Abstract:
Background—Genetic manipulation to reverse molecular abnormalities associated with dysfunctional myocardium may provide novel treatment. This study aimed to determine the feasibility and functional consequences of in vivo β-adrenergic receptor kinase (βARK1) inhibition in a model of chronic left ventricular (LV) dysfunction after myocardial infarction (MI).
Methods and Results—Rabbits underwent ligation of the left circumflex (LCx) marginal artery and implantation of sonomicrometric crystals. Baseline cardiac physiology was studied 3 weeks after MI; 5×1011 viral particles of adenovirus was percutaneously delivered through the LCx. Animals received transgenes encoding a peptide inhibitor of βARK1 (Adeno-βARKct) or an empty virus (EV) as control. One week after gene delivery, global LV and regional systolic function were measured again to assess gene treatment. Adeno-βARKct delivery to the failing heart through the LCx resulted in chamber-specific expression of the βARKct. Baseline in vivo LV systolic performance was improved in Adeno-βARKct–treated animals compared with their individual pre–gene delivery values and compared with EV-treated rabbits. Total β-AR density and βARK1 levels were unchanged between treatment groups; however, β-AR–stimulated adenylyl cyclase activity in the LV was significantly higher in Adeno-βARKct–treated rabbits compared with EV-treated animals.
Conclusions—In vivo delivery of Adeno-βARKct is feasible in the infarcted/failing heart by coronary catheterization; expression of βARKct results in marked reversal of ventricular dysfunction. Thus, inhibition of βARK1 provides a novel treatment strategy for improving the cardiac performance of the post-MI heart.
