The Sensitivity of Aplysia Giant Neurons to Changes in Extracellular and Intracellular PO₂

Abstract

The effects of oxygen on the excitability of neurons have been studied in various groups of animals (Chalazonitis and Sugaya, 1958; Eccles et al, 1966; Chalazonitis, 1968; Kerkut and York, 1969; Steefin, 1975). However, the difficulty in recording intracellular PO₂ (I · PO₂) has prevented gathering of essential information concerning the effects of I · PO₂ on oxidative processes and on the bioelectric phenomena of neurons. Since many giant neurons in the Aplysia abdominal ganglion are easily identifiable, stable for several days and can be penetrated with newly improved PO₂ microelectrodes, we have employed them in a study of neuronal oxygen sensitivity. Chalazonitis has shown the effects of oxygen on the properties of the neuronal membrane in Aplysia by recording simultaneously, their bioelectrical properties and their I · PO₂ by spectrophotometry. In the present study, we have confirmed his results of hypoxic effects on change in membrane potential and spontaneous activity.