PLASMA BETA-ENDORPHIN RESPONSE TO EXERCISE IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Objective: To determine whether the net release of beta-endorphin duri ng exercise, similar to that of norepinephrine, is related to function al disability in patients with congestive heart failure, Background: P lasma beta-endorphin and norepinephrine levels are elevated at rest in patients with heart failure, reflecting a functional disability. The net release of beta-endorphin during exercise in patients with heart f ailure is unknown, Methods: We measured plasma beta-endorphin and nore pinephrine levels (respectively: radioimmune and radioenzymatic assay) at rest and during graded exercise testing in 28 patients with conges tive heart failure (Weber's class A, 10; B, 9; and C, 9) and in 9 norm al subjects, Results: At rest, plasma beta-endorphin levels were highe r in patients in classes B and C than in normal subjects (p<0.05 and < 0.01, respectively). At peak exercise, patients in different functiona l classes and normal subjects reached similar beta-endorphin levels. H owever, the net release of beta-endorphin during exercise was lower in patients in classes B and C than in those in class A and normal subje cts (p<0.01 for both), At rest, plasma norepinephrine levels were sign ificantly higher in patients than in normal subjects (p<0.01). At peak exercise, norepinephrine levels were significantly lower in class C p atients than in normal subjects (p<0.05), and tended to be lower in pa tients in classes A and B (p=NS); The net release of norepinephrine du ring exercise was lower in patients than in normal subjects (p<0.01). In patients, releases of both beta-endorphin and norepinephrine during exercise were related to peak oxygen consumption and duration of exer cise, but not to resting left ventricular ejection fraction, Conclusio ns: In patients with congestive heart failure, the net release of plas ma beta-endorphin during exercise is decreased, like norepinephrine, a nd reflects a functional disability.