A method is described for labeling plasma lipoprotein with radio-cholesterol. Almost all of the label is associated with high density lipoprotein as the free form. Lipoproteins labeled in this manner were injected intravenously into rats, and the distribution of cholesterol-4-C^14 was analyzed from a 24 to 48 hour study of plasmatic radioactivity, assuming a 4-compartment mammillary system. The venous disappearance curve of the radioactive cholesterol was physiological and was the type expected for free cholesterol in lipoproteins. The plasma cholesterol ester fraction was equilibrated within 12 hours after the intravenous administration of the label, and red blood cell cholesterol within 6 hours, with free cholesterol. It is indicated that the preparation prepared here can be applicable for the turnover study of cholesterol, particularly of the esterified form, in the blood-liver system.
リポ蛋白質態遊離コレステロール-4-C^14の調製法について記した.この標品をラットに静注した場合,血漿からのC^14の消失は注射直後より生理的曲線を画く.注射48時間後までの消失曲線はMatthewsにより解析された"4-compartment system"に相当した.エステル型コレステロールは静注12時間後で,また赤血球コレステロール(約99%は遊離型として存在する)6時間以後に遊離コレステロールとequilibrateした.この標品は注射直後におけるコレステロール,とくに種々のコレステロール・エステル成分の代謝研究に応用の広いことが示された.本研究は1962~64年,米国Harvard University, School of Public Health, Department of NutritionにおいてPostdoctoral Research Fellowとして行なつたものの一部である.著者の一人O. W. Portmanの現住所は,Oregon Regional Primate Research Center, Beaverton, Oregonである.