TRPC3 has been suggested as a key component of phospholipase C-dependent Ca signaling. Here we investigated the role of TRPC3-mediated Na entry as a determinant of plasmalemmal Na /Ca exchange. Ca signals generated by TRPC3 overexpression in HEK293 cells were found to be dependent on extracellular Na , in that carbachol-stimulated Ca entry into TRPC3 expressing cells was significantly suppresse...

In order to resolve uncertainties as to the mechanisms of toxic action of Cu and the protective effects of water [Ca], juvenile rainbow trout were acclimated to baseline soft water (SW, [Na(+)]=0.07, [Ca(2+)]=0.15, [Mg(2+)]=0.05mmolL(-1)) and then exposed to Cu with or without elevated [Ca] but at constant titratable alkalinity (0.27mmolL(-1)). The 96-h LC50 was 7-fold higher (63.8 versus 9.2μg...

Na-Ca exchange current was measured at various concentrations of internal Na [( Na]i) and Ca [( Ca]i) using intracellular perfusion technique and whole-cell voltage clamp in single cardiac ventricular cells of guinea pig. Internal Ca has an activating effect on Nai-Cao exchange beginning at approximately 10 nM and saturating at approximately 50 nM with a half maximum [Ca]i (Km[Ca]i) of 22 nM (H...

Intracellular ATP supply and ion homeostasis determine neuronal survival and degeneration after ischemic stroke. The present study provides a systematic investigation in organotypic hippocampal slice cultures of the influence of experimental ischemia, induced by oxygen-glucose-deprivation (OGD). The pathways controlling intracellular Na(+) and Ca(2+) concentration ([Na(+)](i) and [Ca(2+)](i)) a...

Chromaffin cells isolated from bovine adrenals and maintained in culture were loaded with 45Ca, and the mechanism of 45Ca efflux from these cells was investigated. During exposure to a Ca-deficient, Mg (1 mM)-containing medium, replacement of NaCl with sucrose, choline Cl, or Tris Cl reduced the rate of 45Ca efflux by approx. 30-40%, showing the presence of a Na-dependent 45Ca efflux mechanism....

Axons freshly dissected from living specimens of the tropical squid Dorytheutis plei have a calcium content of 68 mumol/kg of axoplasm. Fibers stimulated at 100 impulses/s in 100 mM Ca seawater increase their Ca content by 150 mumol/kg.min; axons placed in 3 Ca (choline) seawater increase their Ca content by 12 mumol/kg.min. Axons loaded with 0.2--1.5 mmol Ca/kg of axoplasm extruded Ca with a h...

Before synaptogenesis, early excitability implicating voltage-dependent and transmitter-activated channels is known to be crucial for neuronal development. We previously showed that preplate (PP) neurons of the mouse neocortex express functional Na(+) channels as early as embryonic day 12. In this study, we investigated the role of these Na(+) channels in signaling during early development. In ...

Mast cells rely on Ca(2+) signaling to initiate activation programs leading to release of proinflammatory mediators. The interplay between Ca(2+) release from internal stores and Ca(2+) entry through store-operated Ca(2+) channels has been extensively studied. Using rat basophilic leukemia (RBL) mast cells and murine bone marrow-derived mast cells, we examine the role of Na(+)/Ca(2+) exchangers...

AIMS Contraction of the heart is regulated by electrically evoked Ca(2+) transients (CaTs). H(+) ions, the end products of metabolism, modulate CaTs through direct interactions with Ca(2+)-handling proteins and via Na(+)-mediated coupling between acid-extruding proteins (e.g. Na(+)/H(+) exchange, NHE1) and Na(+)/Ca(2+) exchange. Restricted H(+) diffusivity in cytoplasm predisposes pH-sensitive ...