Animal experiment:

Rats: 11α- and 11β-OHP are dissolved in propylene glycol (100%) and infused at 3 and 10 μg/h, respectively, for 14 days. Control rats received vehicle only. BP is measured the day before pumps were implanted and on days 3, 7, 10, and 14 after implantation. Indirect systolic BPs are measured with a modified tail-cuff method[2].

11beta-Hydroxyprogesterone is a potent inhibitors of 11β-Hydroxysteroid dehydrogenase; also activates human mineralocorticoid receptor in COS-7 cells with an ED50 of 10 nM.

11OHP displays agonist mineralocorticoid activity. 11β-hydroxyprogesterone activates the transiently expressed hMR in COS-7 cells in a dose-dependent manner with an ED50 of 10 nM and stimulates Ams/sc in mpkCCDcl4 cells. Docking 11β-hydroxyprogesterone within the hMR-ligand-binding domain homology model reveals that the agonist activity of 11OHP is caused by contacts between its 11β-hydroxyl group and Asn770[1].

11β-hydroxyprogesterone causes a significant elevation in blood pressure within 3 days, an effect that persisted throughout the 14-day infusion. 11β-hydroxyprogesterone is potently hypertensinogenic in the rat and that this activity depends on an intact adrenal and at least in part on the activation of mineralocorticoid receptors[2].

[1]. Rafestin-Oblin ME, et al. 11beta-hydroxyprogesterone acts as a mineralocorticoid agonist in stimulating Na+ absorption in mammalian principal cortical collecting duct cells. Mol Pharmacol. 2002 Dec;62(6):1306-13. [2]. Souness GW, et al. 11 alpha- and 11 beta-hydroxyprogesterone, potent inhibitors of 11 beta-hydroxysteroid dehydrogenase, possess hypertensinogenic activity in the rat. Hypertension. 1996 Mar;27(3 Pt 1):421-5.