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Interactions of dopamine and the release of [ 3 H]‐taurine and [ 3 H]‐glycine from the isolated retina of the rat
Author(s) -
Pycock C. J.,
Smith L. F. P.
Publication year - 1983
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.1476-5381.1983.tb09404.x
Subject(s) - taurine , dopamine , depolarization , potassium , retina , glycine , endocrinology , inhibitory postsynaptic potential , neurotransmitter , medicine , chemistry , biophysics , biology , amino acid , biochemistry , neuroscience , central nervous system , organic chemistry
1 The dose‐related, calcium‐dependent, potassium‐stimulated release of preloaded [ 3 H]‐dopamine from the superfused rat retina has been demonstrated. 2 A high‐affinity uptake system for dopamine exists in rat retina in vitro; K m value was calculated as 1.89 μ m , V max value as 1.4 nmol g −1 tissue h. −13 Dopamine (0.8 and 4 m m ) inhibited the spontaneous release of [ 3 H]‐glycine from retina, and in the case of 0.8 m m dopamine this inhibitory effect was antagonized by 10 μ m (+)‐butaclamol but not by 10 μ m (−)‐butaclamol. 4 The potassium‐evoked (25 m m ) release of [ 3 H]‐glycine from rat retina was similarly inhibited by dopamine (0.4–4 m m ) in a dose‐related manner when added to the superfusate with the potassium. The effect of 0.8 m m dopamine was antagonized by 10 μ m (+)‐butaclamol but not by 10 μ m (−)‐butaclamol. 5 Dopamine (4 m m ) significantly reduced the spontaneous release of [ 3 H]‐taurine from rat retina. 6 The potassium‐stimulated (25 m m ) release of [ 3 H]‐taurine occurred after the cessation of the depolarizing stimulus. This delayed release of [ 3 H]‐taurine was unaffected if dopamine was applied to the superfusate at the same time as the potassium, but it was significantly reduced if dopamine (0.8 and 4 m m ) was applied after the depolarizing stimulus had been removed and during the actual amino acid release phase. 7 The inhibition of K + ‐stimulated (25 m m ) delayed release of [ 3 H]‐taurine by applying dopamine (0.8 m m ) after the depolarizing stimulus was blocked by 10 μ m (+)‐butaclamol but not by 10 μ m (−)‐butaclamol. 8 The results are discussed with respect to the possible neurotransmitter role for dopamine within the rat retina, and its possible interaction with glycine and taurine.