Molecular basis of ventricular arrhythmogenicity in a Pgc-1α deficient murine model

Mitochondrial dysfunction underlying metabolic disorders such as obesity and diabetes mellitus is strongly associated with cardiac arrhythmias. Murine Pgc-1 alpha(& minus;/& minus;)& nbsp;hearts replicate disrupted mitochondrial function and model the associated pro-arrhythmic electrophysiological abnormalities. Quantitative PCR, western blotting and histological analysis were used to investigate the molecular basis of the electrophysiological changes associated with mitochondrial dysfunction. qPCR analysis implicated downregulation of genes related to Na+-K+& nbsp;ATPase activity (Atp1b1), surface Ca2+& nbsp;entry (Cacna1c), action potential & nbsp;repolarisation & nbsp;(Kcnn1), autonomic function (Adra1d, Adcy4, Pde4d, Prkar2a), and morphological properties (Myh6, Tbx3) in murine Pgc-1 alpha(& minus;/& minus;)& nbsp;ventricles. Western blotting revealed reduced Na(V)1.5 but normal Cx43 expression. Histological analysis revealed increased tissue fibrosis in the Pgc-1 alpha(& minus;/& minus;)& nbsp;ventricles. These present findings identify altered transcription amongst a strategically selected set of genes established as encoding proteins involved in cardiac electrophysiological activation and therefore potentially involved in alterations in ventricular activation and Ca2+& nbsp;homeostasis & nbsp;in arrhythmic substrate associated with Pgc-1 alpha deficiency. They complement and complete previous studies examining such expression characteristics in the atria and ventricles of Pgc-1 deficient murine hearts.

Automated summary

Mitochondrial dysfunction linked to metabolic disorders like obesity and diabetes is strongly associated with cardiac arrhythmias, as shown in a murine Pgc-1 alpha(-/-) model. Molecular analysis revealed downregulation of genes related to various cardiac functions in the ventricles, along with increased tissue fibrosis. These findings suggest altered transcription of key genes involved in cardiac electrophysiological activation in arrhythmic substrate associated with Pgc-1 alpha deficiency.