ANOXIA-INDUCED FUNCTIONAL INACTIVATION OF NEONATAL RESPIRATORY NEURONS IN-VITRO

IN the isolated brain stem-spinal cord preparation of neonatal rats, r espiratory (C-4) activity persisted at reduced frequency during tissue anoxia. In seven biphasic expiratory (Bi-E) and in 12 of 22 inspirato ry (Insp) neurones, recorded with the 'blind' patch-clamp technique, a noxia evoked a persistent hyperpolarization by up to 16 mV whereas mem brane potential of the remaining Insp neurones depolarized slightly or remained unaffected. Respiration-related synaptic potentials and acti on potential discharges were blocked in all Bi-E and in about 50% of t he Insp neurones, whereas rhythmic activity persisted in the other cel ls. The results indicate that a major population of neonatal respirato ry neurones is functionally inactivated during anoxia. This mechanism might contribute to the anoxia tolerance of the immature brain.