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DEPRESSION BY MORPHINE OF EXCITATORY JUNCTION POTENTIALS IN THE VAS DEFERENS OF THE MOUSE
Author(s) -
HENDERSON G.,
NORTH R.A.
Publication year - 1976
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.1476-5381.1976.tb07672.x
Subject(s) - vas deferens , excitatory postsynaptic potential , depolarization , (+) naloxone , morphine , endocrinology , chemistry , stimulation , medicine , pharmacology , opioid , receptor , inhibitory postsynaptic potential
1 Intracellular recordings were made from smooth muscle cells of the mouse vas deferens. Excitatory junction potentials (e.j.ps) were evoked by stimulation of the intramural nerves. 2 Normorphine (50 n m ‐5 μ m ) depressed the amplitude of the e.j.p. The ED 50 was 430 n m . The latency of the e.j.p. and the resting membrane potential of the smooth muscle cells were unaffected by normorphine. 3 The depression of the e.j.p. by narcotic analgesic drugs was stereospecific. 4 Naloxone (100 n m ) completely reversed the depression of the e.j.p. produced by normorphine (1 μ m ). Naloxone (100 n m ) alone did not alter the amplitude of the e.j.p. 5 Normorphine (1 μ m ) did not prevent the depolarization of the smooth muscle cells produced by exogenous noradrenaline (10 μ m ). 6 It is concluded that narcotic analgesic drugs act directly upon the transmitter release sites to reduce the amount of noradrenaline liberated by each nerve impulse.