Measurement of rate of rat liver sterol synthesis in vivo using tritiated water

Journal Article · Sun Jul 10 04:00:00 EDT 1977 · J. Biol. Chem.; (United States)

OSTI ID:7312214

Lakshmanan, M R; Veech, R L

The number of tritium atoms from tritiated water incorporated into cholesterol during its biosynthesis from mevalonate has been determined in vivo and correlated with the theoretically expected value. In vivo incorporation of tritium from tritiated water into hepatic sterol was determined as a function of various dosages of DL-mevalonate in mealfed rats. The number of microgram atoms of tritium incorporated per ..mu..mol of cholesterol synthesized reached a constant value of around 10.4 between the dosages of 2 to 10 mmol of DL-mevalonate injected/kg body weight. This value agrees closely with the theoretically calculated value of 9.5 based upon the biosynthetic steps from mevalonate to cholesterol. Furthermore, it was found that 2.2 ..mu..g atoms of tritium were incorporated into hepatic squalene from mevalonate at the saturating dose of 2 mmol of DL-mevalonate/kg body weight in meal-fed rats, thus agreeing with the theoretically expected value of 2.5. The total number of microgram atoms of tritium incorporated per ..mu..mol of cholesterol on the basis of the biosynthetic steps from acetyl-coenzyme A to cholesterol was calculated to be 14.5. Since 18 ..mu..mol acetyl units are utilized/..mu..mol of cholesterol synthesized, it follows that 1.24 ..mu..mol acetyl units are incorporated/..mu..g atom of tritium. Accordingly, the rate of hepatic sterol synthesis in meal-fed rats on the basis of tritium incorporation from tritiated water in vivo was determined to be 3.48 +- 0.15 ..mu..mol acetyl units/g wet weight of liver/h. The rate of hepatic sterol synthesis in meal-fed rats on the basis of mevalonate incorporation reached a saturation value of 3.33 +- 0.15 ..mu..mol acetyl units/g wet weight of liver/h. Such a close agreement between two independent methods strongly supports the validity of the tritium incorporation method for the accurate measurement of sterol synthesis in vivo.

• Research Organization: Saint Elizabeth's Hospital, Washington, DC
• OSTI ID: 7312214
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 252:13; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CHOLESTEROL
DIGESTIVE SYSTEM
GLANDS
HYDROXY ACIDS
HYDROXY COMPOUNDS
IN VIVO
LABELLED COMPOUNDS
LIVER
MAMMALS
MEASURING METHODS
MEVALONIC ACID
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RATS
RODENTS
STEROIDS
STEROLS
SYNTHESIS
TRITIUM COMPOUNDS
TRITIUM OXIDES
USES
VERTEBRATES