Evidence for a novel vasospastic transmitter system, neuromedin U, in the equine digital circulation.
The brain-gut peptide neuromedin U (NMU) is a ligand for the G-protein-coupled receptors, NMU1 and NMU2. In humans, an extended form of this peptide, NMU-25, and the structurally related peptide, neuromedin S (NMS), both produce potent vasoconstriction in isolated blood vessels. The aim of this study was to determine whether NMU fulfilled criteria for controlling vasoreactivity in the equine digital circulation. NMU receptors were characterised in the equine digital artery and vein based on the pharmacological criteria of specific, saturable and high affinity binding. Immunoreactive peptide was detected in the equine digital artery and vein using anti-NMS antisera. [(125)I]-NMU-25 binding sites were localised to the smooth muscle layer and NMU-25 potently constricted the digital vein. This provides evidence for NMU as a transmitter in the equine digital circulation.
Mitchell
John D
JD
Clinical Pharmacology Unit, University of Cambridge, Level 6 Centre for Clinical Investigation, Box 110 Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. apd10@medschl.cam.ac.uk
Kuc
Rhoda E
RE
Maguire
Janet J
JJ
Davenport
Anthony P
AP
D000818:Animals; D006724:Hoof and Claw / Q000098:blood supply*; D006736:Horses; D009479:Neuropeptides / Q000494:pharmacology*; D017981:Receptors, Neurotransmitter / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*
D009479:Neuropeptides; D017981:Receptors, Neurotransmitter; C082444:neuromedin U receptor; C056900:neuromedin U