Eighteen-deoxyaldosterone and other less polar forms of 18-hydroxycorticosterone as aldosterone precursors in rat adrenals.
Samples containing as precursors either 18-hydroxycorticosterone (18-OH-B) in its M form, or this converted to less polar forms at pH 2 (ACM), or M or ACM enclosed in liposomes from adrenal lipids were incubated at pH 7.4, 4.8 or 3.3 in the presence or absence of quartered rat adrenals for 1 and 2 h. Optimal (10%) yields of aldosterone were obtained when (a) ACM was incubated at pH 4.8 and (b) M enclosed in liposomes was suspended in buffer and shaken without enzyme at pH 3.3. When conditions (a) were supplemented with malate and NADP, 16% of ACM was converted to aldosterone. ACM contained 80% of a fraction which, according to 13C NMR spectroscopy, was identical to 18-deoxyaldosterone (18-DAL). Experiments in which radioactivity from corticosterone (B) or M was trapped by radioinert M or 18-DAL disclosed a pathway comprising sequentially B, 18-OH-B, 18-DAL and aldosterone, and the combined evidence of this work, an enzymatic hydroxylation of 18-DAL to aldosterone.
D015069:18-Hydroxycorticosterone / Q000378:metabolism*; D000311:Adrenal Glands / Q000378:metabolism*; D000450:Aldosterone / Q000031:analogs & derivatives* / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D003345:Corticosterone / Q000031:analogs & derivatives*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008081:Liposomes / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats
D008081:Liposomes; C020274:18-deoxyaldosterone; D000450:Aldosterone; D015069:18-Hydroxycorticosterone; D003345:Corticosterone