Regulatory peptides in the plasma of patients with chronic cardiac failure at rest and during exercise.

The levels of several regulatory peptides were measured in peripheral plasma samples from individuals with chronic cardiac failure (CCF) and matched controls in both the resting state and during a short period of maximal exercise. Basal levels of noradrenaline (NA; 705 +/- 114 vs 195 +/- 54 ng.l-1; mean +/- SEM; P < 0.05), plasma renin activity (PRA; 12.9 +/- 2.9 vs 2.1 +/- 0.3 ng AI ml-1.h-1; P < 0.05) and aldosterone (ALDO; 325 +/- 49 vs 87 +/- 8 ng.l-1; P < 0.05) were all raised in the patients with CCF, and increased further with exercise. Basal circulating levels of atrial natriuretic peptide (ANP) were also significantly higher in the CCF group compared to controls (136 +/- 35 vs 27 +/- 5 ng.l-1; P < 0.01), but the response to exercise was attenuated, so that at peak exercise, no significant difference was observed. Basal circulating levels of gastrin-releasing peptide (GRP) (29 +/- 4 vs 40 +/- 4 ng.l-1; P < 0.05) and secretin (13 +/- 1 vs 32 +/- 4 ng.l-1; P < 0.05) were significantly lower in the CCF group when compared to controls and there was no significant change in the levels of either peptide with exercise. Levels of neurokinin A (NKA), neuropeptide Y (NPY) and neurotensin (NT) were somewhat higher in patients, but the differences were not significant, and there were no changes during exercise. There were also no significant differences in the levels of vasoactive intestinal peptide (VIP), glucose-dependent insulinotropic polypeptide (GIP), insulin or glucagon in either experimental group both before and during exercise. We have therefore identified different circulating levels of certain regulatory peptides in patients with CCF, but the significance of these remains unclear.