PLASMA-IMMUNOREACTIVE NEUROPEPTIDE-Y IN CONGESTIVE-HEART-FAILURE AT REST AND DURING EXERCISE

The purpose of the study described here was to study plasma immunoreac tive Neuropeptide Y (NPY) at rest and during exercise in patients with congestive heart failure (CHF) and in healthy subjects. Thirty-five p atients, mean age 64 years, with CHF in optimal treatment and with a m ean ejection fraction of 32%, were studied at rest and during exercise . Twelve age and sex matched healthy subjects were compared for restin g values. Another nine healthy subjects were studied at rest and durin g exercise at a constant low load of 75 W and at a high load defined a s 80% of their individual maximal capacity. In patients with congestiv e heart failure mean plasma immunoreactive NPY at rest was 10.3 pmol l -1 and was not significantly different from the control group. No diff erences between patients with slight and severe CHF were found and the re was no correlation between plasma immunoreactive NPY and left ventr icular ejection fraction. Mean maximal exercise time was on average 6. 3 min. Only three patients exercised more than 10 min. At maximal exer cise mean plasma immunoreactive NPY was 10.6 pmol l-1 the same as at r est. Plasma noradrenaline was increased in CHF patients compared to he althy subjects, and rose further during exercise. In healthy subjects plasma immunoreactive NPY rose significantly on both workloads, but mo re on the high load (p < 0.05), when the rise was first significant af ter 10 min. Plasma immunoreactive NPY at rest and during exercise was not increased in CHF patients in optimal medical treatment. Consequent ly plasma immunoreactive NPY is not a useful marker of the severity of CHF in these patients. The lack of rise in plasma immunoreactive NPY during exercise in CHF patients may be due to the short exercise time in these patients.