scholarly journals Difference between in vivo and in vitro effects of propofol on defluorination and metabolic activities of hamster hepatic cytochrome P450-dependent mono-oxygenases

1995 ◽  
Vol 75 (4) ◽  
pp. 462-466 ◽  
Author(s):  
T L Chen ◽  
M J Wang ◽  
C H Huang ◽  
C C Liu ◽  
T H Ueng
Keyword(s):  
Cytochrome P450 ◽  
In Vitro Effects ◽  
Metabolic Activities ◽  
Hepatic Cytochrome

Inhibitory effects of H2-receptor antagonists on cytochrome P450 in male ICR mice

1995 ◽  
Vol 14 (8) ◽  
pp. 623-629 ◽  
Author(s):  
DH Kim ◽  
EJ Kim ◽  
SS Han ◽  
JK Roh ◽  
TC Jeong ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Liver Microsomes ◽  
Receptor Antagonists ◽  
Sleeping Time ◽  
Icr Mice ◽  
In Vitro Effects ◽  
Hexobarbital Metabolism ◽  
Dose Dependent

1 The present study was undertaken to examine the effects of H2-receptor antagonists including newly developed mifentidine derivatives, IY-80843 and IY-80845, on cytochrome P450(P450) in vitro and in vivo. 2 Initially, 3-methylcholanthrene-, phenobarbital-, ethanol- and dexamethasone-induced liver microsomes were prepared from male ICR mice to study in vitro effects of above chemicals on ethoxyresorufin O- deethylase(EROD), pentoxyresorufin O-dealkylase(PROD), p-nitrophenol hydroxylase and erythromycin N-demethy lase(ERDM) activities, respectively. It was found that hist amine, cimetidine and famotidine were not inhibitory to four enzyme activities. Meanwhile, mifentidine slightly inhibited EROD and PROD activities and its derivatives IY-80843 and IY-80845 strongly inhibited PROD, EROD and ERDM activities. 3 Prolongation of hexobarbital-induced sleeping time was determined in male ICR mice to confirm in vitro inhibito ry effects of mifentidine and its derivatives in vivo. It was observed that cimetidine, mifentidine, IY-80843 and IY- 80845 caused dose-dependent increases in the sleeping time, indicating the inhibition of P450 responsible for hexobarbital metabolism. 4 It was concluded that mifentidine and its derivatives are P450 inhibitors and that our newly synthesized IY-80843 is most inhibitory. 5 The present results indicate that mifentidine and its derivatives not only antagonise the H 2-receptor but also inhibit P450 enzymes.

scholarly journals beta-Naphthoflavone abolishes interrenal sensitivity to ACTH stimulation in rainbow trout

1998 ◽  
Vol 157 (1) ◽  
pp. 63-70 ◽  
Author(s):  
JM Wilson ◽  
MM Vijayan ◽  
CJ Kennedy ◽  
GK Iwama ◽  
TW Moon
Keyword(s):  
Cytochrome P450 ◽  
Rainbow Trout ◽  
Acth Stimulation ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Treated Fish ◽  
First Time ◽  
Hepatic Cytochrome ◽  
Stimulation Of

We report for the first time that beta-naphthoflavone (BNF) abolishes ACTH stimulation of cortisol production in rainbow trout (Oncorhynchus mykiss). There was significantly higher hepatic cytochrome P450 content and ethoxyresorufin O-de-ethylase and uridine-5'-diphosphoglucuronic acid transferase activities in BNF-treated fish than in sham-treated controls. BNF did not significantly affect either plasma turnover or tissue distribution of [3H]cortisol-derived radioactivity. Hepatic membrane fluidity and hepatocyte capacity for cortisol uptake were not altered by BNF as compared with the sham-treated fish. These results taken together suggest that BNF does not affect cortisol-clearance mechanisms in trout. A 3 min handling disturbance period elicited a plasma cortisol response in the sham-treated fish; however, the response in the BNF-treated fish was muted and significantly lower than in the sham fish. This in vivo response corroborates the lack of interrenal sensitivity to ACTH in vitro in the BNF-treated fish, suggesting that BNF affects the ACTH pathway in trout. Our results suggest the possibility that cytochrome P450-inducing compounds may affect cortisol dynamics by decreasing interrenal responsiveness to ACTH stimulation in fish, thereby impairing the physiological responses that are necessary for the animal to cope with the stressor.

