MYOCARDIAL EXPRESSION OF A CONSTITUTIVELY ACTIVE ALPHA(1B)-ADRENERGICRECEPTOR IN TRANSGENIC MICE INDUCES CARDIAC-HYPERTROPHY

Transgenic mice were generated by using the alpha-myosin heavy chain p romoter coupled to the coding sequence of a constitutively active muta nt alpha(1B)-adrenergic receptor (AR). These transgenic animals demons trated cardiac-specific expression of this alpha(1)-AR with resultant activation of phospholipase C as shown by increased myocardial diacylg lycerol content. A phenotype consistent with cardiac hypertrophy devel oped in adult transgenic mice with increased heart/body weight ratios, myocyte cross-sectional areas, and ventricular atrial natriuretic fac tor mRNA levels relative to nontransgenic controls. These transgenic a nimals may provide insight into the biochemical triggers that induce h ypertrophy in cardiac disease and serve as a convenient experimental m odel for studies of this condition.