Provitamin D3 in tissues and the conversion of cholesterol to 7-dehydrocholesterol in vivo

Publisher Website
Google Scholar
Abstract
The properties of purified 7-dehydro- cholesterol were detd., and a method of correcting u.-v. absorption curves for irrelevant contributions was descr. and applied to sterol fractions prepared by an improved chromatographic method. The distr. of 7-dehydrosteroid was studied for various ox, rat and guinea pig tissues with the result that the small intestine is shown to be relatively rich, especially in the guinea pig. The 7-dehydrosteroid is concentrated mainly in the mucosa and lamina propria of the absorptive part (duodenum) of the guinea pig intestine; it tends to increase with increasing size, and when the animals exhibit liver tubercles. Cholesterol, administered orally, dissolved in ethyl myristate or oleate, is dehydrogenated in the wall of the small intestine. The dehydro-genase enzyme acts in the reverse sense on orally administered 7-dehydrocholesterol. Much of the administered sterol is metabolized during the 1st 24 hrs. after dosing.