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EFFECT OF 6‐HYDROXYDOPAMINE ON [ 3 H]‐ADENINE NUCLEOTIDE AND [ 3 H]‐NORADRENALINE RELEASE FROM THE GUINEA‐PIG TAENIA CAECUM EVOKED BY ELECTRICAL FIELD STIMULATION, NICOTINE AND PERIVASCULAR NERVE STIMULATION
Author(s) -
KUCHII M.,
MIYAHARA J.T.,
SHIBATA S.
Publication year - 1974
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.1476-5381.1974.tb09677.x
Subject(s) - hydroxydopamine , stimulation , nicotine , guinea pig , caecum , taenia , biology , chemistry , anatomy , medicine , endocrinology , dopamine , neuroscience , immunology , dopaminergic , helminths
1 The effects of pretreatment of guinea‐pigs with 6‐hydroxydopamine (6‐OHDA) on the release of [ 3 H]‐noradrenaline and [ 3 H]‐adenine nucleotide following electrical field, nicotine and perivascular nerve stimulation of guinea‐pig taenia caecum were studied. 2 High frequency electrical field stimulation (15,30 Hz) released both [ 3 H]‐noradrenaline and [ 3 H]‐adenine nucleotide but low frequency (0.5, 5 Hz) stimulation, producing comparable muscle relaxation led only to [ 3 H]‐noradrenaline release. 3 6‐OHDA (50–200 mg/kg) pretreatment inhibited the muscle relaxation and, [ 3 H]‐noradrenaline release with electrical stimulation or with nicotine in isolated taenia but did not affect the release of [ 3 H]‐nucleotide. 4 A low dose of 6‐OHDA (50 mg/kg), completely inhibited the muscle relaxation and [ 3 H]‐noradrenaline release elicited by perivascular nerve stimulation. 5 Both tissue noradrenaline content and [ 3 H]‐noradrenaline uptake were decreased to the same extent by low as well as high doses of 6‐OHDA: noradrenaline content was reduced to 20% and uptake to 30% of the control value. 6 Catecholamine fluorescence disappeared from tissue layers of the taenia after treatment with a high dose of 6‐OHDA. 7 In these experiments the inhibitory action of electrical stimulation and nicotine on the taenia can be correlated better with noradrenaline than with nucleotide release.