title: Vasoconstriction in exercising skeletal muscles: a potential role for neuropeptide Y?
abstract: There is evidence that neuropeptide Y (NPY) acts as a neurotransmitter in vascular smooth muscle and is released with norepinephrine from sympathetic nerves. We hypothesized that NPY Y(1) receptor stimulation would produce vasoconstriction in resting and exercising skeletal muscle. Nine mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and a catheter in one femoral artery. The selective NPY Y(1) receptor agonist [Leu(31),Pro(34)]NPY was infused as a bolus into the femoral artery catheter at rest and during mild, moderate, and heavy exercise. Intra-arterial infusions of [Leu(31),Pro(34)]NPY elicited reductions (P < 0.05) in vascular conductance of 38 +/- 3, 25 +/- 2, 17 +/- 1, and 11 +/- 1% at rest, 3 miles/h, 6 miles/h, and 6 miles/h and 10% grade, respectively. The agonist infusions did not affect (P > 0.05) blood flow in the contralateral iliac artery. To examine whether nitric oxide (NO) is responsible for the attenuated vasoconstrictor response during exercise to NPY Y(1) receptor stimulation, the infusions were repeated after NO synthase blockade. These infusions yielded reductions (P < 0.05) in vascular conductance of 47 +/- 3, 23 +/- 2, 19 +/- 3, and 12 +/- 2% at rest, 3 miles/h, 6 miles/h, and 6 miles/h and 10% grade, respectively. NPY Y(1) receptor responsiveness was attenuated (P < 0.05) during exercise compared with rest. Blockade of NO production did not affect (P > 0.05) the attenuation of NPY Y(1) receptor responsiveness during exercise. These data support the hypothesis that NPY Y(1) receptors can produce vasoconstriction in exercising skeletal muscle.
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53295, USA. jbuckwal@mcw.edu
authors.forename: John B
authors.initials: JB
authors.lastname: Buckwalter
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Hamann
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Kluess
authors.forename: Philip S
authors.initials: PS
authors.lastname: Clifford
mesh_terms: D000818:Animals; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009478:Neuropeptide Y / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D017476:Receptors, Neuropeptide Y / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y; C097212:neuropeptide Y-Y1 receptor; C062259:neuropeptide Y, Leu(31)-Pro(34)-; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester