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- Title
Evidence of a role for NK[sub1] and CGRP receptors in mediating neurogenic vasodilatation in the mouse ear.
- Authors
Grant, Andrew D.; Gerard, Norma P.; Brain, Susan D.
- Abstract
1 The aims of this study were to develop a technique to measure blood flow in the mouse ear and to investigate the nature of the vasodilator mediator(s) involved in the response to capsaicin. 2 The response to capsaicin, applied topically, was investigated in anaesthetized CD1 or Sv129 + C57BL/6 wild-type (+/+) or NK[sub 1] receptor knockout mice (-/-). Blood flow was assessed by laser Doppler flowmetry and oedema formation by [sup 125]I-albumin accumulation. 3 Capsaicin induced significant increases in blood flow (0.2-200 µg in 20 µl) and oedema (2200 µg in 20 µl). The oedema response was absent in NK[sub 1]-/- mice and NK[sub 1]+/+mice treated with the selective NK[sub 1] receptor antagonist SR140333 (480 nmol kg[sup -1]) as expected. Furthermore, the capsaicin-evoked increase in blood flow was significantly potentiated in the knockout mice (203% of wild-type response, P < 0.05) and wild-type mice treated with SR140333 (201%, P < 0.05). 4 The CGRP receptor antagonist CGRP[sub 8-37] (400 nmol kg[sup -1]) had no effect on capsaicin-induced blood flow in NK[sub 1]+/+mice but abolished the increased blood flow to capsaicin in NK[sub 1]-/-, and NK[sub 1]+/+wild-type mice pre-treated with SR140333. 5 The results indicate that neurogenic vasodilatation can be measured in the mouse ear. The capsaicin-induced increased blood flow involves activation of, and possible interactions between, both NK[sub 1] and CGRP[sub 1] receptors.
- Subjects
CALCITONIN gene-related peptide; SUBSTANCE P; VASODILATORS
- Publication
British Journal of Pharmacology, 2002, Vol 135, Issue 2, p356
- ISSN
0007-1188
- Publication type
Article
- DOI
10.1038/sj.bjp.0704485