present as the injected 3H-25(OH)D3 while about 44% was in a
3H-labelled metabolite, co-chromatographing with 1,25(OH)2D3.
Analysis of the blood plasma of vitamin D-replete commercial
rainbow trout by competitive protein binding assays, showed that
the 25(OH)D concentration was below the level of detection of
1.2 ng/ml. However, the concentration of 1,25(OH)2D was
128
10 pg/ml.