The relationship between endothelin-1 (ET-1)-induced stimulation of Na(+)-H+ exchange and intracellular free Ca2+ ([Ca2+]i) was examined in primary cultures of porcine coronary artery smooth muscle cells. Intracellular pH (pHi) and [Ca2+]i were measured using 2,7-bis-carboxyethyl-5(6)-carboxyfluorescein and the acetoxymethyl ester of fura-2 respectively. In HCO3(-)-free buffer (pH = 7.4), ET-1 ...

BACKGROUND/AIMS Alzheimer's disease (AD) is known to be related to alterations in neuronal intracellular calcium activity ([Ca2+]i). The present study revealed the distinct role of leptin in Na+/Ca2+-exchanger activity. METHODS [Ca2+]i was determined utilizing Fura-2 fluorescence. The activity of NCX was measured by removal of extracellular Na+ in the presence of external Ca2+. Na+/Ca2+-excha...

Glucagon-like peptide-1 (GLP-1) elevates the intracellular free calcium concentration ([Ca2+]i) and insulin secretion in a Na+-dependent manner. To investigate a possible role of Na ion in the action of GLP-1 on pancreatic islet cells, we measured the glucose-and GLP-1-induced intracellular Na+ concentration ([Na+]i), [Ca2+]i, and insulin secretion in hamster islet cells in various concentratio...

The Na+/Ca2+ exchange system in rat renal cortex basolateral membrane vesicles was studied. Uptake and efflux of Ca2+ in the membrane vesicles were stimulated by trans-Na+. The enhancement of Ca2+ uptake by the intravesicular greater than extravesicular Na+ gradient was inhibited by ionophores that dissipated the gradient, and was increased by an outside negative membrane potential. Na+-depende...

We investigated the effects of different ischemia-mimetic factors on intracellular Ca2+ concentration ([Ca2+]i). Ventricular myocytes were isolated from adult Wistar rats, and [Ca2+]i was measured using fluorescent indicator fluo-4 AM by confocal microscopy. Intracellular pH was measured using c5-(and-6)-carboxy SNARF-1 AM, a dual emission pH-sensitive ionophore. Myocytes were exposed to hypoxi...

The Na(+)-Ca2+ exchanger from Drosophila was expressed in Xenopus and characterized electrophysiologically using the giant excised patch technique. This protein, termed Calx, shares 49% amino acid identity to the canine cardiac Na(+)-Ca2+ exchanger, NCX1. Calx exhibits properties similar to previously characterized Na(+)-Ca2+ exchangers including intracellular Na+ affinities, current-voltage re...

The P2U purinergic agonist ATP (0.3 mM) elicited an increase in [Ca2+]i due to Ca2+ release from intracellular stores in transfected Chinese hamster ovary cells that express the bovine cardiac Na+/Ca2+ exchanger (CK1.4 cells). The following observations indicate that ATP-evoked Ca2+ release was accompanied by a Ca(2+)-dependent regulatory activation of Na+/Ca2+ exchange activity: Addition of ex...

Correlative studies on transports of Ca2+ and Na+ and the properties of Ca2+ transport were carried out in rat kidney cortex slices. Ouabain had no effect on the Ca2+ transport but did inhibit the Na+ transport extensively. With addition of 2,4-dinitrophenol to the incubation medium, or under the anaerobic conditions, the effluxes of Ca2+ and Na+ were inhibited while the Ca2+ influx was enhance...