Cytosolic sodium concentration regulates contractility of cardiac muscle.
The present chapter provides experimental evidence to show that intracellular Na+ concentration regulates cardiac contractility effectively by altering intracellular Ca2+ concentration via the Na-Ca exchange. This steep coupling between the Na+ and Ca2+ electrochemical gradients implies that a change in intracellular Na+ concentration is accompanied by a concomitant change in intracellular Ca2+ concentration (and, therefore, contractility). Under the physiologic conditions, each cardiac action potential alters intracellular Na+ concentration in a dynamic manner. Therefore, Na-Ca exchange can regulate cardiac contraction from a beat-to-beat basis.
Sheu
S S
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Department of Pharmacology, University of Rochester, School of Medicine and Dentistry, New York.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000032:analysis; D003864:Depression, Chemical; D004070:Digitalis; D008012:Lidocaine / Q000494:pharmacology; D009200:Myocardial Contraction; D009206:Myocardium / Q000032:analysis*; D010946:Plants, Medicinal; D010947:Plants, Toxic; D012756:Sheep; D012964:Sodium / Q000032:analysis / Q000502:physiology*; D013268:Stimulation, Chemical
D008012:Lidocaine; D012964:Sodium; D002118:Calcium