Key result
Quinidine (>50 microM) inhibited Ca2+ uptake induced by lowering external Na+ but had little effect on Ca2+ efflux, suggesting it is not a specific inhibitor of Na+-Ca2+ exchange in rat cardiac myocytes.
Quinidine inhibits Ca2+ entry through the cellular membrane rather than specifically inhibiting Na+-Ca2+ exchange in rat cardiac myocytes.
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Caution advised against quinidine as a selective Na+-Ca2+ exchange probe in myocytes; challenges assumptions in prior pharmacologic studies.
Désilets et al. (1984) studied Isolated adult rat cardiac cells. Quinidine vs. Lidocaine / varying external Na+ concentrations was evaluated on Na+-dependent Ca2+ transport (45Ca2+ uptake and efflux). Quinidine (>50 microM) inhibited Ca2+ uptake induced by lowering external Na+ but had little effect on Ca2+ efflux, suggesting it is not a specific inhibitor of Na+-Ca2+ exchange in rat cardiac myocytes.
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