Problems connected with in vivo labelling of embryonic glycosaminoglycans with Na₂ ³⁵SO₄ in teratological studies

Summary

The time course in which radioactivity is found in maternal serum after a single injection of Na₂ ³⁵SO₄ may be drastically changed under the influence of drugs. This must influence the rate of incorporation of³⁵S labelled precursors into the GAG fractions of embryonic tissue. Therefore it is not possible to draw any conclusions from in vivo labelling experiments unless at least the change in the radioactivity of the maternal serum has been taken into consideration.

A method is presented which allows an evaluation of an effect of drugs on GAG also in such cases in which the availability of the isotope from the maternal organism is changed: instead of measuring the rate of incorporation into the total GAG, a subfractionation of GAG according to their anionic behaviour is performed. In a routine assay three fractions of GAG are obtained after fractionation on ECTEOLA-cellulose. The ratio of incorporation of radioactively labelled precursors into the different subfractions is taken as indication of an effect of a drug on GAG metabolism. As an example the effect of vitamin A and Na-salicylate is analysed.