the Ca(2+)-sensitive fluorescent dye, Fura-2. 2. Hydrochlorothiazide caused relaxation of noradrenaline-precontracted arteries associated with a fall in [Ca2+]i. Pr...

C62B rat glioma cells respond to muscarinic cholinergic stimulation with transient inositol phosphate formation and phospholipase A2-dependent arachidonic acid liberation. Since phospholipase A2 is a Ca2+-sensitive enzyme, we have examined the role of the agonist-stimulated Ca2+ response in production of the arachidonate signal. The fluorescent indicator fura-2 was used to monitor changes in cy...

Epithelial cadherin (E-cadherin) is a transmembrane receptor that plays a vital role in Ca2+-dependent homotypic cell–cell adhesion processes (Takeichi, 1991). The extracellular domain of E-cadherin contains five tandem repeats of about 100 amino acid residues, and is responsible for recognizing cadherin molecules of the same type in a calcium-dependent manner (for a review, see Alattia et al.,...