The effect of intracerebral ouabain administration on the composition of edema fluid isolated from cats with cold-induced brain edema

Brain edema fluid was collected from cats with a freezing lesion in the left parietal cortex by the insertion into the brain of needles containing nylon wicks and connected to polyethylene tubes. The edema fluid samples which accumulated in the polyethylene tubes were regularly analyzed for Na + and K + content, colloid osmotic pressure, lactate dehydrogenase and creatine phosphokinase activity, and 99mTc-albumin radioactivity; the albumin tracer being introduced intravenously at the time of cold-injury. One series of cats received an intracerebral injection of ouabain solution, the control series an intracerebral injection of saline, at 100 min after the cold-injury. The ouabain injection was followed by an increase of K + content, LDH and CPK activities but a decrease of Na + concentration in the edema fluid, attributable to a concentration of solutes in the edema fluid as presumably water and Na + were shifted into the cells and hence the extracellular space was reduced.