July 1, 1997Journal of Biological Chemistry262 citationsOpen Access
Mechanism of β-Adrenergic Receptor Desensitization in Cardiac Hypertrophy Is Increased β-Adrenergic Receptor Kinase
Structured PICO
Does betaARK mediate beta-adrenergic receptor desensitization in pressure overload cardiac hypertrophy in mice?
P
Population
Mouse models of cardiac hypertrophy (pressure overload via transverse aortic constriction or oncogenic ras overexpression) and transgenic mice overexpressing a betaARK inhibitor.
I
Intervention
Transverse aortic constriction (TAC) for 7 days; overexpression of a betaARK inhibitor.
C
Comparator
Control mice.
O
Outcome
Beta-adrenergic receptor desensitization (inotropic response to dobutamine) and G protein-coupled receptor kinase (GRK/betaARK) activity.surrogate
BetaARK is a central molecule involved in beta-adrenergic receptor desensitization during pressure overload cardiac hypertrophy, driven by neurohumoral activation rather than cellular hypertrophy itself.
Abstract
Pressure overload cardiac hypertrophy in the mouse was achieved following 7 days of transverse aortic constriction. This was associated with marked beta-adrenergic receptor (beta-AR) desensitization in vivo, as determined by a blunted inotropic response to dobutamine. Extracts from hypertrophied hearts had approximately 3-fold increase in cytosolic and membrane G protein-coupled receptor kinase (GRK) activity. Incubation with specific monoclonal antibodies to inhibit different GRK subtypes showed that the increase in activity could be attributed predominately to the beta-adrenergic receptor kinase (betaARK). Although overexpression of a betaARK inhibitor in hearts of transgenic mice did not alter the development of cardiac hypertrophy, the beta-AR desensitization associated with pressure overload hypertrophy was prevented. To determine whether the induction of betaARK occurred because of a generalized response to cellular hypertrophy, betaARK activity was measured in transgenic mice homozygous for oncogenic ras overexpression in the heart. Despite marked cardiac hypertrophy, no difference in betaARK activity was found in these mice overexpressing oncogenic ras compared with controls. Taken together, these data suggest that betaARK is a central molecule involved in alterations of beta-AR signaling in pressure overload hypertrophy. The mechanism for the increase in betaARK activity appears not to be related to the induction of cellular hypertrophy but to possibly be related to neurohumoral activation.