Stimulierung von Kulturen embryonaler Rattenzellen durch Kälberserum. V. Verhalten der Inosit- und Cholinphospholipide / Stimulation of Embryonic Rat Cells by Calf Serum. V. Metabolism of Inositol- and Choline Phospholipids

Abstract

Embryonic rat fibroblasts were accumulated in G1-phase by incubation in serum-free medium and subsequently stimulated by the addition of calf serum. Using 3H-inositol and 14C-choline as label for phospholipids, the following results have been obtained: 1. Within a few minutes after stimulation up to 20 per cent of total phosphatidyl 3H-inositol is released from the membranes of prelabelled cells. This could not be detected with 14C-choline- prelabelled phospholipids. 2. Incorporation of 3H-inositol into phosphatidyl inositol, but not the uptake into the acid-soluble cell pool, is increased 30 and 45 min after stimulation by a factor of 2.8 and 3.3 respectively. Incorporation of 14C-choline at that time is significantly lower (2.0 and 1.6 respectively). 3. Incorporation of 32P inorganic phosphate into the lipid fraction of stimulated cells is 8.9 times higher after 10 min as compared with the controls.