JPET

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sherry, J. H.
Right arrow Articles by Colby, H. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sherry, J. H.
Right arrow Articles by Colby, H. D.

Metabolism of spironolactone by adrenocortical and hepatic microsomes: relationship to cytochrome P-450 destruction

JH Sherry, JP O'Donnell, L Flowers, LB Lacagnin and HD Colby

Previous investigations have established that spironolactone (SL) is converted to a reactive metabolite by adrenocortical NADPH-dependent enzymes, resulting in the destruction of microsomal cytochrome(s) P-450 and decreases in steroid hydroxylase activities. Hepatic microsomes, by contrast, do not activate SL. Studies were done to characterize the activation pathway by comparing adrenal with hepatic metabolism of SL in guinea pigs. In the absence of NADPH, both adrenal and hepatic microsomal preparations converted SL to its deacetylated metabolite, 7 alpha-thio-SL. NADPH had no effect on hepatic SL metabolism but stimulated adrenal metabolism of SL. In the presence of NADPH, very little 7 alpha-thio-SL was recovered from the adrenal incubations, suggesting that the 7 alpha-thio-SL was further metabolized by NADPH- dependent enzymes. The latter hypothesis was confirmed by incubating microsomal preparations with 7 alpha-thio-SL as the substrate. In the presence of NADPH, 7 alpha-thio-SL was rapidly metabolized by adrenal microsomes but was not metabolized by hepatic preparations. Under the same incubation conditions, 7 alpha-thio-SL promoted the destruction of adrenal cytochrome(s) P-450 but had no effect on hepatic monooxygenases. 7 alpha-Thio-SL was far more potent than SL in promoting the destruction of cytochrome(s) P-450, suggesting that the metabolite might be an intermediate in the actions of the parent compound. Indeed, inhibition of SL conversion to 7 alpha-thio-SL by the esterase inhibitor, diethyl p-nitrophenyl phosphate blocked the effects of SL on adrenal cytochrome(s) P-450. Diethyl p-nitrophenyl phosphate did not affect the actions of 7 alpha-thio-SL on cytochrome(s) P- 450.(ABSTRACT TRUNCATED AT 250 WORDS)

Volume 236, Issue 3, pp. 675-680, 03/01/1986
Copyright © 1986 by American Society for Pharmacology and Experimental Therapeutics




This article has been cited by other articles:


Home page
 Drug Metab. Dispos.Home page
P. J. Murphy
The Development of Drug Metabolism Research as Expressed in the Publications of ASPET: Part 3, 1984-2008
Drug Metab. Dispos., October 1, 2008; 36(10): 1977 - 1982.
[Abstract] [Full Text] [PDF]


Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
All ASPET Journals Molecular Pharmacology Pharmacological Reviews
Molecular Interventions Drug Metabolism and Disposition

Copyright © 1986 by the American Society for Pharmacology and Experimental Therapeutics.