Two different families of Na+/Ca2+ exchangers, K+-independent NCX and K+-dependent NCKX, are known. Exploiting the outward K+ gradient, NCKX is able to extrude Ca2+ more efficiently than NCX, even when the Na+ gradient is reduced. The NCKX, which was originally thought to be limited to the retinal photoreceptor, was shown recently to be widely distributed in the brain. We investigated the contr...

Voltage-gated Na and Ca2+ channels comprise distinct ion channel superfamilies, yet the carboxy tails of these channels exhibit high homology, hinting at a long-shared and purposeful module. For different Ca2+ channels, carboxyl-tail interactions with calmodulin do elaborate robust and similar forms of Ca2+ regulation. However, Na channels have only shown subtler Ca2+ modulation that differs am...

The effects of pronase and/or SDS pretreatment on Na+-Ca2+ exchange were studied in rat brain microsomal membranes. Pronase in concentrations that liberated 11% of the membrane proteins stimulated the Na+-Ca2+ exchange. When about 24% of the proteins were split off, the results did not differ from those in control experiments. When 40% or more of the proteins were solubilized, Na+-Ca2+ exchange...

To study the regulation of [Na+]i and [Ca2+]i during myocardial ischemia/reperfusion, [Na+]i and [Ca2+]i were measured simultaneously using guinea pig ventricular myocytes which were dual-loaded with SBFI/AM and fluo-3/AM. It was suggested that: (1) [Na+]i increased during metabolic inhibition (MI: 3.3 mM amytal and 5 microM CCCP) by both the activated Na+ influx via Na+/H+ exchange and the sup...

Propagation of action potentials in axons and dendrites increases intracellular Na+ ([Na+]i) and Ca2+ concentrations ([Ca2+]i). While the importance of [Ca2+]i in synaptic transmission is well established, a possible functional role of [Na+]i is unclear. In cultured hippocampal cells, [Na+]i was increased by veratridine. We have then measured spontaneous excitatory postsynaptic currents (sEPSCs...

To determine whether there are abnormalities in myocyte excitation-contraction coupling and intracellular Ca2+concentration ([Ca2+]i) homeostasis in pacing-induced heart failure (PF), we measured L-type Ca2+ current ( I Ca,L) and Na+/Ca2+exchanger current ( I Na/Ca) with voltage clamp and measured intracellular Na+ concentration ([Na+]i) and [Ca2+]iwith the use of sodium-binding benzofuran isop...

Na(+)-Ca2+ exchange has been shown to contribute to reperfusion- and reoxygenation-induced cellular Ca2+ loading and damage in the heart. Despite the fact that both [Na+]i and [Ca2+]i have been documented to rise during ischemia and hypoxia, it remains unclear whether the rise in [Ca2+]i occurring during hypoxia is linked to the rise in [Na+]i via Na(+)-Ca2+ exchange before reoxygenation and ho...

Ca2+ transport mechanisms were investigated using membrane vesicles prepared from guinea pig brain synaptosomes by hypotonic lysis. Two major mechanisms of Ca2+ transport exist, Na+-Ca2+ exchange and ATP-dependent Ca2+ uptake. A third although minor component of Ca2+ uptake occurs under hyperpolarizing conditions (determined by increased uptake of [3H]tetraphenylphosphonium+). Na+-Ca2+ exchange...

We measured [Ca2+]i and [Na+]i in isolated transgenic (TG) mouse myocytes overexpressing the Na+-Ca2+ exchanger and in wild-type (WT) myocytes. In TG myocytes, the peak systolic level and amplitude of electrically stimulated (ES) [Ca2+]i transients (0.25 Hz) were not significantly different from those in WT myocytes, but the time to peak [Ca2+]i was significantly prolonged. The decline of ES [C...