Inositol and the Respiration of Brain

By means of manometric measurements using the Warburg apparatus Das and Guha 1 claim to have shown that the oxygen consumption of various rat tissues is greater when inositol is present in the suspension medium than in control experiments in which it is absent. This effect was found in the case of brain, heart, kidney and liver tissue, being most marked in the case of brain tissue. After experiments of 2-3 hours’ duration Das and Guha found that when inositol was present unwashed brain tissue showed an oxygen consumption about 35% greater than that of the control (one experiment reported) and in the case of washed brain tissue (3 experiments reported) increases up to about 90% were found.

Since it has not been possible to ascribe any biochemical significance to the considerable amounts of inositol shown to be present in brain (Thudichum, 2 Young 3 ) the following work was undertaken to confirm and extend the above findings of Das and Guha.

The experimental procedure adopted in the case of the results recorded in Series I and II was that used by Das and Guha. White rats were used, and after decapitation the brains were removed as rapidly as possible, sliced, and the slices cut into small pieces. The tissue was transferred to Warburg flasks containing 1 ml. of Ringer-Locke solution, 1 ml. of Na₂HPO₄-NaH₂PO₄ buffer (pH 7.4) and either 0.5 ml. of water or 0.5 ml. of 0.1 M inositol solution. The CO₂ was absorbed with 0.2 ml. of 20% KOH solution in the inset of the flask, and the temperature of the thermostat was 37.3°C. In experiments in which washed brain was used, the finely cut tissue was washed twice in a centrifuge tube with Ringer-Locke solution as described by Das and Guha.