Methods for the Detection of Altered -Adrenergic Receptor Signaling Pathways in Hypertrophied Hearts

β-Adrenergic receptor signaling, desensitization, and downregualtion are fundamental mechanisms that contribute to both normal and altered myocar dial function. The development of pharmacological and biochemical assays has provided the ability to measure alterations both in adrenergic receptor den sity and the subsequent coupling of adrenergic receptors downstream effec tors, namely, adenylyl cyclase. Furthermore, transthoracic echocardiography of the murine heart has provided insight into changes in cardiac physiology that accompany altered adrenergic receptor signaling. The protocols described within this chapter provide the means to quantify β-adrenergic density, mea sure adenylyl cyclase activity, and evaluate cardiac hypertrophy to better understand the mechanisms responsible for cardiac hypertrophy and heart failure.