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 assayed via its inhibition of 86Rb+uptake in human red blood cells in a fraction which was obtained from brain tissue by methanol extraction, chloroform treatment and purification of the water phase by C-18 HPLC. As compared to the contralateral hemispheres with an EOLF concentration of 605 ±71 pmol ouabain equivalents per g wet weight, the edematous hemisphere had significantly higher concentrations: 12 hours after cold injury it was 2600 ± 1762 pmol (p < 0.03) and fell to 857 ± 160 pmol ouabain equivalents/g wet weight after 24 hrs. Similar kinetics were evident for the EOLF concentrations in cerebrospinal fluid. It is suggested that the increase of EOLF in the edematous brain hemisphere may participate as a mediator in the development of vasogenic brain edema in the disturbance of the sodium metabolism.