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Sympathetic neurotransmission in the rabbit isolated central ear artery is affected as early as one week following a single dose of X‐irradiation
Author(s) -
StewartLee A.L.,
Maynard K.I.,
Lincoln J.,
Burnstock G.
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb12126.x
Subject(s) - purinergic receptor , endocrinology , neurotransmission , medicine , stimulation , irradiation , catecholamine , agonist , adrenergic , norepinephrine , chemistry , sympathetic nervous system , biology , receptor , blood pressure , dopamine , physics , nuclear physics
1 The short‐term effect of a single dose of 4500 rad X‐irradiation on sympathetic neurotransmission (involving both noradrenergic and purinergic components) was assessed in the rabbit central ear artery, 1, 4 and 6 weeks post‐irradiation. 2 Neurally mediated contractions were reduced as early as 1 week post‐irradiation, with responses to lower frequency stimulation being initially most affected. This suggests that the purinergic component of the contractile response is affected earlier than the adrenergic component. 3 There was no change in the amplitude or sensitivity of treated preparations to the cumulative application of noradrenaline when compared with untreated preparations. In contrast, contractions to α,β‐methylene ATP (1 μ m ), a P 2 ‐purinoceptor agonist, were significantly increased at 4 and 6 weeks post‐irradiation, although not at 1 week post‐irradiation. 4 There were no apparent changes in the pattern of catecholamine fluorescence as a result of irradiation. However, the tissue content of noradrenaline was significantly reduced 6 weeks post‐irradiation when compared with control preparations. 5 It is concluded that damage to sympathetic cotransmission is one of the early effects of irradiation, with initial impairment predominantly of the purinergic component.