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Sympathetic neurotransmission in the tail artery of aging rats
Author(s) -
Thorin Eric,
CapdevilleAtkinson Christine,
Corman Bruno,
Atkinson Jeffrey
Publication year - 1994
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.1476-5381.1994.tb16996.x
Subject(s) - phentolamine , endocrinology , medicine , neurotransmission , stimulation , sympathectomy , neurotransmitter , catecholamine , norepinephrine , biology , antagonist , chemistry , receptor , dopamine , central nervous system
1 Age‐related changes in noradrenergic neurotransmission in the tail arteries of three rat strains: outbred Wistar (WI/Ico), inbred Wistar (WAG/Rij) and inbred Fischer (F344) have been compared in the present study. 2 The arterial noradrenaline content varied from 5 to 10 ng mg ‐1 wet weight amongst young (3 to 6‐month old) representatives of each strain, but did not change with age. As protein content increased in senescent rats (24‐month old) by 30–40%, arterial tissue growth would not appear to receive a concomitant increase in sympathetic growth leading to relative, age‐related, structural sympathectomy in all strains. 3 The vasoconstrictor response to transmural electrical stimulation was diminished in adult and senescent rats of all strains. 4 As far as could be judged from the increase in noradrenaline release following perfusion with the α‐adrenoceptor antagonist, phentolamine (1 μ m ), the presynaptic α 2 ‐adrenoceptor‐mediated inhibition of noradrenaline release was intact in old representatives of all strains. 5 With blockade of the two main systems which control noradrenaline release in the rat tail artery, viz , neuronal reuptake with cocaine (4 μ m ) and presynaptic α 2 ‐adrenoceptors with phentolamine (1 μA), stimulation‐evoked release of noradrenaline was similar at all ages and in all strains. This suggests that in the rat tail artery the basic mechanism of neuronal release of noradrenaline is not functionally modified by aging. 6 We conclude that as sympathetic nerve terminals are apparently intact in all three strains of senescent rats used, the age‐associated deficit of α‐adrenergic control of vascular function is postsynaptic in nature.