INCREASE IN INCORPORATION OF INORGANIC PHOSPHATE-32 INTO PHOSPHATIDIC ACID IN BRAIN SLICES BY OUABAIN, EDTA OR A HIGH CONCENTRATION OF POTASSIUM

Abstract

Phospholipids are well known to be major constituents of the cell membrane and the importance of phospholipids in excitability of nerve tissue was shown by Tobias (1, 2). It has also been suggested that phospholipids may play a role in maintaining the unequal distribution of ions between the cell and its surroundings, for acidic phosphatides especially show a strong affinity for cations (3-5). Moreover, phosphatidic acid was postulated by Hokin and Hokin to be a carrier in ion transport process (6-9).
Since the report of Schatzmann, ouabain is recognized to block active ion transport selectively by acting on cell surface (10-14). On the other hand, addition of high concentration of potassium and EDTA to excitable tissues results in a decrease of resting membrane potential (15-18). Membrane resistence and threshold for excitation are raised by addition of calcium (18-20). Therefore, it is assumed that extracellular potassium and calcium concentrations are important factors to decide the state of excitable membrane.
On these considerations, metabolisms of phospholipids in brain slices with ouabain, EDTA and high concentration of potassium are examined in this study to know relationships between the states of membrane to regulate cation transport and metabolisms of phospholipids.
Preliminary notes on the effects of ouabain and potassium have already appeared (21, 22).