Y1R control of sciatic nerve blood flow in the Wistar Kyoto rat.
We hypothesized that neuropeptide Y (NPY) exerts vasoconstrictor properties in sciatic nerve blood supply by a Y1 receptor (Y1R) mechanism. Using Doppler ultrasound (40MHz), we measured blood flow velocity through a sciatic nerve supply artery during infusions of NPY and/or Y1R blockade with BIBP3226 in Wistar Kyoto rats before, and following, ganglionic blockade with Hexamethonium (Hex). Following Hex infusion, mean arterial pressure (baseline: 83±18, Hex: 57±3 mm Hg) was reduced. After 30 min, the index of conductance at the sciatic nerve (velocity/MAP expressed as % baseline) started to increase from 103±35 to 127±39% baseline in the following 30 min (p<0.05). Infusion of NPY (Y1 agonist) minimized this dilatory response (Hex baseline: 99±15, NPY: 104±11% baseline; NS). This NPY-induced attenuation was, in turn, minimized by BIBP3226 (Hex baseline: 73±12, NPY+BIBP3226: 89±14% baseline). Neither NPY nor BIBP3226 infusions without Hex affected the sciatic nerve arterial conductance. We conclude that the late dilation following Hex which is reversed by Y1R activation suggests some level of sympathetic control over sciatic nerve blood flow.
School of Kinesiology, The University of Western Ontario, London, Ontario, Canada, N6A 3K7.
Jasna
J
Twynstra
Philip J
PJ
Medeiros
James C
JC
Lacefield
Dwayne N
DN
Jackson
J Kevin
JK
Shoemaker
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001158:Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012039:Regional Blood Flow; D012584:Sciatic Nerve / Q000098:blood supply* / Q000378:metabolism; D015398:Signal Transduction; D018617:Ultrasonography, Doppler, Pulsed; D014664:Vasodilation / Q000187:drug effects
C092926:BIBP 3226; D005730:Ganglionic Blockers; D009478:Neuropeptide Y; C066211:Npy1r protein, rat; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D018738:Hexamethonium; D001120:Arginine