FIGURE 1. Effect of chronic infusion of NE on myocardial noradrenergic neurotransmission. After 5-d NE infusion, similar reduction in NE uptake, uptake-1 carrier density, ß-adrenergic receptor (BAR) density, and responsiveness to agonists was observed in left ventricle of rats. ACA = adenylyl cyclase activity; B_max = carrier or receptor protein density. *P < 0.05. **P < 0.01. ***P < 0.001.