NEUROPEPTIDE-Y Y-1 RECEPTOR BLOCKADE DOES NOT ALTER ADRENERGIC-NERVE RESPONSES OF THE RAT TAIL ARTERY

Using the selective neuropeptide Y Y-1 receptor antagonist, BIBP3226 - 2-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-D- argininamide], the r ole of endogenous neuropeptide Y in mediating vasoconstrictor response s to adrenergic nerve stimulation was investigated by recording isomet ric force from isolated rat tail artery segments. BLBP3226 had no effe ct on contractile responses to adrenergic nerve stimulation (10 pulses ; 0.5-2 Hz), but it completely blocked the enhancement of contraction produced by exogenous neuropeptide Y. When frequency and train length of the transmural nerve stimulation were increased (100 pulses; 1-16 H z), contractile responses were still unaffected by BIBP3226. A peptida se inhibitor mixture known to increase responses to exogenous neuropep tide Y was added; however, BLBP3226 still did not influence contractil e responses to adrenergic nerve stimulation. Thus, contractile respons es to adrenergic nerve stimulation in the rat tail artery do not appea r to involve the release and postjunctional action of endogenous neuro peptide Y; however, exogenous neuropeptide Y does potentiate these res ponses by acting on Y-1 receptors. (C) 1997 Elsevier Science B.V.