Vitamin D-deficient trout, weighing about 200 g, were fasted
for 24 h and then injected intraperitoneally with 30 ng [1,2-3H]
cholecalciferol in 100 ml propylene glycol. After a further 24 h
without food, the trout were killed and various tissues were
collected to measure the distribution of radioactivity. Surprisingly,
about 90% of the tritium dose was found as more polar metabolites
of vitamin D in the bile which had accumulated in the gall bladder
during the time of starvation. Hence, rather than using this small
dose of vitamin D to perform some functional role, it appeared that
it had been metabolically changed and excreted in bile