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In vitro studies of lipid production of rat renal papillae with [2-14C]acetate or [2-14C]mevalonate have shown that sterologenesis is an important part of the total lipogenesis in this tissue. However, only a very small amount of labelled cholesterol could be detected in the sterol fraction. The lipid extract of tissue slices was directly subjected to thin-layer chromatography or reversed-phase column chromatography. The purified sterols were analyzed by radio gas-liquid chromatography on three different stationary phases, argentation thin-layer chromatography and digitonin thin-layer chromatography. By these techniques it was demonstrated that nearly all the sterol radioactivity could be accounted for by 4,4,14α-trimethyl-5α-cholesta-8,24-dien-3β-ol (lanosterol) and three sterols, which were slightly more hydrophilic than cholesterol. Two of these sterols had the same chromatographic mobilities as cholesta-5,24-dien-3β-ol (desmosterol) and 5α-cholest-7-en-3β-ol (lathosterol), respectively. The third compound, which accounted for the largest fraction of the radioactivity in the sterol fraction, could be tentatively identified as 5α-cholesta-7,24-dien-3β-ol.
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