Accession Number : AD0691775

Title :   EFFECTS OF pH AND pCO2 ALTERATIONS ON ELECTRICAL PARAMETERS AND ACTIVITY OF SINGLE IDENTIFIABLE NEURONS.

Descriptive Note : Final technical rept., Jul 67-Jan 69,

Corporate Author : COLLEGE DE FRANCE PARIS NATURALIA ET BIOLOGIA

Personal Author(s) : Chalazonitis,Nicolas

Report Date : MAY 1969

Pagination or Media Count : 31

Abstract : Possible excitatory and depressive actions of the CO2 - H(+) system on given model neurons of Aplysia californica were investigated through: (a) spectrophotometric recording of absorption changes, induced by CO2, of suitable pH indicators, injected into the ganglion; (b) simultaneous recording of concomitant changes in the bioelectric parameters; (c) establishing the relationship between pH and transmittancy changes giving the instantaneous pH of the glial space (perineuronal) during the pCO2 action; (d) establishing the relationship between pH and pCO2 in sea water (taken as a physiological solution for the isolated ganglion) allowing conversion of the instantaneous pH values into pCO2 values. Excitatory effects were demonstrated on the spontaneously active neurons, those firing with regular frequency as well as those giving sudden bursts on slow waves. Depressive effects were demonstrated on the stable membrane potential neuron (A neuron) and on some autoactive but arhythmic neurons, inhibitorily controlled. In the latter case, the depressive effects were found to be partly due to a decrease in the direct excitability of the examined neuron and partly to an increase of inhibitory input from associated interneurons. It was also found that chemosensitivity depends, among other things, on the level of the membrane potential during the CO2 action. In some cases, this dependence explains why neuronal chemosensitivity is a variable and instantaneous property. (Author)

Descriptors :   (*NERVE CELLS, SENSITIVITY), CARBON DIOXIDE, RESPONSE(BIOLOGY), NERVOUS SYSTEM, PHYSIOLOGY, PH FACTOR, CELLS(BIOLOGY), MEMBRANES, SENSITIVITY, SPONGES, MOLLUSCA, NERVE IMPULSES, FRANCE

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE