BACKGROUND

We tested the hypothesis that increased cardiac myocyte adenylyl cyclase (AC) content increases cardiac function and response to catecholamines in cardiomyopathy.

METHODS AND RESULTS

Transgenic mice with cardiac-directed expression of AC type VI (ACVI) were crossbred with mice with cardiomyopathy induced by cardiac-directed Gq expression. Gq mice had dilated left ventricles, reduced heart function, decreased cardiac responsiveness to catecholamine stimulation, and impaired beta-adrenergic receptor (betaAR)-dependent and AC-dependent cAMP production. Gq/AC mice showed improved basal cardiac function in vivo (P=0.01) and ex vivo (P<0.0005). When stimulated through the betaAR, cardiac responsiveness was increased (P=0.02), and cardiac myocytes showed increased cAMP production in response to isoproterenol (P=0.03) and forskolin (P<0.0001).

CONCLUSIONS

Increasing myocardial ACVI content in cardiomyopathy restores cAMP-generating capacity and improves cardiac function and responsiveness to betaAR stimulation.