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DOPAMINE AND THE DEPRESSANT ACTION OF MORPHINE ON STIMULATED GUINEA‐PIG ILEUM
Author(s) -
FERRI S.,
REINA R.,
SANTAGOSTINO A.
Publication year - 1977
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.1476-5381.1977.tb06972.x
Subject(s) - apomorphine , morphine , dopamine , myenteric plexus , (+) naloxone , phentolamine , pharmacology , chemistry , ileum , endocrinology , stimulation , medicine , opioid , dopaminergic , receptor , immunohistochemistry
1 Morphine reduces the amplitude of the contractions induced by electrical stimulation, in the myenteric plexus‐longitudinal muscle preparation of guinea‐pig ileum. Dopamine and apomorphine have the same effect but at much higher concentrations. 2 Dopamine, at concentrations lower than those which would normally be inhibitory, partially reverses the depressant effect of morphine. 3 Pre‐treatment of guinea‐pigs with 6‐hydroxydopamine results in a slight supersensitivity of innervated longitudinal muscle preparations to dopamine and has no effect on morphine activity. 4 Naloxone antagonizes the depressant effect of morphine but not that of dopamine or apomorphine. 5 The response of the ileum preparation to morphine is not affected by phentolamine or propranolol; the effect of dopamine, however, is abolished by α‐adrenoceptor blockade.