HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 290/1/H373    most recent 00613.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Saini, H. K. Articles by Dhalla, N. S. Search for Related Content PubMed PubMed Citation Articles by Saini, H. K. Articles by Dhalla, N. S.

Involvement of Na⁺/Ca²⁺ exchanger in catecholamine-induced increase in intracellular calcium in cardiomyocytes

Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada

Submitted 8 June 2005 ; accepted in final form 5 September 2005

Although sarcolemmal (SL) Na⁺/Ca²⁺ exchanger is known to regulate the intracellular Ca²⁺ concentration ([Ca²⁺]_i), its involvement in catecholamine-induced increase in [Ca²⁺]_i is not fully understood. To gain some information in this regard, isolated rat cardiomyocytes were treated with different agents, which are known to modify Ca²⁺ movements, in the absence or presence of a -adrenoceptor agonist, isoproterenol, and [Ca²⁺]_i in cardiomyocytes was determined spectrofluorometrically with fura-2 AM. Treatment with isoproterenol did not alter [Ca²⁺]_i in quiescent cardiomyocytes, whereas the ATP (purinergic receptor agonist)-induced increase in [Ca²⁺]_i was significantly potentiated by isoproterenol. Unlike ryanodine and cyclopiazonic acid, which affect the sarcoplasmic reticulum function, SL L-type Ca²⁺ channel blockers verapamil and diltiazem, as well as a SL Ca²⁺-pump inhibitor, vanadate, caused a significant depression in the isoproterenol-induced increase in [Ca²⁺]_i. The SL Na⁺/Ca²⁺ exchange blockers amiloride, Ni²⁺, and KB-R7943 also attenuated the isoproterenol-mediated increase in [Ca²⁺]_i. Combination of KB-R7943 and verapamil showed additive inhibitory effects on the isoproterenol-induced increase in [Ca²⁺]_i. The isoproterenol-induced increase in [Ca²⁺]_i in KCl-depolarized cardiomyocytes was augmented by low Na⁺; this augmentation was significantly depressed by treatment with KB-R7943. The positive inotropic action of isoproterenol in isolated hearts was also reduced by KB-R7943. These data suggest that in addition to SL L-type Ca²⁺ channels, SL Na⁺/Ca²⁺ exchanger seems to play an important role in catecholamine-induced increase in [Ca²⁺]_i in cardiomyocytes.

sodium/calcium exchanger; L-type calcium channels; calcium-pump adenosine triphosphatase; calcium-release channels; cardiomyocyte calcium handling

This article has been cited by other articles:

				H. K. Saini and N. S. Dhalla Sarcolemmal cation channels and exchangers modify the increase in intracellular calcium in cardiomyocytes on inhibiting Na+-K+-ATPase Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H169 - H181. [Abstract] [Full Text] [PDF]

				Z. Makazan, H. K. Saini, and N. S. Dhalla Role of oxidative stress in alterations of mitochondrial function in ischemic-reperfused hearts Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1986 - H1994. [Abstract] [Full Text] [PDF]

				H. K. Saini and N. S. Dhalla Modification of intracellular calcium concentration in cardiomyocytes by inhibition of sarcolemmal Na+/H+ exchanger Am J Physiol Heart Circ Physiol, December 1, 2006; 291(6): H2790 - H2800. [Abstract] [Full Text] [PDF]

				Y.-J. Xu, H. K. Saini, M. Zhang, V. Elimban, and N. S. Dhalla MAPK activation and apoptotic alterations in hearts subjected to calcium paradox are attenuated by taurine Cardiovasc Res, October 1, 2006; 72(1): 163 - 174. [Abstract] [Full Text] [PDF]