Eastern Kentucky University

Sex-specific Differences in Gene Expression of Hypertrophy Markers in Primary Neonatal Cardiomyocyte Cultures

Institution

Eastern Kentucky University

Abstract

It is well established that premenopausal women develop cardiovascular disease (CVD) at a lower rate than men. Postmenopausal rates of CVD increase and, in some studies, surpass that of their age matched male counterparts, suggesting that estrogen may be an important cardioprotective agent. It is not understood how estrogen and other female-specific factors prevent the development of CVD, including cardiac hypertrophy (enlargement of the heart), and heart failure. Our goal is to assess sex-specific gene expression changes that occur during cardiac hypertrophy, particularly cardiomyocyte hypertrophy (enlargement of individual heart cells), in the presence or absence of estradiol (E2) using a primary neonatal rat cardiomyocyte culture system. Sex specific cardiomyocyte cultures were established and treated with phenylephrine (PE) to induce hypertrophy in the presence or absence of E2. After 24 hours of incubation, RNA was extracted from the cells and converted into cDNA for Real-Time PCR analysis to determine gene expression levels. Known hypertrophy markers: BNP (brain natriuretic peptide), ANP (atrial natriuretic peptide), and MHC-beta assays were used to test for hypertrophy in all samples. Interestingly, male and female cultures expressed hypertrophy markers at different levels, regardless of hypertrophy. Observations of the sex-specific cardiomyocyte cultures suggest that the male cells are proliferating faster than the female cells. We performed cell cycle analysis utilizing BrdU in ELISA, and flow cytometry to establish proliferation rates for male cardiomyocytes vs female cardiomyocytes. Variations in proliferation rates between male and female cardiomyocytes may also be a key to understanding male/female differences in the development of CVD.

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Sex-specific Differences in Gene Expression of Hypertrophy Markers in Primary Neonatal Cardiomyocyte Cultures

It is well established that premenopausal women develop cardiovascular disease (CVD) at a lower rate than men. Postmenopausal rates of CVD increase and, in some studies, surpass that of their age matched male counterparts, suggesting that estrogen may be an important cardioprotective agent. It is not understood how estrogen and other female-specific factors prevent the development of CVD, including cardiac hypertrophy (enlargement of the heart), and heart failure. Our goal is to assess sex-specific gene expression changes that occur during cardiac hypertrophy, particularly cardiomyocyte hypertrophy (enlargement of individual heart cells), in the presence or absence of estradiol (E2) using a primary neonatal rat cardiomyocyte culture system. Sex specific cardiomyocyte cultures were established and treated with phenylephrine (PE) to induce hypertrophy in the presence or absence of E2. After 24 hours of incubation, RNA was extracted from the cells and converted into cDNA for Real-Time PCR analysis to determine gene expression levels. Known hypertrophy markers: BNP (brain natriuretic peptide), ANP (atrial natriuretic peptide), and MHC-beta assays were used to test for hypertrophy in all samples. Interestingly, male and female cultures expressed hypertrophy markers at different levels, regardless of hypertrophy. Observations of the sex-specific cardiomyocyte cultures suggest that the male cells are proliferating faster than the female cells. We performed cell cycle analysis utilizing BrdU in ELISA, and flow cytometry to establish proliferation rates for male cardiomyocytes vs female cardiomyocytes. Variations in proliferation rates between male and female cardiomyocytes may also be a key to understanding male/female differences in the development of CVD.