ADAPTATION OF CELLULAR-METABOLISM TO ANISOSMOTIC CONDITIONS IN A GLIAL-CELL LINE, AS ASSESSED BY C-13-NMR SPECTROSCOPY

C-13-NMR spectroscopy of perchloric acid and lipid extracts of F98 gli oma cells showed that volume-regulatory processes under anisosmotic co nditions were accompanied by marked alterations in cellular metabolism . Production of alanine, glutamate, and glycine from [U-C-13]-glucose is decreased under hypotonic stress and is oppositely increased under hypertonic stress. In contrast, degradation of these molecules is rais ed under hypotonic conditions and reduced under hypertonic conditions, Furthermore, phospholipid synthesis is decreased under hypertonic str ess and increased under hypotonic stress. Obviously, glial metabolism is directed under hypertonic conditions to maintain a high level of sm all, osmotically active molecules, whereas under hypotonic conditions molecular fragments are increasingly incorporated into the phospholipi ds and so do not contribute to the osmotic pressure. The latter is evo ked by the activation of membrane synthesis processes to compensate fo r stretching and/or damaging of the membranes due to cell swelling.