Investigations on vitamin D esters synthesized in rats. Turnover and sites of synthesis.
1. The tissue contents of vitamin D alcohol and ester were estimated in rats 5, 10, 24, 48 and 72hr. after peroral administration of [1-(3)H]cholecalciferol. 2. The total vitamin D in liver decreased in an exponential fashion from 19% of the dose at 5hr. to 0.6% at 72hr., but the ester content remained at a relatively constant low value from 5hr., so that by 72hr. it represented 67% of the total vitamin D. Vitamin D ester in kidney increased slowly to 48hr., but by 72hr. it was only 10% of the total vitamin D. 3. The small intestine, unlike liver and kidney, contained a higher content of vitamin D ester 10hr. after administration than at later times, and it is postulated that some vitamin D was esterified during absorption from the alimentary tract. 4. Plasma contained vitamin D ester at all time intervals, and it is suggested that ester found in liver and kidney could have been transported to these sites in the blood. 5. Thoracic-duct lymph was found to transport 43% of a peroral dose of vitamin D in 12hr., of which 1.4% was esterified. The fatty acid components of the lymph vitamin D ester, determined by two-dimensional thinlayer chromatography, were mainly palmitate (31%), stearate (25%), oleate (16%) and linoleate (16%). This pattern was similar to that previously found in liver.
D000818:Animals; D002404:Catheterization; D002762:Cholecalciferol / Q000378:metabolism*; D004032:Diet; D005227:Fatty Acids / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008196:Lymph; D051381:Rats; D012279:Rickets / Q000378:metabolism; D013897:Thoracic Duct / Q000502:physiology; D013997:Time Factors; D014316:Tritium; D014807:Vitamin D / Q000096:biosynthesis* / Q000097:blood
D005227:Fatty Acids; D014316:Tritium; D014807:Vitamin D; D002762:Cholecalciferol