Effect of nitric oxide synthase inhibitor (L-NAME) on substance P-induced vasodilatation in the dental pulp.
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.
Hsu
Y-Y
YY
Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Jou
Y-T
YT
Wong
R
R
Karabucak
B
B
Simchon
S
S
Kim
S
S
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*
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