THE ENDOGENOUS OUABAIN-LIKE SODIUM-PUMP INHIBITOR IN COLD INJURY-INDUCED BRAIN EDEMA

An endogenous ouabain-like factor (EOLF) was measured in brain tissue of cats 12 and 24 hrs after cold injury-induced edema. EOLF was assaye d via its inhibition of Rb-86+ uptake in human red blood cells in a fr action which was obtained from brain tissue by methanol extraction, ch loroform treatment and purification of the water phase by C-18 HPLC. A s compared to the contralateral hemispheres with an EOLF concentration of 605 +/- 71 pmol ouabain equivalents per g wet weight, the edematou s hemisphere had significantly higher concentrations: 12 hours after c old injury it was 2600 +/- 1762 pmol (p < 0.03) and fell to 857 +/- 16 0 pmol ouabain equivalents/g wet weight after 24 hrs. Similar kinetics were evident for the EOLF concentrations in cerebrospinal fluid. It i s suggested that the increase of EOLF in the edematous brain hemispher e may participate as a mediator in the development of vasogenic brain edema in the disturbance of the sodium metabolism .