Increase in extracellular Mg2+ concentration ([Mg2+]o) reduces Ca2+ accumulation during reoxygenation of hypoxic cardiomyocytes and exerts protective effects. The aims of the present study were to investigate the effect of increased [Mg(2+)](o) on Ca2+ influx and efflux, free cytosolic Ca2+ ([Ca2+]i) and Mg2+ concentrations ([Mg2+]i), Ca2+ accumulation in the presence of inhibitors of mitochond...

The distal convoluted tubule reabsorbs significant amounts of filtered magnesium that is under hormonal control. In this study, we describe the effects of aldosterone on Mg2+ uptake in an immortalized mouse distal convoluted tubule (MDCT) cell line. Intracellular free Mg2+ concentration ([Mg2+]i) was determined on single MDCT cells using microfluorescence with mag-fura 2. To determine Mg2+ entr...

The mechanisms that maintain intracellular Mg concentration at physiologic levels are not fully understood. In this work, we described for the first time, a new method using 25Mg stable isotopes, that allows simultaneous determination of Mg2+ efflux and Mg2+ influx in non-loaded cells at physiological levels of extracellular Mg. Erythrocytes from rats were suspended as a 10% suspension in NaCl ...

The potential difference (PD)-dependent component of transcellular Mg2+uptake in sheep rumen epithelium was studied. Unidirectional28Mg2+fluxes were measured at various transepithelial PD values, and the unidirectional mucosal-to-serosal28Mg2+flux ([Formula: see text]) was correlated with the PD across the apical membrane (PDa) determined by mucosal impalement with microelectrodes. PDa was foun...

Alpha1- and beta-adrenoceptor stimulation elicits Mg2+ extrusion from liver cells in conjunction with hepatic glucose output (T. Fagan and A. Romani. Am J Physiol Gastrointest Liver Physiol 279: G943-G950, 2000.). To characterize the role of intrahepatic glucose on Mg2+ transport, male Sprague-Dawley rats were starved overnight before being anesthetized and used as organ donors. Perfused livers...

The transient receptor potential type V5 channel (TRPV5) is a Ca2+-selective TRP channel important for epithelial Ca2+ transport. Intracellular Mg2+ causes a fast voltage-dependent block of the TRPV5 channel by binding to the selectivity filter. Here, we report that intracellular Mg2+ binding to the selectivity filter of TRPV5 also causes a slower reversible conformational change leading to cha...

13C- and31P-NMR were used in methylene blue-treated human erythrocytes to determine the dependence on intracellular Mg2+ concentration ([Mg2+]i) of the pentose phosphate pathway (PPP), the glycolytic pathway, and adenine nucleotide synthesis. The PPP flux had an [Mg2+]iat half-maximal velocity ([Mg2+]i,0.5) of 0.02 mM, well below the physiological range (0.2-0.7 mM). Flux through the PPP was re...

The role of Mg2+ during the final steps of exocytosis was investigated using rat pheochromocytoma cells (PC12) permeabilized with bacterial pore forming toxins. Concentrations of free Mg2+ between 0.2 and 2 mM slightly lowered the basal but greatly enhanced the [3H]dopamine release elicited by 8 microM free Ca2+. Maximal effects were obtained at approximately 1 mM free Mg2+. At higher concentra...

The sarcoplasmic calcium-binding protein (SCP) of the sandworm Nereis possesses three Ca2(+)-Mg2+ sites but no Ca2(+)-specific site. Binding of Mg2+, but not of Ca2+, displays a marked positive cooperativity. The apparent cooperativity of Ca2+ binding in the presence of Mg2+ results from the allostery in Mg2+ dissociation. Binding of the first Ca2+ or Mg2+ induces all the conformational change,...