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Indirect evidence that purinergic modulation of perivascular adrenergic neurotransmission in the portal vein is a physiological process
Author(s) -
Burnstock Geoffrey,
Crowe Rahima,
Kennedy Charles,
Török Josef
Publication year - 1984
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.1476-5381.1984.tb10770.x
Subject(s) - purinergic receptor , adenosine , guinea pig , adrenergic , neurotransmission , medicine , endocrinology , biology , chemistry , receptor
1 The effects of adenine nucleotides and nucleosides on the contractile response to perivascular nerve stimulation were compared in the isolated portal vein of rabbit, rat and guinea‐pig. 2 2‐Chloroadenosine was more potent than adenosine and ATP, which were equipotent in producing inhibition of neurogenic contractions in the rabbit and rat via prejunctional P 1 ‐purinoceptors. 3 In contrast, neurogenic contractions of the guinea‐pig portal vein were not inhibited by adenosine and were potentiated by 2‐chloroadenosine and, to a lesser extent, by ATP. 4 Fluorescence histochemical localization of quinacrine, which binds to high levels of ATP, revealed a dense perivascular nerve plexus in the portal vein of rabbit and rat but not of guinea‐pig. 5 After chemical sympathectomy, quinacrine‐positive nerves persisted in the rabbit (supporting other evidence for the presence of purinergic nerves) but not in the rat (supporting other evidence for ATP as a cotransmitter in adrenergic nerves). 6 It is concluded that a prejunctional purinergic modulatory mechanism operates in adrenergic neurotransmission in the portal vein of rabbit and rat but not guinea‐pig, and it is suggested that this indicates a physiological mechanism.