X-irradiation attenuates relaxant responses in the rabbit ear artery.
1. The relaxant actions of acetylcholine, substance P and calcitonin gene-related peptide, and the levels of neuropeptide Y and calcitonin gene-related peptide were assessed in the rabbit central ear artery 1, 4 and 6 weeks after a single dose of 45 Gy X-irradiation, a dose similar to that used clinically in intraoperative radiotherapy. 2. Relaxant responses induced by acetylcholine and substance P (both endothelium-dependent) and calcitonin gene-related peptide (endothelium-independent) were reduced, and endogenous neuropeptide Y and calcitonin gene-related peptide levels were unaffected after X-irradiation. 3. The mechanism(s) by which a single dose of 45 Gy X-irradiation may selectively damage relaxant, but not direct, contractile responses of the smooth muscle (as we have shown previously) of the rabbit central ear artery are discussed.
Maynard
K I
KI
Department of Anatomy and Developmental Biology, University College London.
Stewart-Lee
A L
AL
Milner
P
P
Burnstock
G
G
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000528:radiation effects; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism / Q000494:pharmacology*; D004431:Ear, External / Q000098:blood supply*; D009478:Neuropeptide Y / Q000378:metabolism*; D011817:Rabbits; D013373:Substance P / Q000494:pharmacology*; D014664:Vasodilation / Q000528:radiation effects*
D009478:Neuropeptide Y; D013373:Substance P; D015740:Calcitonin Gene-Related Peptide; D000109:Acetylcholine