Gender differences in the modulation of cardiac gene expression by dietary conjugated linoleic acid isomersThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute

• Published in: Canadian journal of physiology and pharmacology 2007-03, Vol.85 (3-4), p.465-475
• Main Authors: Tappia, Paramjit S, Dent, Melissa R, Aroutiounova, Nina, Babick, Andrea P, Weiler, Hope
• Format: Article
• Language: English
• Subjects: capture du Ca; conjugated linoleic acid isomers; différences selon le sexe; expression génique; gender differences; gene expression; isomères de l'acide linoléique conjugué; libération du Ca; release; réticulum sarcoplasmique; sarcolemma; sarcolemme; sarcoplasmic reticulum; uptake
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/Y06-104

In an earlier study, we showed that dietary conjugated linoleic acid (CLA) isomers can exert differential effects on heart function in male and female rats, but the underlying mechanisms for these actions are not known. Cardiomyocyte Ca 2+ cycling is a key event in normal cardiac contractile function and defects in Ca 2+ cycling are associated with cardiac dysfunction and heart disease. We therefore hypothesized that abnormalities in the sarcolemmal (SL) and sarcoplasmic reticulum (SR)-mediated regulation of intracellular Ca 2+ contribute to altered cardiac contractile function of male and female rats owing to dietary CLA isomers. Healthy male and female Sprague-Dawley rats were fed different CLA isomers, (cis-9, trans-11 (c9,t11) and trans-10, cis-12 (t10,c12)) individually and in combination (50:50 mix as triglyceride or fatty acids) from 4 to 20 weeks of age. We determined the mRNA levels of sarcoplasmic/endoplasmic reticulum Ca 2+ -ATPase (SERCA) 2a, ryanodine receptor, phospholamban, calsequestrin, Na + -Ca 2+ -exchanger (NCX), and L-type Ca 2+ channel in the left ventricle (LV) by RT-PCR. The SR function was assessed by measurement of Ca 2+ -uptake and -release. Significant gender differences were seen in the LV NCX, L-type Ca 2+ channel, and ryanodine receptor mRNA expression levels in control male and female rats. Dietary CLA isomers in the various forms induced changes in the mRNA levels of SERCA 2a, NCX, and L-type Ca 2+ channel in the LV of both male and female hearts. Whereas protein contents of the Ca 2+ cycling proteins were altered, changes in SR Ca 2+ -uptake and -release were also detected in both male and female rats in response to dietary CLA. The results of this study demonstrate that long-term dietary supplementation can modulate cardiac gene expression and SR function in a gender-related manner and may, in part, contribute to altered cardiac contractility.