Studies on the Xanthurenic Acid-Insulin Complex

The distribution of added xanthurenic acid (XA) in the serum was studied by in vitro experiments with unlabeled and tritium labeled XA, both with healthy and diabetic serum, with and without added insulin. From this experiment it was elucidated that XA binds to both albumin and insulin fractions. The amounts of XA bound to-the serum protein are larger in a normal serum than a diabetic serum. The distribution of 131I-insulin in the serum was also studied. To elucidate the binding of XA to insulin, tritium labeled XA was injected to the rat and the sera were subjected to chromatography on the Sephadex column after it was treated with anti-insulin serum. The distribution of 3H-XA was checked in eluates. The result shows that injected 3H-XA binds to the circulating insulin and the resulting complex combines to the anti-insulin serum. Thus, we can confirm the binding of XA with insulin in the serum.