Bhattacharyya A K, Connor W E, Spector A A
J Clin Invest. 1972 Aug;51(8):2060-70. doi: 10.1172/JCI107012.
The 24 hr sterol excretion from the entire skin surface was determined in six normal and five hypercholesterolemic (Type II) patients fed a controlled, eucaloric diet containing 400 mg of plant sterols. All subjects received radiolabeled cholesterol intravenously in order to measure cholesterol turnover and exchange. The 24 hr skin surface lipids were collected subsequently at intervals of 7-10 days. Sterols were quantified and identified by a combination of thin-layer and gas-liquid chromatographic methods. The mean 24 hr excretion of cholesterol in milligrams was 82.6 in the normal subjects and 82.7 in the hypercholesterolemic patients. Cholesterol constituted 89% of the total sterol excretion through the skin surface in both groups. The specific radioactivity of cholesterol in the skin surface lipids increased gradually after the intravenous administration of the isotope. Within 4-5 wk the specific activity equaled and then remained higher than that of the plasma up to 10 wk. These specific activity curves suggested that, for at least some of skin surface cholesterol, there was a precursor-product relationship between the plasma cholesterol and the skin cholesterol. The presence of plant sterols, beta-sitosterol, campesterol, and stigmasterol in the skin surface lipids of man has not been reported previously. We identified these sterols in the skin surface lipids of all of our subjects. They constituted about 7% of the total skin surface sterols. The occurrence of plant sterols in the skin surface lipids suggested that plasma sterols were transferred from the plasma into the skin. 1-2% of the skin surface sterols were tentatively identified as lathosterol and lanosterol. The present study documented that a significant amount of cholesterol was excreted from the skin surface and that probably there was a net transfer of plasma cholesterol into the skin surface lipids. Both normal subjects and hypercholesterolemic patients excreted similar amounts of cholesterol per day into the skin surface lipids. We suggest that this daily loss of cholesterol from the skin surface may need to be considered in sterol balance studies.
在六名正常人和五名高胆固醇血症（II型）患者中测定了整个皮肤表面24小时的甾醇排泄量，这些患者食用含有400毫克植物甾醇的对照、等热量饮食。所有受试者静脉注射放射性标记的胆固醇，以测量胆固醇的周转率和交换情况。随后每隔7 - 10天收集一次24小时皮肤表面脂质。通过薄层色谱法和气液色谱法相结合的方法对甾醇进行定量和鉴定。正常受试者24小时胆固醇排泄量的平均值为82.6毫克，高胆固醇血症患者为82.7毫克。在两组中，胆固醇占通过皮肤表面排泄的总甾醇的89%。静脉注射同位素后，皮肤表面脂质中胆固醇的比放射性逐渐增加。在4 - 5周内，比活性达到并随后一直高于血浆，直至10周。这些比活性曲线表明，至少对于皮肤表面的一些胆固醇而言，血浆胆固醇与皮肤胆固醇之间存在前体 - 产物关系。人体皮肤表面脂质中植物甾醇、β - 谷甾醇、菜油甾醇和豆甾醇的存在此前尚未见报道。我们在所有受试者的皮肤表面脂质中鉴定出了这些甾醇。它们约占皮肤表面总甾醇的7%。皮肤表面脂质中植物甾醇的出现表明血浆甾醇从血浆转移到了皮肤中。皮肤表面甾醇的1 - 2%初步鉴定为羊毛甾醇和羊毛脂甾醇。本研究证明，大量胆固醇从皮肤表面排泄，并且可能存在血浆胆固醇向皮肤表面脂质的净转移。正常受试者和高胆固醇血症患者每天排泄到皮肤表面脂质中的胆固醇量相似。我们建议在甾醇平衡研究中可能需要考虑皮肤表面每天的胆固醇损失。
