title: Effect of nitric oxide synthase inhibitor (L-NAME) on substance P-induced vasodilatation in the dental pulp.
abstract: OBJECTIVE
  To investigate the vasodilator mechanisms of pulpal vessels, especially the involvement of nitric oxide (NO), during pulpal inflammation.
  
  
  METHODS
  Eleven cats were prepared for intra-arterial administration of test agents through a lingual artery. The pulpal blood flow was measured by laser Doppler flowmetry from ipsilateral mandibular canine teeth. By using the NO synthase (NOS) inhibitor N(G)-nitro L-arginine methyl ester (L-NAME), the effects of L-NAME on various vasodilators, such as Substance P (SP)-, calcitonin-gene related peptide (CGRP)-, and papaverine-induced vasodilatation, were compared in vivo in 11 feline dental pulps.
  
  
  RESULTS
  L-NAME pretreatment potentiates SP-induced vasodilatation for a duration of approximately 5 h. The increase of pulpal blood flow ranged from 91.47 to 109.91%, which was significantly different from SP injection alone (48.79%, P < 0.05). Other vasodilators such as CGRP and papaverine did not respond to L-NAME pretreatment.
  
  
  CONCLUSIONS
  This study demonstrates that NOS inhibitor L-NAME administration alone has insignificant effects on pulpal blood flow, although L-NAME pretreatment can potentiate SP-induced vasodilatation, probably via increased activity in the enzyme guanylate cyclase. CGRP and papaverine did not respond to L-NAME pretreatment, indicating that they are not mediated via an endothelium-dependent mechanism.
authors.affiliation: Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Hsu
authors.forename: Y-T
authors.initials: YT
authors.lastname: Jou
authors.forename: R
authors.initials: R
authors.lastname: Wong
authors.forename: B
authors.initials: B
authors.lastname: Karabucak
authors.forename: S
authors.initials: S
authors.lastname: Simchon
authors.forename: S
authors.initials: S
authors.lastname: Kim
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D002415:Cats; D003782:Dental Pulp / Q000098:blood supply*; D004730:Endothelium, Vascular / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D020078:Neurogenic Inflammation / Q000503:physiopathology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010208:Papaverine / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D013373:Substance P / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009569:Nitric Oxide; D013373:Substance P; D010208:Papaverine; D019001:Nitric Oxide Synthase; D015740:Calcitonin Gene-Related Peptide; D019331:NG-Nitroarginine Methyl Ester