Reference

Interactions of various 19-nor steroids with human placental microsomal cytochrome P-450 (P-450hpm)

Interactions of various 19-nor steroids with human placental microsomal cytochrome P-450 (P-450hpm). Juchau, Mont R.; Mirkin, David L.; Zachariah, Prince K. (Sch. Med., Univ. Washington, Seattle, Wash., USA). Chem.-Biol. Interact., 15(4), 337-47 (English) 1976. CODEN: CBINA8.In this article, certain chemicals are used. Some of their cas registry numbers are 360-70-3 and 434-22-0 DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Each of 7 19-norsteroids exhibited the capacity to facilitate the binding of CO to human placental microsomal cytochrome P-450 [9035-51-2] although quant. differences were shown to exist. In every case the facilitation was antagonized by androst-4-ene-3,17-dione [63-05-8]. 19-Norandrost-4-ene-3,17-dione (I) [734-32-7] produced the most pronounced effect followed by 19-nortestosterone [434-22-0], nandrolone 17-decanoate [360-70-3], norethandrolone [52-78-8], norgestrel [6533-00-2], norethynodrel [68-23-5], and norethindrone [68-22-4] in that order. All steroids investigated produced typical type I binding spectra when added to placental microsomes. Scatchard plots also indicated binding of each steroid to 2 sites-a high-affinity, low-capacity binding site and a low-affinity, high-capacity binding site. Correlations between affinity for either site and capacity to facilitate binding of CO to the cytochrome were not obsd. nor were there good correlations between maximal absorbance differences (.apprx.390-420 nm) producible and facilitation capacity. The capacity to facilitate CO binding appeared to reside in the absence of a chem. group substituted at the 10 position on mols. of androgenic steroids since all investigated steroids possessing 10-methyl or other 10-substituted groups either had no effect on the CO-binding spectrum or caused a displacement of CO from ferrous heme. In contrast, all steroids studied that lacked a substitution at C-10 (19-norsteroids) produced a facilitating effect on heme-ligand binding. .

Effects of cholestatic steroids on uptake and release of taurocholate in isolated hepatocytes

Effects of cholestatic steroids on uptake and release of taurocholate in isolated hepatocytes. Schwarz, L. R.; Schwenk, M.; Greim, H. (Abt. Toxicol., Ges. Strahlen-und-Umweltforsch., Neuherberg, Ger.). Bile Acid Metab. Health Dis., Proc. Bile Acid Meet., 4th, Meeting Date 1976, 145-50. Edited by: Paumgartner, G.; Stiehl, A. Univ. Park Press: Baltimore, Md. (English) 1977. CODEN: 36LLA3. DOCUMENT TYPE: Conference CA Section: 2 (Hormone Pharmacology) Section cross-reference(s): 13 Uptake and efflux of taurocholate (I) [81-24-3] were studied in isolated liver cells. Both processes are saturable, energy dependent and susceptible to protein reagents. Norethandrolone [52-78-8] 17-.beta. estradiol [50-28-2] and progesterone [57-83-0] inhibited I uptake into hepatocytes. Norethandrolone decreased efflux of the bile acid only at the very high concn. of 500 .mu.M. Thus, inhibition of I uptake may be involved in the pathogenesis of steroid-induced intrahepatic cholestasis.