ADRB2 and cardiomyopathy: Acute β-AR stimulation leads to increased LTCC activity like that observed in human heart failure (Tsien et al. 1986; Yue et al. 1990; Schröder et al. 1998), and increased LTCC activity can lead to cardiomyopathy and heart failure in mice (Nakayama et al. 2007; Beetz et al. 2009).