title: Characterization of the responses of equine digital veins and arteries to calcitonin gene-related peptide.
abstract: OBJECTIVE
  To compare responses of equine digital arteries (EDAs) and veins (EDVs) to human-αcalcitonin gene-related peptide (hαCGRP), evaluate effect of the endothelium, and characterize receptors and sources of endogenous CGRP.
  
  
  METHODS
  Palmar digital vessels (5 to 9/experiment) from healthy adult horses killed at an abattoir.
  
  
  METHODS
  Vessel rings were mounted under tension in organ baths containing Krebs-Henseleit solution at 30 °C, with relaxation responses examined in vessels preconstricted with a thromboxane-mimetic (3 × 10(-8)M). Responses of endothelium-intact (+e) and -denuded (-e) EDAs and EDVs to hαCGRP C10(-10) to 3 × 10(-7)M) were compared. Following incubation with an hαCGRP receptor antagonist (hαCGRP(8-37); 1 μM), responses of EDA(-e) and EDV(-e) to hαCGRP (10(-7)M) were obtained. Responses of endothelium-intact and -denuded arteries and veins to hαCGRP (3 × 10(-7)M) or capsaicin (10(-5)M) were evaluated as well as responses of endothelium-intact and -denuded EDA and EDV to hαCGRP (10(-10) to 10(-6)M) after incubation with endothelin-1 (ET-1; 10(-12)M).
  
  
  RESULTS
  hαCGRP resulted in nonendothelium, concentration-dependent relaxation in EDAs and EDVs, with greater responses in EDAs. Treatment with hαCGRP(8-37) had minimal effect on responses to hαCGRP in either vessel type. Capsaicin induced relaxation in both vessel types. There were no differences between responses to hαCGRP for vessels pretreated with ET-1 or vehicle.
  
  
  CONCLUSIONS
  Both hαCGRP and capsaicin induced digital vasodilation unaffected by a functional endothelium. This suggested that endogenous CGRP likely emanates from sensory-motor nerves and may contribute to digital vasodilation.
authors: University Veterinary Hospital, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. lisa.katz@ucd.ie
authors: Lisa M
authors: LM
authors: Katz
authors: Celia M
authors: CM
authors: Marr
authors: Jonathan
authors: J
authors: Elliott
mesh_terms: D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002211:Capsaicin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D005552:Forelimb / Q000098:blood supply; D005947:Glucose; D006736:Horses / Q000502:physiology*; D006801:Humans; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000187:drug effects / Q000502:physiology; D014325:Tromethamine; D014664:Vasodilation; D014680:Veins / Q000187:drug effects* / Q000502:physiology
chemical_list: C074097:Krebs-Henseleit solution; D011450:Prostaglandin Endoperoxides, Synthetic; D018015:Receptors, Calcitonin Gene-Related Peptide; D014325:Tromethamine; C028429:U 44069; D005947:Glucose; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin