The Effect of High Pressure Air or Oxygen with and without Carbon Dioxide Added on the Catecholamine Levels of Rat Brain

The noradrenaline and dopamine levels in brain have been studied biochemically after exposure of rats to pure oxygen, oxygen and carbon dioxide, air, air and carbon dioxide at increased pressure up to 6 to 7 ata. After exposure to air with or without carbon dioxide added the catecholamine levels were unchanged, except for a tendency to decreased levels after about 5 hrs exposure to air without carbon dioxide at 7 ata. The behaviour of the rats during the exposure was unchanged. After exposure to oxygen decreased noradrenaline levels were found. Also the dopamine levels seemed to be decreased, but with carbon dioxide added to the oxygen the dopamine levels appeared to increase. During the oxygen exposure most rats developed convulsions. The onset of the convulsive state appeared earlier in rats exposed to oxygen with carbon dioxide added. The effects on the catecholamine levels are discussed with respect to e.g. the convulsions. Some symptoms at exposure to these gases at high pressure are suggested being due to effects on catecholamine or monoamine containing neurons in the brain.