Hepatic microsomal activities, extrahepatic

Factors other than cytochrome P-450 also could be responsible for differences in extrahepatic vrs hepatic microsomal activities involved in IPO metabolism. For example, one experiment that suggested this showed that an antibody prepared against purified cytochrome b5 almost completely inhibited the metabolism of IPO by rat pulmonary microsomes, but it had little effect on IPO metabolism by rat hepatic microsomes(28). 

Evidence suggests that endosulfan can induce microsomal enzyme activity. Increased liver microsomal cytochrome P-450 activity was observed in male and female rats after single and multiple administrations of endosulfan (Siddiqui et al. 1987a Tyagi et al. 1984). Increased enzyme activity was observed in hepatic and extrahepatic tissues. Based on the increase in aminopyrine-A-demethylase and aniline hydroxylase activity, endosulfan has been shown to be a nonspecific inducer of drug metabolism (Agarwal et al. 1978). 

LC/MS/MS with selected reaction monitoring (SRM) offers a fast and simple means to analyze biological matrices, which is a key factor in high-throughput CYP inhibition screens using liver microsomes. Potentially, the LC/MS/MS technique is suitable for analyses of cocktail substrates in other in vitro drug metabolism evaluations such as CYP induction/activation assays, rapid analysis of pooled liver microsomes, rapid reaction phenotyping of tissue (hepatic and extrahepatic) samples, as well as evaluation of hepatocytes/tissue slice CYP activity. ° ... 

Clement B, Mau S, Deters S, et al. Hepatic, extrahepatic, microsomal, and mitochondrial activation of the n-hydroxylated prodrags benzamidoxime, guanox-abenz, and RO 48-3656 ([[l-[(2S)-2-[[4-[(hydroxyamino)iminomethyl]benzoyl] amino]-l-oxopropyl]-4-piperidinyl]oxy]-acetic acid). Drag Metab Dispos 2005 33 1740-1747. 

Hepatic and extrahepatic CarbE activities have been studied after the exposure of rats to polycyclic aromatic hydrocarbons. In dose- and time-dependent studies, benz(a)anthracene, benzo(a)pyrene, and 3-methylcholanthrene moderately induced the hepatic cytosolic and kidney microsomal CarbEs activities, while anthracene, phenanthrene, and chrysene had... 

---