Related Experiment Videos
Venous neuropeptide Y receptor responsiveness in patients with chronic heart failure
Q Feng1, M L Lambert, I D Callow
1Department of Medicine, London Health Sciences Centre, University of Western Ontario, Canada.
Background:
Chronic heart failure is associated with increased sympathetic nerve activity and elevated plasma neuropeptide Y levels. The aim of this study was to investigate whether increased neuropeptide Y release altered vascular neuropeptide Y responses in the dorsal hand veins in patients with chronic heart failure.
Methods And Results:
Neuropeptide Y responsiveness was studied in vivo with use of a hand vein tonometry technique in 14 patients with chronic heart failure and left ventricular ejection fraction (LVEF) values <20%, 16 patients with LVEF values from 20% to 35%, and 16 age-similar healthy control subjects. Plasma norepinephrine and neuropeptide Y levels were significantly elevated in patients with chronic heart failure and LVEF values <20% compared with control subjects (P < .01). Plasma neuropeptide Y but not norepinephrine levels were significantly elevated in patients with chronic heart failure and LVEF values from 20% to 35% compared with control subjects (P < .01). Increasing doses of neuropeptide Y (25 to 2,000 pmol/min) were infused into a dorsal hand vein of each subject. Dose-dependent venoconstriction to neuropeptide Y was observed in all subjects studied. The neuropeptide Y dose-response curve in patients with LVEF values from 20% to 35% was significantly shifted to the left compared with patients with LVEF values <20% and control subjects (P < .01), whereas no significant difference was observed between the control subjects and the patients with LVEF values <20%. No significant difference in neuropeptide Y dose responses was observed between patients with chronic heart failure with plasma neuropeptide Y levels above the median and patients with chronic heart failure with plasma neuropeptide Y levels below the median.
Conclusions:
In vivo venous neuropeptide Y receptor responsiveness is increased in patients with chronic heart failure and LVEF values from 20% to 35%. This increased neuropeptide Y responsiveness may contribute to venoconstriction at this stage of heart failure.