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Maitotoxin‐Induced Release of γ‐[ 3 H]Aminobutyric Acid from Cultures of Striatal Neurons
Author(s) -
Shalaby Ismail A.,
Kongsamut Sathapana,
Miller Richard J.
Publication year - 1986
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.1471-4159.1986.tb00631.x
Subject(s) - nitrendipine , marine toxin , chemistry , dihydropyridine , calcium , agonist , pharmacology , extracellular , biophysics , biochemistry , biology , toxin , receptor , organic chemistry
The potent marine toxin, maitotoxin, induced the release of γ‐[ 3 H]aminobutyric acid (GABA) from reaggregate cultures of striatal neurons in a dose‐dependent manner. Maitotoxin‐induced release occurred following a lag period of several minutes and was persistent. Release induced by 70 m M K + on the other hand was immediate and transient in nature. Co 2+ (3 m M ) and Cd 2+ (1 m M ) inhibited maitotoxin‐induced release of GABA as did removal of extracellular Ca 2+ . However, the organic calcium antagonists nisoldipine, nitrendipine, and D‐600 at concentrations of 10 −6 M did not block maitotoxin‐induced or 70 m M K + ‐induced release. High concentrations of D‐600 (10 −4 M ) partially blocked both maitotoxin‐ and 70 m M K + ‐induced release. The dihydropyridine calcium agonist BAY K8644 (10 −6 M ) did not enhance maitotoxin‐induced or 70 m M K + ‐induced release. Replacement of Na + in the incubation medium with choline led to an increased basal output of GABA and an apparent inhibition of the effect of maitotoxin. These data are discussed with reference to the hypothesis that maitotoxin can directly activate voltage‐sensitive calcium channels.