Alterations in cellular Ca and Na regulation play a role in the pathogenesis of essential hypertension. Using peripheral lymphocytes from 68 normal persons, we observed the following relationships for major cellular Ca regulatory parameters. Among men and women, Na-Ca exchanger activity was positively correlated with the resting cytosolic free Ca ([Ca]c) (r50.43, P50.0003), and the resting [Ca ...

We have previously shown that disabling forward-mode Na(+)-Ca(2+) exchange in amacrine cells greatly prolongs the depolarization-induced release of transmitter. To investigate the mechanism for this, we imaged [Ca(2+)](i) in segments of dendrites during depolarization. Removal of [Na(+)](o) produced no immediate effect on resting [Ca(2+)](i) but did prolong [Ca(2+)](i) transients induced by bri...

Zhang, Shen, Jason X.-J. Yuan, Kim E. Barrett, and Hui Dong. Role of Na /Ca exchange in regulating cytosolic Ca in cultured human pulmonary artery smooth muscle cells. Am J Physiol Cell Physiol 288: C245–C252, 2005. First published September 29, 2004; doi:10.1152/ajpcell.00411.2004.—A rise in cytosolic Ca concentration ([Ca ]cyt) in pulmonary artery smooth muscle cells (PASMC) is an important s...

The whole cell patch-clamp technique, in both standard and perforated patch configurations, was used to study the influence of Na+-Ca++ exchange on rundown of voltage-gated Ca++ currents and on the duration of tail currents mediated by Ca++-dependent Cl- channels. Ca++ currents were studied in GH3 pituitary cells; Ca++-dependent Cl- currents were studied in AtT-20 pituitary cells. Na+-Ca++ exch...

In fura 2-loaded N1E-115 cells, regulation of intracellular Ca(2+) concentration ([Ca(2+)](i)) following a Ca(2+) load induced by 1 microM thapsigargin and 10 microM carbonylcyanide p-trifluoromethyoxyphenylhydrazone (FCCP) was Na(+) dependent and inhibited by 5 mM Ni(2+). In cells with normal intracellular Na(+) concentration ([Na(+)](i)), removal of bath Na(+), which should result in reversal...

Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activ...

The effect of varying Nao and Nai on Ca efflux while maintaining the ratio Nao/Nai constant was explored in squid giant axons dialyzed with and without ATP. In the absence of ATP, the Ca efflux increased 3.4 +/- 0.2-fold when the Nao/Nai concentrations were reduced from 440/80 to 110/20 mM. In the presence of ATP a similar change did not have an appreciable effect. The inhibition of Ca efflux p...

There are considerable data to support the general hypothesis that accumulation of [Na]i during ischemia and early reperfusion leads, via Na/Ca exchange, to elevated [Ca]i, resulting in myocardial damage.1–10 Despite the strong support for the general aspects of this hypothesis, there is controversy regarding some details that have important implications for the design of therapeutic interventi...

A model is developed which requires the binding of 4 Na+ to a carrier before a Ca binding site is induced on the opposite side of the membrane. Upon binding Ca, this carrier translocates Na and Ca. The existence of partially Na-loaded but nonmobile forms for the carrier (NaX, Na2X, Na3X) suffices to explain both the activating and the inhibitory effects of Na on the Ca transport reaction. Analy...