Zur quantitativen Bestimmung mehrerer Stoffe in der Perilymphe einzelner Tiere

Summary

The biochemistry of inner ear fluids is relatively young. The knowledge in this area is meagre as compared to clinical chemistry. This depends on two facts. First the small volume of the samples, which urged the most investigators to pool the perilymph of many animals for one determination. Furthermore the contamination with blood, CSF or cells nearly can hardly be avoided. So the values known from the literature are quite divergent. Our own aim was to change consisting methods to be able to carry out the analysis in parts of a microlitre with reasonable accuracy. With this the purity of a sample can be proven within a part of it and there is enough material left to determine the metabolites. The electrolytes and the total protein content can be used to determine whether a sample is uncontaminated, because these substances have been analysed so often that the known values can be taken to be accurate.

Sodium and potassium have been determined with a flame photometer which measures both ions simultaneously. For that purpose 0.2 μl of the sample were diluted with 200 μl of a Lithium standard. For the determination of the total protein content 0.1 μl of the perilymph was spotted onto a cellulose acetate foil. After fixation and staining, the foil is made translucent. The evalution of the density of the dye is carried out by television densitometry. Glucose is analysed with glucose dehydrogenase with 0.3 μl of sample. For the determination of different proteins micromodifications of CAF-electrophoresis (0.2 μl) disc-electrophoresis (0.2 μl) or disc-Laurell-electrophoresis were used. After separation of the dansylated derivates with twodimensional micropolyamide TLC in 0.1 μl of perilymph 10 amino acids can be determined quantitatively by television densitometry of the fotografic negatives. To analyse 22 substances three times 2.3 μl of perilymph is necessary.

How important it is to prove the purity of the samples was shown by analysis of 14 perilymph samples. Out of nine in which no blood could be seen in the capillary with the operating microscope only four were not contaminated.

Intensive studies to develop these new methods were necessary to study experimentally induced pathologic changes in animals, because it is impossible to pool the samples as it was necessary up to now. It also makes it possible to investigate the inner ear fluid in a human being with a specific disease.