Inhibition of aldosterone formation by cortisol in rat adrenal mitochondria
In this work we confirm by a metabolic method the existence of at least two enzymes with 11β- and 18-hydroxylase activities in rat adrenal mitochondria. The method was based on the ability of cortisol (F), a foreign alternative substrate, to inhibit competitively metabolite productions from various...
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| Autores principales: | , , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0039128X_v60_n6_p447_Matkovic |
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| Sumario: | In this work we confirm by a metabolic method the existence of at least two enzymes with 11β- and 18-hydroxylase activities in rat adrenal mitochondria. The method was based on the ability of cortisol (F), a foreign alternative substrate, to inhibit competitively metabolite productions from various precursors. F inhibited a) aldosterone (ALDO) production from 11-deoxycorticosterone (DOC) without affecting the yields of corticosterone (B) and 18-hydroxy-11-deoxycorticosterone (18-OHDOC); b) 18-hydroxycorticosterone and aldosterone productions from B (Ki = 2.5 ± 0.5 μM); and c) ALDO production from 18-OHDOC. These results suggest the existence of two categories of enzymes with both 11β- and 18-hydroxylase activities, one comprising those that catalyze the conversions of DOC to B and 18-OHDOC (F-insensitive reactions [FIS]) and the other one comprising the enzymes involved in the conversions of B to 18-OHB and ALDO and that of 18-OHDOC to ALDO (F-sensitive reactions [FS]). The cloned enzymes CYP11B1 and CYP11B2 would pertain respectively to the FIS and FS categories. © 1995. |
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