Effects of 6-hydroxydopamine on pre- and post-junctional 5-HT sub(1)-like receptor-mediated responses in dog saphenous vein

To investigate whether 5-HT sub(1)-like receptor-mediated inhibition of adenosine 3': 5'-cyclic monophosphate (cyclic AMP) accumulation occurs in nerves or smooth muscle of saphenous vein, infusions of 6-hydroxydopamine (6-OHDA) were administered to dogs with the aim of inducing sympatheti...

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Published in:Naunyn-Schmiedeberg's archives of pharmacology 1993-01, Vol.347 (3), p.257-265
Main Authors: Medhurst, AD, Novotny, GEK, Parker, S G, Deighton, N M, Kaumann, A J
Format: Article
Language:English
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Summary:To investigate whether 5-HT sub(1)-like receptor-mediated inhibition of adenosine 3': 5'-cyclic monophosphate (cyclic AMP) accumulation occurs in nerves or smooth muscle of saphenous vein, infusions of 6-hydroxydopamine (6-OHDA) were administered to dogs with the aim of inducing sympathetic nerve damage. Disruption of nerve function by 6-OHDA was revealed by the lack of catecholaminergic fluorescence and neurogenic contractile responses in saphenous veins from dogs treated with 6-OHDA. In addition, severe impairment of neuronal uptake mechanisms were apparent since basal efflux of super(3)H-noradrenaline, electrically-evoked release of super(3)H-noradrenaline and remaining super(3)H-noradrenaline content were considerably reduced. Some super(3)H-noradrenaline was taken up and released in 6-OHDA-treated tissues which is consistent with the existence of nerve varicosities resistant to the present dosing regime of 6-OHDA, an observation substantiated by electron microscopy studies showing inconsistent lesions of nerve terminals.
ISSN:0028-1298