Abstract
Methods were developed for the determination of HMG CoA (3-hydroxy-3-methylglutaryl CoA) reductase activity in subcellular fractions of intestinal mucosa and liver of Wistar strain rats. In the liver, reductase activity was located exclusively in the microsomal fraction. In the intestinal mucosa, activity was found in both mitochondrial and microsomal fractions of crypt cells but not of villi. The microsomal HMG CoA reductases of liver and intestinal mucosa had similar kinetic characteristics and pH optima. However, the activity of the hepatic enzyme differed with age and sex of the experimental animals while that of the intestinal crypt cells did not. Cholestyramine treatment enhanced the activity of the microsomal HMG CoA reductase in both liver and intestinal mucosa. Reductase activity of the intestinal crypt cells was elevated in both jejunum and ileum. The greatest stimulation, both relatively and absolutely, was observed in the distal half of the jejunum.
Highlights
F 3-hydroxy-3-methylglutaric acid or 3hydroxy-3-methylglutaryl (HMG) CoA (3-hydroxy-3-methylglutaryl CoAre)ductase activity in subcellular fractions of intestinal mucosa and liver of Wistarstrain rats
The activity of the hepatic enzyme differed with age and sex of the experimentalanimals while that of theintestinalcrypt cells did not.Cholestyraminetreatmentenhanced the activity of the microsomal HMG CoA reductase in bothliver and intestinalmucosaR. eductaseactivity of the intestinal crypt cellswas elevatedinbothjejunum and ileum
On the basis of recentstudies Weis and Dietschy [13] arrived at the conclusion that cholesterol biosynthesis (i.e., H M G CoA reductaseactivity) of theintestinal mucosa is largelycontrolled by thecirculating bile acid pool whilehepatic cholesterol biosynthesis is regulatedby cholesterol undergoingenterolymphatic circulation
Summary
F HMG CoA (3-hydroxy-3-methylglutaryl CoAre)ductase activity in subcellular fractions of intestinal mucosa and liver of Wistarstrain rats. 13, 1972 of microsomal H M G CoA reductase of liver and intes- cell fractions were carried out asdescribed above for the tinal mucosa in the same animal and illustrates the effect of . The supernatant solution was centrifuged at [3-14C]HMG CoA, 0.2 m ; and microsomal protein, 6700 g for 10 min to sediment the mitochondrial fraction.
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