The mineralocorticoid antagonist activity of an 11 beta,18-oxidopregnane.
Removal of the 18-hydroxy group of the hemiacetal form of aldosterone transforms its activity from that of pure agonist to predominant antagonist. The 18-deoxy derivative possesses one third of the binding affinity of aldosterone for the cytoplasmic mineralocorticoid receptor of rat kidney and exhibits an approximate 2:1 antagonist to agonist ratio in both toad bladder and adrenalectomized rat bioassay systems. The promising properties of the 11 beta,18-oxidopregnane tested included very low androgen receptor affinity and approximately equal effectiveness in vitro and in vivo in displacing aldosterone from mineralocorticoid-binding sites in the rat.
D000450:Aldosterone / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001001:Anura; D001681:Biological Assay; D001693:Biological Transport, Active / Q000187:drug effects; D007668:Kidney / Q000378:metabolism; D000451:Mineralocorticoid Receptor Antagonists / Q000378:metabolism / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011987:Receptors, Steroid / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013329:Structure-Activity Relationship; D001743:Urinary Bladder / Q000187:drug effects
D000451:Mineralocorticoid Receptor Antagonists; D011987:Receptors, Steroid; D000450:Aldosterone; D012964:Sodium; D011188:Potassium