Antonio G. García

Artalejo CR

Bittner MA

Enrique Calvo-Gallardo

José-Carlos Fernández-Morales

Juan-Alberto Arranz-Tagarro

Juan-Fernando Padín

Lee SL

Luís Gandía

Matsuda T

Ricardo de Pascual

Román Olivares

Stefan Vestring

The activity of the plasmalemmal Na+/Ca2+exchanger (NCX) is highly sensitive to temperature. We took advantage of this fact to explore here the effects of the NCX blocker KB-R7943 (KBR) at 22 and 37°C on the kinetics of Ca2+currents ( ICa), cytosolic Ca2+([Ca2+]c) transients, and catecholamine release from bovine chromaffin cells (BCCs) stimulated with high K+, caffeine, or histamine. At 22°C, the effects of KBR on those parameters were meager or nil. However, at 37°C whereby the NCX is moving Ca2+at a rate fivefold higher than at 22°C, various of the effects of KBR were pronounced, namely: 1) no effects on ICa; 2) reduction of the [Ca2+]ctransient amplitude and slowing down of its rate of clearance; 3) blockade of the K+-elicited quantal release of catecholamine; 4) blockade of burst catecholamine release elicited by K+; 5) no effect on catecholamine release elicited by short K+pulses (1–2 s) and blockade of the responses produced by longer K+pulses (3–5 s); and 6) potentiation of secretion elicited by histamine or caffeine. Furthermore, the more selective NCX blocker SEA0400 also potentiated the secretory responses to caffeine. The results suggest that at physiological temperature the NCX substantially contributes to shaping the kinetics of [Ca2+]ctransients and the exocytotic responses elicited by Ca2+entry through Ca2+channels as well as by Ca2+release from the endoplasmic reticulum.</jats:p

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AJP Cell Physiology

Plasmalemmal sodium-calcium exchanger shapes the calcium and exocytotic signals of chromaffin cells at physiological temperature

Plasmalemmal sodium-calcium exchanger shapes the calcium and exocytotic signals of chromaffin cells at physiological temperature

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