Use of isotopically radiolabelled GM3 ganglioside to study metabolic alterations in Salla disease.

We report the preparation of radioactive GM3 ganglioside and its use in the study of sialic acid storage disorders. For the first time GM3 was isotopically radiolabeled in three positions of the molecule: at the sialic acid acetyl group, [3H-Neu5Ac]GM3, at the C1 of the fatty acid moiety, [14C-Stearoyl]GM3, and at C3 of sphingosine, [3H-Sph]GM3. The radioactive GM3 administered to cultured human fibroblasts from a patient suffering from Salla disease was taken up by the cells and metabolized. An analysis of the distribution of radioactivity within the ganglioside metabolic derivatives showed an accumulation of free sialic acid and ceramide in the pathological cells.