Acute effects of β-endorphin on cardiovascular function in patients with mild to moderate chronic heart failure

Background Cardiomyocytes produce opioid peptides and receptors. β-Endorphin is increased in the plasma of patients with congestive heart failure (CHF). We evaluated whether an intravenous infusion of β-endorphin exerted any effect on cardiovascular function and on the neurohormonal milieu in patients with mild to moderate CHF. Methods According to a double-blind, placebo-controlled design, 10 patients (5 men, age 46.9 ± 8.2 years [mean ± SD]) with CHF and New York Heart Association functional class II to III received, in random order, 1-hour intravenous infusion of β-endorphin (500 μg/h) and, on a separate occasion, received placebo and underwent echocardiographic and laboratory measurements at baseline and during infusions. Results β-Endorphin significantly increased left ventricular ejection fraction (LVEF) (P = .0001) and stroke volume (P = .0001), and reduced systemic vascular resistance (P = .031) in patients with CHF. These changes were paralleled by a significant increase in plasma levels of glucagon (P = .0001), GH (P = .0001), and IGF-1 (P = .0001), and a significant decrease in plasma levels of endothelin (P = .0001) and catecholamines (P = .01). No hemodynamic and neurohormonal changes were observed during the placebo study in any patient. Conclusions We conclude that a short-term, high dose infusion of β-endorphin improves LVEF, reduces systemic vascular resistance, blunts the neurohormonal activation, and stimulates the GH/IGF-1 axis in patients with mild to moderate CHF.