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: 288/1/C195    most recent 00183.2004v1 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 (13) Citing Articles via Google Scholar Google Scholar Articles by Huang, J. Articles by Tibbits, G. F. Search for Related Content PubMed PubMed Citation Articles by Huang, J. Articles by Tibbits, G. F.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Na⁺/Ca²⁺ exchange activity in neonatal rabbit ventricular myocytes

¹Cardiac Membrane Research Laboratory, Simon Fraser University, Burnaby, British Columbia; ²Cardiovascular Sciences, BC Research Institute for Children's and Women's Health, Vancouver, British Columbia, Canada; and ³Laboratorio de Fisiología Celular, Servei de Cardiología, Hospital de Sant Pau, Barcelona, Spain

Submitted 12 April 2004 ; accepted in final form 10 August 2004

Much less is known about the contributions of the Na⁺/Ca²⁺ exchanger (NCX) and sarcoplasmic reticulum (SR) Ca²⁺ pump to cell relaxation in neonatal compared with adult mammalian ventricular myocytes. Based on both biochemical and molecular studies, there is evidence of a much higher density of NCX at birth that subsequently decreases during the next 2 wk of development. It has been hypothesized, therefore, that NCX plays a relatively more important role for cytosolic Ca²⁺ decline in neonates as well as, perhaps, a role in excitation-contraction coupling in reverse mode. We isolated neonatal ventricular myocytes from rabbits in four different age groups: 3, 6, 10, and 20 days of age. Using an amphotericin-perforated patch-clamp technique in fluo-3-loaded myocytes, we measured the caffeine-induced inward NCX current (I_NCX) and the Ca²⁺ transient. We found that the integral of I_NCX, an indicator of SR Ca²⁺ content, was greatest in myocytes from younger age groups when normalized by cell surface area and that it decreased with age. The velocity of Ca²⁺ extrusion by NCX (V_NCX) was linear with [Ca²⁺] and did not indicate saturation kinetics until [Ca²⁺] reached 1–3 µM for each age group. There was a significantly greater time delay between the peaks of I_NCX and the Ca²⁺ transient in myocytes from the youngest age groups. This observation could be related to structural differences in the subsarcolemmal microdomains as a function of age.

ontogeny of cardiac excitation-contraction coupling; sodium/calcium exchanger; cytosolic calcium concentration; subsarcolemmal calcium concentration; sarcoplasmic reticulum calcium content

This article has been cited by other articles:

				B. Liang, F. Chung, Y. Qu, D. Pavlov, T. E. Gillis, S. B. Tikunova, J. P. Davis, and G. F. Tibbits Familial hypertrophic cardiomyopathy-related cardiac troponin C mutation L29Q affects Ca2+ binding and myofilament contractility Physiol Genomics, April 1, 2008; 33(2): 257 - 266. [Abstract] [Full Text] [PDF]

				J. Huang, L. Hove-Madsen, and G. F. Tibbits Ontogeny of Ca2+-induced Ca2+ release in rabbit ventricular myocytes Am J Physiol Cell Physiol, February 1, 2008; 294(2): C516 - C525. [Abstract] [Full Text] [PDF]

				J. Huang, L. Hove-Madsen, and G. F. Tibbits SR Ca2+ refilling upon depletion and SR Ca2+ uptake rates during development in rabbit ventricular myocytes Am J Physiol Cell Physiol, December 1, 2007; 293(6): C1906 - C1915. [Abstract] [Full Text] [PDF]

				G. Lin, G. P. Craig, L. Zhang, V. G. Yuen, M. Allard, J. H. McNeill, and K. M. MacLeod Acute inhibition of Rho-kinase improves cardiac contractile function in streptozotocin-diabetic rats Cardiovasc Res, July 1, 2007; 75(1): 51 - 58. [Abstract] [Full Text] [PDF]

				T. Namiki, R. W. Joyner, and M. B. Wagner Developmental changes in time course of recovery from inactivation in L-type calcium currents of rabbit ventricular myocytes Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H295 - H303. [Abstract] [Full Text] [PDF]

				J. Huang, C. van Breemen, K.-H. Kuo, L. Hove-Madsen, and G. F. Tibbits Store-operated Ca2+ entry modulates sarcoplasmic reticulum Ca2+ loading in neonatal rabbit cardiac ventricular myocytes Am J Physiol Cell Physiol, June 1, 2006; 290(6): C1572 - C1582. [Abstract] [Full Text] [PDF]

				J. Huang, L. Xu, M. Thomas, K. Whitaker, L. Hove-Madsen, and G. F. Tibbits L-type Ca2+ channel function and expression in neonatal rabbit ventricular myocytes Am J Physiol Heart Circ Physiol, June 1, 2006; 290(6): H2267 - H2276. [Abstract] [Full Text] [PDF]

				T. E. Gillis, B. Liang, F. Chung, and G. F. Tibbits Increasing mammalian cardiomyocyte contractility with residues identified in trout troponin C Physiol Genomics, June 16, 2005; 22(1): 1 - 7. [Abstract] [Full Text] [PDF]