Cerebrospinal Fluid Binding Capacity for Cyano- and Hydroxocobalamin

Abstract

Summary Using the same methods as in previous studies on the measurement of the vit. B₁₂ binding capacity in serum, the author has now investigated the binding capacity for cyano- and hydroxocobalamin in CSF by two microbiological methods and a dialysis technique. The findings were as follows: 1. There is no difference between the binding pattern in the CSF and serum for cyanocobalamin. Its binding capacity was approximately 1/10 of that found in serum. 2. Upon addition of more than 10–15 times the normal vit. B₁₂ content of the CSF, or 200-300 pg per ml and more, the binding capacity was found to be higher for hydroxocobalamin than for cyanocobalamin. 3. As the binding pattern for large quantities of hydroxocobalamin differs from that for the corresponding quantities of cyanocobalamin, it is concluded that the increased binding capacity for hydroxocobalamin may be due to a partial binding of this substance to proteins different from those to which cyanocobalamin is bound.