Endogenous opioid peptides and mental stress in congestive heart failure patients.

Two groups of patients with acute congestive heart failure (CHF), New York Heart Association class III, presenting elevated plasma values of beta-endorphin, norepinephrine, atrial natriuretic factor (ANF) and endothelin-1, underwent the Mental Arithmetic Test (MAT) during placebo (n = 10) and naloxone hydrochloride (n = 10) infusion. The MAT during placebo significantly (p < 0.01) increased blood pressure, heart rate, plasma levels of Met-enkephalin, dynorphin B, beta-endorphin, norepinephrine, ANF and endothelin-1. The increases in norepinephrine, ANF and hemodynamics after the MAT during naloxone infusion were higher (p < 0.01) than those during placebo; thus, the transient upregulation of the endogenous opioid system during stress in CHF patients attenuates the hemodynamic response by reducing norepinephrine release.