Potentiation of beta-adrenergic signaling by adenoviral-mediated gene transfer in adult rabbit ventricular myocytes

Our laboratory has been testing the hypothesis that genetic modulation of the beta-adrenergic signaling cascade can enhance cardiac function. We have previously shown that transgenic mice with cardiac overexpression of either the human beta(2)-adrenergic receptor (beta(2)AR) or an inhibitor of the beta-adrenergic receptor kinase (beta ARK), an enzyme that phosphorylates and uncouples agonist-bound receptors, have increased myocardial inotropy. We now have created recombinant adenoviruses encoding either the beta(2)AR (Adeno-beta(2)AR) or a peptide beta ARK inhibitor (consisting of the carboxyl terminus of beta ARK1, Adeno-beta ARKct) and tested their ability to potentiate beta-adrenergic signaling in cultured adult rabbit ventricular myocytes. As assessed by radioligand binding. Adeno-beta(2)AR infection led to similar to 20-fold overexpression of beta-adrenergic receptors. Protein immunoblots demonstrated the presence of the Adeno-beta ARKct transgene. Both transgenes significantly increased isoproterenoIstimulated cAMP as compared to myocytes infected with an adenovirus encoding beta-galactosidase (Adeno-beta Gal) but did not affect the sarcolemmal adenylyl cyclase response to Forskolin or NaF. beta-Adrenergic agonist-induced desensitization was significantly inhibited in Adeno-beta ARKct-infected myocytes (16+/-2%) as compared to Adeno-beta Gal-infected myocytes (37+/-1%, P < 0.001). We conclude that recombinant adenoviral gene transfer of the beta(2)AR or an inhibitor of beta ARK-mediated desensitization can potentiate beta-adrenergic signaling.