Intracellular water and dry mass content as measured in bulk specimens by energy-dispersive X-ray microanalysis

Intracellular water content (IWC) was measured in freeze-fractured biological bulk specimens by means of energy-dispersive X-ray microanalysis. The method is based on the concentration differences of certain elements (potassium and phosphorus) between frozen-hydrated and frozen-dried states of the tissues as applied formerly to sectioned material by others. A new mathematical formula has been derived giving rather precise figures for IWC. No elemental standards are necessary for the measurement: one has to obtain only the peak to background ratios in wet and dry states of the cells. The method is sensitive enough to reveal age-dependent as well as drug-induced changes of IWC in liver and brain cells. The values obtained are quite comparable with the theoretically expected ones. Technical problems of the application of this method are discussed in detail.