title: Depression by magnesium ion of neuronal excitability in tissue cultures of central nervous system.
abstract: Magnesium ion (Mg2+) in concentrations of 5-10 micron has been used to block synaptic transmission in in vitro preparations of central nervous system tissue. We have used explants of mouse cerebellum grown in culture to test whether significant levels of direct depression of neuronal membrane excitability could occur in such experiments. Using thresholds for antidromic activation and iontophoretically applied glutamate as tests of excitability, potent depressions of membrane excitability were found using 5-10 micron Mg2+. The additive depressant effects of increased Ca2+ concentrations provided further evidence that the effects were largely on membrane excitability and not on transmitter release mechanisms.
mesh_terms: D000818:Animals; D002531:Cerebellum / Q000166:cytology* / Q000187:drug effects; D046508:Culture Techniques; D003864:Depression, Chemical; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects*; D005971:Glutamates / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology*; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000502:physiology
chemical_list: D005971:Glutamates; D008274:Magnesium