Effect of diethylstilbestrol (DES) on intracellular Ca2+ levels in renal tubular cells

The effect of the estrogen diethylstilbestrol (DES) on intracellular Ca2(+) concentrations ([Ca2+](i)) in Madin Darby canine kidney (MDCK) cells was investigated, using the fluorescent dye fura-2 as a Ca2+ indicator. DES (10-50 muM) evoked [Ca2+], increases in a concentration-dependent manner. Extracellular Ca2+ removal inhibited 45 +/- 5% of the Ca2+ response. In Ca2+-free medium, pretreatment with 50 muM DES abolished the [Ca2+](i) increases induced by 2 muM carbonylcyanide m-chlorophenylhydrazone (CCCP; a mitochondrial uncoupler) and 1 muM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor); and pretreatment with CCCP and thapsigargin partly inhibited DES-induced [Ca2+](i) signals. Adding 3 mM Ca2+ increased [Ca2+]i in cells pretreated with 50 muM DES in Ca2+-free medium, suggesting that DES may induce capacitative Ca2+ entry. 17 beta -Estradiol (2-20 muM) increased [Ca2+](i), but 100 muM diethylstilbestrol dipropionate had no effect. Pretreatment with the phospholipase C inhibitor U73122 (1 muM) to abolish inositol 1,4,5-trisphosphate formation inhibited 30% of DES-induced Ca2+ release. DES (20 muM) also increased [Ca2+], in human normal hepatocytes and osteosarcoma cells. Cumulatively, this study shows that DES induced rapid and sustained [Ca2+], increases by releasing intracellular Ca2+ and triggering extracellular Ca2+ entry in renal tubular cells. (C) 2001 Elsevier Science Inc. Ail rights reserved.