The properties of capacitative Ca(2+) influx were studied using the whole-cell patch-clamp technique in crypts isolated from rat distal colon. Store-operated cation influx was evoked by increasing the intracellular buffering capacity for Ca(2+) in the pipette solution; contamination by Cl(-) currents was reduced by the use of NMDG gluconate as the main electrolyte in the pipette solution. The p...

40 41 Intracellular Ca 2+ is critical to the central clock of the suprachiasmatic nucleus (SCN). 42 However, the role of Na + /Ca 2+ exchanger (NCX) in [Ca 2+ ]i homeostasis in the SCN is 43 unknown. Here we show that NCX is an important mechanism for somatic Ca 2+ clearance in 44 the SCN neurons. In control conditions Na + -free solution lowered [Ca 2+ ]i by inhibiting TTX45 sensitive as well ...

Because intracellular [Na(+)] is kept low by Na(+)/K(+)-ATPase, Na(+) dependence is generally considered a property of extracellular enzymes. However, we found that p94/calpain 3, a skeletal-muscle-specific member of the Ca(2+)-activated intracellular "modulator proteases" that is responsible for a limb-girdle muscular dystrophy ("calpainopathy"), underwent Na(+)-dependent, but not Cs(+)-depend...

In order to accurately model soil reclamation with concentrated electrolytes such as CaCl2 or sea water, it must be determined if there is an effect of salinity on the Na-Ca exchange selectivity. A new procedure for determining Na-Ca selectivity in calcareous and gypsiferous soils was used to study the effects of ionic strength and mineralogy on Na-Ca exchange. Four specimen clay minerals and t...

We studied GABAergic signaling in astrocytes of olfactory bulb slices using confocal Ca(2+) imaging and two-photon Na(+) imaging. GABA evoked Ca(2+) transients in astrocytes that persisted in the presence of GABA(A) and GABA(B) receptor antagonists, but were suppressed by inhibition of GABA uptake by SNAP 5114. Withdrawal of external Ca(2+) blocked GABA-induced Ca(2+) transients, and depletion ...

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

(E,Z)-3-((2-Aminoethoxy)imino)androstane-6,17-dione hydrochloride (PST2744) is a novel Na(+)/K(+) pump inhibitor with positive inotropic effects. Compared with digoxin in various experimental models, PST2744 was consistently found to be less arrhythmogenic, thus resulting in a significantly higher therapeutic index. The present work compares the electrophysiological effects of PST2744 and digox...

Na transport across a preparation of sheep omasum was studied. All tissues exhibited a serosa-positive short-circuit current ( I sc), with a range of 1-4 μeq ⋅ h-1 ⋅ cm-2. A Michaelis-Menten-type kinetic was found between the Na concentration and the I sc(Michaelis-Menten constant for transport of Na = 6.7 mM; maximal transport capacity of Na = 4.16 μeq ⋅ h-1 ⋅ cm-2). Mucosal amiloride (1 mM), ...

Xie Y, Ottolia M, John SA, Chen J, Philipson KD. Conformational changes of a Ca -binding domain of the Na /Ca exchanger monitored by FRET in transgenic zebrafish heart. Am J Physiol Cell Physiol 295: C388–C393, 2008. First published June 11, 2008; doi:10.1152/ajpcell.00178.2008.—The Na /Ca exchanger is the major Ca extrusion mechanism in cardiac myocytes. The activity of the cardiac Na /Ca exch...