Cardiac Sympathetic Nerve Function in Congestive Heart Failure

Abstract

Background Increased availability of norepinephrine (NE) for activation of cardiac adrenoceptors (increased cardiac adrenergic drive) and depletion of myocardial NE stores may contribute to the pathophysiology and progression of congestive heart failure. This study used a comprehensive neurochemical approach to examine the mechanisms responsible for these abnormalities. Methods and Results Subjects with and without congestive heart failure received intravenous infusions of [3H]NE. Cardiac spillover, reuptake, vesicular-axoplasmic exchange, and tissue stores of NE were assessed from arterial and coronary venous plasma concentrations of endogenous and [3H]-labeled NE and dihydroxyphenylglycol. Tyrosine hydroxylase activity was assessed from plasma dopa, and NE turnover was assessed from measurements of NE metabolites. NE release and reuptake were both increased in the failing heart; however, the efficiency of NE reuptake was reduced such that cardiac spillover of NE was increased disproportionately more tha...