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INHIBITION OF SYNAPTOSOMAL NORADRENALINE UPTAKE BY VERATRIDINE, GRAMICIDIN D AND VALINOMYCIN
Author(s) -
White T. D.
Publication year - 1977
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1977.tb09608.x
Subject(s) - veratridine , valinomycin , gramicidin , chemistry , synaptosome , ionophore , extracellular , turbidimetry , biophysics , pharmacology , membrane , biochemistry , biology , sodium , sodium channel , organic chemistry
Abstract— —The effects of brief exposures of rat brain synaptosomes to veratridine, gramicidin D and valinomycin on noradrenaline uptake were investigated. All three drugs inhibited the Na + ‐dependent component of noradrenaline uptake by synaptosomes. These effects were independent of extracellular Ca 2 + concentrations, indicating that the reductions were not due to the release of newly accumulated noradrenaline. Gramicidin D reduced the V max for noradrenaline uptake, whereas veratridine and valinomycin reduced the V max and also increased the V m for uptake. Most of these findings can be explained on the basis of the effects that these drugs have on the inward‐directed electrochemical gradients for Na + across synaptosomal membranes, although, in the cases of veratridine and valinomycin, the elevated K m 's suggest that an impairment of noradrenaline binding to its carriers might also be involved.