Neuropeptide Y and sympathetic vascular control in man.
A parallel increase in systemic plasma levels of neuropeptide Y (NPY)-like immunoreactivity (LI) and noradrenaline (NA) was found during thoracotomy and surgery involving cardiopulmonary bypass in man. Thus, plasma levels of NPY-LI increased from 29 +/- 4 pmol/l before anaesthesia to 59 +/- 10 after thoracotomy and to 87 +/- 8 pmol/l upon cardiopulmonary bypass. The corresponding NA levels increased from 1.3 +/- 0.1 nmol/l before anaesthesia to 3.0 +/- 0.6 and 4.2 +/- 5 nmol/l after thoracotomy and cardiopulmonary bypass, respectively. A significant correlation was found between plasma levels of NPY-LI and NA during the operation but not between NPY-LI and adrenaline. The NPY-LI in human plasma was found to be similar to synthetic porcine NPY on reversed phase high performance liquid chromatography. Human submandibular arteries contained high levels of NPY-LI (24 +/- 3 pmol/g). In in vitro experiments on isolated human submandibular arteries, NPY in low concentrations (1000 pmol/l) was found to potentiate the contractile effects of NA or transmural nerve stimulation and to exert vasoconstrictor activity per se in higher concentrations. The calcium-entry antagonist nifedipine abolished both the NPY-induced contractions and the enhancement of NA-evoked contractions. NPY depressed the nerve stimulation-evoked 3H-NA release from human submandibular arteries via a prejunctional mechanism which was resistant to nifedipine. NPY contracted human mesenteric veins and renal arteries, but not mesenteric arteries. In conclusion, NPY seems to be co-released with NA upon sympathetic activation in man. Furthermore, NPY exerts both pre- and postjunctional effects on sympathetic control of human blood vessels.
D000328:Adult; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D001794:Blood Pressure; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D002851:Chromatography, High Pressure Liquid; D004558:Electric Stimulation; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000601:surgery; D009419:Nerve Tissue Proteins / Q000097:blood* / Q000494:pharmacology; D009478:Neuropeptide Y; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood*; D010525:Peripheral Nerves / Q000502:physiology; D013552:Swine; D013903:Thoracic Surgery; D014655:Vascular Resistance
D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D009543:Nifedipine; D009638:Norepinephrine