Microsomal protein, hepatic, effects

Pittz EP, Abraham R, Rourke D, et al. 1978. Effect of oral administration to mice of 30 ppm of mirex on the sodium dodecyl sulfate polyacrylamide gel electrophorectic patterns of hepatic microsomal proteins. Toxicol Appl Pharmacol 45(1) 335-336. 

Figure 3 Effects of p.o.-administered lentinan on the EROD andECOD activities. Mice were orally administered lentinan and intraperitoneally injected MC as described in Figure 1. The EROD and ECOD activities were measured in hepatic microsomal proteins.

Zang et al [140] reported the liver protective effects of the saponins isolated from A. membranaceus and A. sieversianus against chemical injury induced by CCU, D-galactosamine and acetaminophen in mice. In all cases there were positive activities and the saponins inhibited the rise in SGPT levels, decreased the malondialdehyde (MDA) content and increased the glutathione reduced (GSH) concentration in mouse liver. The same compounds were also evaluated in cultured rat hepatocytes, and the results indicated that the activity may be due to to the antioxidative activity of the saponins, since the content of liver protein in treated mice was more than the control. Moreover, in all treated mice, the level of hepatic microsomal cytochrome P-450 was increased. The liver metabolism and immunoregulating action produced by saponins may be also involved in their hepato-protective effects. Similar results were obtained by Zhang et al [141] when they studied the activity in vitro and... 

Warfarin is rapidly and nearly completely absorbed by the oral route. Peak plasma levels typically occur within 2-8 h. Warfarin is highly protein bound 97-99%. The volume of distribution approximates 0.151 kg Warfarin is extensively metabolized by hepatic microsomal enzymes. The primary metabolites are 6- and 7-hydroxy warfarin via oxidation and several warfarin alcohols via reduction. The warfarin alcohols retain weak anticoagulant activity. The metabolites undergo enterohepatic circulation. Approximately 85 % of warfarin appears in the urine as metabolites. Less than 1% or 2% appears in the urine unchanged. Warfarin metabolites are also excreted in the stool. The plasma half-life varies widely, from 10 to 80 h it is typically 36-44 h. The duration of clinical effects can significantly exceed the half-life of warfarin. (Note There are many drug interactions with warfarin the reader is referred to a standard pharmacology text for further details.)... 

TABLE 5.17 Effect of reduced protein diet on hepatic microsomal enzyme activity in rats... 

Bremer and Gloor [40] concluded that enzymes for both reactions were present in hepatic microsomes, but recent studies with microsomes of rat [40-42] and human liver [43] have confirmed the presence of only one enzyme, CoA ligase. The assay system, essentially that for long-chain acyl-CoA ligase [42,43], includes 50 mM NaF, a phosphate buffer (pH 7.5), the enzyme preparation, and constituents of Eqn. 1. Product formation was linear up to 12 min with added protein (between 0.1 and 1.2 mg) from a crude microsomal fraction. Sterol carrier protein [44], cysteine or nicotinamide [38,40] were without effect. This rate-limiting enzyme in the two-step sequence catalyzing conjugation of bile acids exhibits a diurnal variation such that the time of maximum enzyme activity coincides with predicted maximum activity of cholesterol 7a-hydroxylase and the time of maximal biosynthesis of bile acids [45]. The enzyme has not been purified. 

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