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Changes of creatine kinase gene expression in rat heart post-myocardial infarction
1Department of Medicine, Universität Würzburg, Germany.
Insights
Heart failure alters creatine kinase (CK) gene expression, increasing fetal BB-CK and decreasing M-CK mRNA. These changes in cardiac energy metabolism correlate with heart failure severity.
Area of Science:
- Biochemistry
- Cardiology
- Molecular Biology
Background:
- Creatine kinase (CK) is vital for cardiac energy.
- Heart failure leads to changes in CK isoenzyme activity, mimicking a fetal pattern.
- Myocardial CK gene expression changes are not fully understood in heart failure.
Purpose of the Study:
- To investigate myocardial expression of B-, M-, and sarcomeric mito-CK genes in a rat model of heart failure post-myocardial infarction (MI).
Main Methods:
- Rats underwent MI or sham surgery; myocardium was harvested after 2 months.
- CK activity and isoenzyme distribution were measured.
- Quantitative PCR assessed B-, M-, and mito-CK mRNA levels, normalized to GAPDH.
Main Results:
- Total CK activity showed a trend towards reduction post-MI.
- CK isoenzyme distribution revealed increased BB-+MB-CK and decreased mito-CK.
- Relative B-CK mRNA levels significantly increased, while M-CK mRNA levels significantly decreased post-MI.
- B-CK and M-CK mRNA changes correlated with left-ventricular end-diastolic pressure (LVEDP).
- Mito-CK mRNA levels remained unchanged.
Conclusions:
- Post-MI rat myocardium exhibits increased B-CK mRNA and reduced M-CK mRNA expression.
- These gene expression changes reflect altered cardiac energy metabolism in heart failure.
- CK gene expression alterations are linked to hemodynamic changes in heart failure.
Abstract:
Creatine kinase (CK) plays a crucial role in cardiac energy transduction. During chronic cardiac stress conditions leading to hypertrophy and/or heart failure, the profile of CK isoenzyme activities changes towards a fetal pattern with increases of BB- and MB-CK and decreases of MM-CK and mito-CK. Changes of myocardial CK gene expression are only indirectly reflected by measurements of CK activities. The purpose of this work was, therefore, to determine myocardial expression of B-, M- and sarcomeric mito-CK genes in an animal model of heart failure where hemodynamic alterations and CK system changes are well defined, that is, in the rat heart post-myocardial infarction. Intact residual left ventricular myocardium was harvested 2 months following infarction (MI; n = 7) or sham operation (sham; n = 6) after in vivo left-ventricular end-diastolic pressure (LVEDP) was recorded. Total CK activity was measured spectrophotometrically, CK isoenzyme distribution with agarose gel electrophoresis. Steady state mRNA levels coding for B-, M- and mito-CK genes were measured with quantitative PCR and were normalized for GAPDH expression. Total CK activity tended to be reduced in MI (5.51 +/- 0.62 IU/mg protein) compared to sham (6.77 +/- 0.24; P = 0.55). CK isoenzyme distribution showed an increase of fetal BB- + MB-CK (MI 22.0 +/- 3.1%, sham 15.1 +/- 1.0%; P < 0.05), no change of MM-CK and a decrease of mito-CK (27.0 +/- 1.5% sham, 20.8 +/- 2.0% MI: P < 0.05). Relative B-CK mRNA levels increased (sham 0.46 +/- 0.06, MI 1.03 +/- 0.09; P < 0.05) and M-CK mRNA levels decreased (sham 1.06 +/- 0.08. MI 0.66 +/- 0.09; P < 0.05) significantly post-MI. The increase of B-CK mRNA (r = 0.72; P = 0.009) and the decrease of M-CK mRNA (r = 0.76; P = 0.003) correlated significantly with in vivo LVEDP. Mito-CK mRNA levels remained unchanged after MI (sham 0.94 +/- 0.16, MI 0.98 +/- 0.09). Intact residual left-ventricular myocardium post-MI is characterized by increased B-CK-mRNA and reduced M-CK-mRNA expression.