Evidence for the presence of 'ouabain like' compound in human cerebrospinal fluid.

Material extracted and partially purified from human cerebrospinal fluid (CSF) is capable of: a, inhibiting [3H]ouabain binding to rat brain synaptosomes; b, inhibiting the activity of purified pig kidney Na+,K+-ATPase; and c, inhibiting ouabain sensitive induced 86Rb influx to tissue cultured fibroblasts. These results demonstrate the existence of an 'ouabain like' compound (OLC) in human CSF, and are consistent with the hypothesis of the function of this compound as a neuromodulator.