Dissociation of potentiation of Leu31 Pro34 neuropeptide Y on adrenergic and purinergic transmission in isolated canine splenic artery.
The present study observed the effects of an activation of neuropeptide Y (NPY) Y1 receptors on adrenergic and purinergic components of double-peaked vasoconstrictor responses to periarterial nerve stimulation in the isolated, perfused canine splenic arteries. The results showed that 3-30 nM Leu31 Pro34 neuropeptide Y (LP-NPY) produced a dose-dependent potentiation of double-peaked vasoconstrictor responses to trains of 30-s pulses at 1, 4 or 10 Hz of stimulation. The potentiation of LP-NPY of the nerve-stimulated vasoconstrictions were completely inhibited by subsequent blockade of alpha1-adrenoceptors or Y1 receptors with 0.1 microM prazosin or with 1 microM BIBP 3226 ((R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-argininami de), respectively. The remaining responses in the presence of LP-NPY and prazosin were abolished by P2X receptor desensitization with 1 microM alpha,beta-methylene ATP. Moreover, 30 nM LP-NPY failed to modify the vasoconstrictor responses to nerve stimulation after treatment with prazosin. A subsequent administration of alpha,beta-methylene ATP completely suppressed the remaining responses after prazosin and LP-NPY. The vasoconstrictions induced by 0.003-1 nmol noradrenaline and 0.003-1 micromol ATP were slightly, but not significantly enhanced by 30 nM LP-NPY. The observations indicated that activation of postjunctional NPY Y1 receptors may have an important role in the modulation of adrenergic rather than purinergic transmission of the sympathetic co-transmission.
Yang
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Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
Chiba
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D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009478:Neuropeptide Y / Q000031:analogs & derivatives* / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000378:metabolism*; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors; D011983:Receptors, Purinergic / Q000378:metabolism*; D013157:Splenic Artery / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
C092926:BIBP 3226; D009478:Neuropeptide Y; D011941:Receptors, Adrenergic; D017476:Receptors, Neuropeptide Y; D011983:Receptors, Purinergic; C062259:neuropeptide Y, Leu(31)-Pro(34)-; D000255:Adenosine Triphosphate; D001120:Arginine; D009638:Norepinephrine; D011224:Prazosin