The sodium-calcium exchanger is a mechanosensitive transporter

John P. Reeves, Maha Abdellatif, Madalina Condrescu

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


This report describes the influence of fluid flow and osmotically induced volume changes on Na+-Ca2 exchange (NCX) activity in transfected CHO cells. Exchange activity was measured as Na+-dependent Ca2 or Ba2 fluxes using the fluorescent probe fura-2. When exchange activity was initiated by superfusing Ba2+-containing solutions over the cells for a 20 s interval, a high rate of Ba2+ uptake was observed while the solution was being applied but the rate of Ba2+ uptake declined > 10-fold when the solution flow ceased. Ba2+ efflux in exchange for extracellular Na+ or Ca2+ (Ba2+-Ca2+ exchange) was similarly biphasic. During NCX-mediated Ca2+ uptake, a rapid increase in cytosolic [Ca2+ ]to a peak value occurred, followed by a decline in [Ca2+] i to a lower steady-state value after solution flow ceased. When NCX activity was initiated by an alternate procedure that minimized the duration of solution flow, the rapid phase of Ba2+ influx was greatly reduced in magnitude and Ca2+ uptake became nearly monophasic. Solution superfusion did not produce any obvious changes in cell shape or volume. NCX-mediated Ba2+ and Ca2+ influx were also sensitive to osmotically induced changes in cell volume. NCX activity was stimulated in hypotonic media and inhibited in hypertonic media; the osmotically induced changes in activity occurred within seconds and were rapidly reversible. We conclude that NCX activity is modulated by both solution flow and osmotically induced volume changes.

Original languageEnglish (US)
Pages (from-to)1549-1563
Number of pages15
JournalJournal of Physiology
Issue number6
StatePublished - Mar 15 2008

All Science Journal Classification (ASJC) codes

  • Physiology


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