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: 291/5/H2362    most recent 00070.2006v1 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 (10) Citing Articles via Google Scholar Google Scholar Articles by Grandy, S. A. Articles by Howlett, S. E. Search for Related Content PubMed PubMed Citation Articles by Grandy, S. A. Articles by Howlett, S. E.

Cardiac excitation-contraction coupling is altered in myocytes from aged male mice but not in cells from aged female mice

Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada

Submitted 17 January 2006 ; accepted in final form 19 May 2006

This study characterized age-related alterations in excitation-contraction (EC)-coupling in ventricular myocytes and investigated whether these alterations are affected by the sex of the animal. Voltage-clamp experiments were conducted in myocytes from young adult (7 mo) and aged (24 mo) male and female mice. Intracellular Ca²⁺ concentrations and unloaded cell shortening were measured at 37°C with fura-2 and a video edge detector. Fractional shortening and Ca²⁺ current density were significantly reduced in aged male myocytes compared with those in young adult male cells. In addition, Ca²⁺ transients were significantly smaller in aged male myocytes. Sarcoplasmic reticulum (SR) content, assessed by rapid application of 10 mM caffeine, declined with age in male myocytes. However, EC coupling gain and fractional release of SR Ca²⁺ were similar in young adult and aged male cells. In contrast to results in male animals, fractional shortening and Ca²⁺ current densities were similar in young adult and aged myocytes isolated from female hearts. Furthermore, Ca²⁺ transient amplitudes were unaffected by age in female cells. Interestingly, SR Ca²⁺ content was elevated in aged female myocytes, and fractional SR Ca²⁺ release declined with age in females. However, the gain of EC coupling was not different in myocytes from young adult and aged female mice. These data demonstrate that age-related alterations in EC coupling are more prominent in myocytes from male hearts than in cells from female hearts and suggest that it is important to consider sex as a variable in studies of the effects of aging on cardiac EC coupling.

senescence; sex; sarcoplasmic reticulum; calcium transients; calcium-induced calcium release.

This article has been cited by other articles:

				R. H. Shutt and S. E. Howlett Hypothermia increases the gain of excitation-contraction coupling in guinea pig ventricular myocytes Am J Physiol Cell Physiol, September 1, 2008; 295(3): C692 - C700. [Abstract] [Full Text] [PDF]

				J. D. O'Brien, J. H. Ferguson, and S. E. Howlett Effects of ischemia and reperfusion on isolated ventricular myocytes from young adult and aged Fischer 344 rat hearts Am J Physiol Heart Circ Physiol, May 1, 2008; 294(5): H2174 - H2183. [Abstract] [Full Text] [PDF]

				J. R. Bell, E. R. Porrello, C. E. Huggins, S. B. Harrap, and L. M. D. Delbridge The intrinsic resistance of female hearts to an ischemic insult is abrogated in primary cardiac hypertrophy Am J Physiol Heart Circ Physiol, April 1, 2008; 294(4): H1514 - H1522. [Abstract] [Full Text] [PDF]

				J.-B. Shen, R. Shutt, A. Pappano, and B. T. Liang Characterization and mechanism of P2X receptor-mediated increase in cardiac myocyte contractility Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H3056 - H3062. [Abstract] [Full Text] [PDF]