Modulation by neuropeptide Y of parasympathetic nerve-evoked nasal vasodilatation via Y2 prejunctional receptor.
1. In pentobarbitone anaesthetized dogs, preganglionic stimulation of the superior cervical sympathetic nerve (15V, 1 ms, 10 Hz) induced marked reduction of nasal arterial blood flow, whereas parasympathetic nerve stimulation (5 V, 1 ms, 10-30 Hz) evoked frequency-dependent vasodilatation. 2. Sympathetic nerve stimulation for 3 min at 10 Hz evoked significant (P < 0.05) and prolonged attenuation of the vasodilator response to subsequent parasympathetic stimulation. Pretreatment with phentolamine (0.5 mg kg-1 h-1), propranolol (1 mg kg-1) and atropine (0.5 mg kg-1) reduced the vasoconstrictor effect of sympathetic stimulation by 35 +/- 4% whereas the parasympathetic nerve-evoked vasodilatation was not significantly modified. Atropine-resistant parasympathetic vasodilatation remained significantly attenuated for more than 30 min after non-adrenergic sympathetic nerve-evoked vasoconstriction. 3. Vasodilator effects of exogenous vasoactive intestinal polypeptide and peptide histidine isoleucine and vasoconstrictor effects of exogenous neuropeptide Y (NPY) and the NPY analogue [Leu31, Pro34] NPY (Y1-receptor agonist, 8 nmol kg-1), were not altered by adrenoceptor antagonists and atropine f1p4eas the effects of exogenous noradrenaline and acetylcholine were virtually abolished. Attenuation of parasympathetic-evoked vasodilatation could be mimicked by exogenous NPY (8 nmol kg-1) and the NPY analogue, N-acetyl [Leu28, Leu31] NPY 24-36 (Y2-receptor agonist, 20 nmol kg-1) but not by exogenous Y1-receptor agonist. The Y2-receptor agonist did not show significant vasoconstrictor action. 4. It is concluded that sympathetic nerve stimulation attenuates parasympathetic vasodilatation via NPY release acting on prejunctional Y2 receptors.
Lacroix
J S
JS
Prince of Wales Medical Research Institute, Prince of Wales Hospital, Randwick, Sydney, NSW, Australia.
Ulman
L G
LG
Potter
E K
EK
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology; D008297:Male; D008438:Maxillary Artery / Q000187:drug effects / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects; D009478:Neuropeptide Y / Q000031:analogs & derivatives / Q000494:pharmacology*; D009666:Nose / Q000098:blood supply*; D010275:Parasympathetic Nervous System / Q000187:drug effects*; D010276:Parasympatholytics / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D017476:Receptors, Neuropeptide Y / Q000187:drug effects*; D012039:Regional Blood Flow / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects*
D009478:Neuropeptide Y; D010276:Parasympatholytics; D010446:Peptide Fragments; D017476:Receptors, Neuropeptide Y; C084653:neuropeptide Y (24-36), Ac-(Leu(28,31))-; C062259:neuropeptide Y, Leu(31)-Pro(34)-