In Vitro and In Vivo Evaluation of the Effect of Puerarin on Hepatic Cytochrome P450-Mediated Drug Metabolism

Planta Medica ◽  
2014 ◽  
Vol 80 (07) ◽  
pp. 561-567 ◽  
Author(s):  
Sang-Bum Kim ◽  
In-Soo Yoon ◽  
Kyu-Sang Kim ◽  
Sung-Jun Cho ◽  
Yeong Kim ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Drug Metabolism ◽  
In Vivo Evaluation ◽  
Hepatic Cytochrome

The Antiaggregating Activity of Clopidogrel Is due to a Metabolic Activation by the Hepatic Cytochrome P450-1A

1994 ◽  
Vol 72 (02) ◽  
pp. 313-317 ◽  
Author(s):  
P Savi ◽  
J Combalbert ◽  
C Gaich ◽  
M-C Rouchon ◽  
J-P Maffrand ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Metabolic Activation ◽  
Cytochrome P450 Enzymes ◽  
Specific Antibodies ◽  
Specific Induction ◽  
Antithrombotic Effects ◽  
Cytochrome P450 1A ◽  
Hepatic Cytochrome

SummaryClopidogrel and ticlopidine are two well known selective anti-ADP agents which are inactive in vitro and must be administered in vivo to fully exhibit their antiaggregating and antithrombotic effects. Since previous studies have clearly demonstrated that the activation steps take place in the liver, we examined the effect of specific induction or inhibition of cytochrome P450 subfamilies on the antiaggregating activity of clopidogrel. SKF 525-A, a global cytochrome P450 inhibitor, dramatically decreased the antiaggregating effect of clopidogrel, therefore indicating that cytochrome P450 enzymes are involved in the hepatic activation of clopidogrel. The efficacy of clopidogrel was increased in animals pretreated with 3-methylcholanthrene and (3-naphthoflavone, indicating that the cytochrome P450-1A subfamily pathway was mainly involved in the activating metabolism of clopidogrel. The use of specific antibodies directed against the various cytochrome P450 subfamilies ascertained this observation.

Mechanism-based inactivation of hepatic cytochrome P450 2C6 and P450 3A1 following in vivo administration of 3,5-diethoxycarbonyl-1,4-dihydro-2,6-dimethyl-4-ethylpyridine to rats: differences from previously observed in vitro results

1994 ◽  
Vol 72 (4) ◽  
pp. 397-401 ◽  
Author(s):  
S. M. Kimmett ◽  
J. P. McNamee ◽  
G. S. Marks
Keyword(s):  
Cytochrome P450 ◽  
Competitive Inhibition ◽  
Female Rats ◽  
Male Rats ◽  
Hepatic Microsomes ◽  
In Vitro Effects ◽  
P450 Isozymes ◽  
In Vivo Administration

Using progesterone 21-hydroxylase as a selective substrate for P450 2C6 in phenobarbital-treated male rats, and androstenedione and progesterone 6β-hydroxylases as well as erythromycin N-demethylase as selective markers for P450 3A1 in dexamethasone-treated female rats, we have shown that these P450 isozymes undergo mechanism-based inactivation after in vivo administration of 3,5-diethoxycarbonyl-1,4-dihydro-2,6-dimethyl-4-ethylpyridine (4-ethyl DDC). These results differ from our previous studies where no inactivation was observed after in vitro administration of 4-ethyl DDC to rat hepatic microsomes. We show that the differences between the in vivo and in vitro effects of 3,5-diethoxycarbonyl-1,4-dihydro-2,4,6-trimethylpyridine (DDC) analogues are due to the presence of residual 4-ethyl DDC in the in vitro experiments causing time-independent competitive inhibition and obscuring observation of mechanism-based inactivation.Key words: 3,5-diethoxycarbonyl-1,4-dihydro-2,6-dimethyl-4-ethylpyridine, cytochrome P450, steroid hydroxylation, rat hepatic microsomes.

In vivo and in vitro effects of helenalin on mouse hepatic microsomal cytochrome P450

1991 ◽  
Vol 41 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Dennis E. Chapman ◽  
David J. Holbrook ◽  
Stephen G. Chaney ◽  
Iris H. Hall ◽  
Lee Kuo-Hsiung
Keyword(s):  
Cytochrome P450 ◽  
Microsomal Cytochrome ◽  
Microsomal Cytochrome P450 ◽  
In Vitro Effects
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