Intracellular Mg2+ increases neuronal excitability.
Injection of Mg2+ into spinal motoneurons of cats leads to a depolarization, associated with a fall in membrane conductance, diminution in post-spike hyperpolarization, and increased excitability. This action has an apparent reversal level substantially more negative than the resting potential, and can be ascribed to a fall in K+ membrane conductance. Since these effects are opposite to those produced by intracellular Ca2+, it is suggested that Mg2+ probably competes with Ca2+ at the Ca2+-activated K+ ionophoreal free ionophores. Neuronal excitability can be regulated by the ratio of internal free Ca2+/Mg2+.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002415:Cats; D007478:Iontophoresis; D008274:Magnesium / Q000494:pharmacology*; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D013997:Time Factors
D009467:Neuromuscular Depolarizing Agents; D008274:Magnesium; D002118:Calcium