[Effect of nitrite on the excitability of brain neurons in helix].

Incubation of the Helix brain in sodium nitrite (SN) decreased the firing threshold of silent neurones, increased firing rate and a response to stimulation, activated excitatory synaptic inputs of the neurones under study. The effects were stable but reversible. Rapid responses to the SN application were only shown for spontaneously active neurones. The SN effects were accompanied by a depolarisation and an increase in the input resistance. Inhibitor of the NO synthase exerted opposite effects to the NO donors and SN. A possible role of the NO and hypoxia in the SN effects, is discussed.