The effect of 17 β-estradiol on intracellular calcium homeostasis in human endothelial cells

• Published in: European journal of pharmacology Vol. 630; no. 1; pp. 92 - 99
• Main Authors: Thor, Der, Uchizono, James A., Lin-Cereghino, Geoff P., Rahimian, Roshanak
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-03-2010; Elsevier
• Subjects: Adenosinetriphosphatase; Biological and medical sciences; Calcium; Calcium (intracellular); Calcium - metabolism; Cell Line; Chronic effects; Cofactors; Data processing; Endoplasmic reticulum; Endothelial cells; Endothelial Cells - drug effects; Endothelial nitric oxide synthase; Esters; Estradiol - pharmacology; Estrogen; Estrogen receptor alpha; Estrogen receptors; Estrogens - pharmacology; Homeostasis - drug effects; Humans; Medical sciences; Nitric-oxide synthase; Pharmacology. Drug treatments; Spectrofluorometry; thapsigargin; Western blotting; Endothelial nitric oxide synthase; Estrogen receptor alpha; Calcium; Estrogen; Human; Endothelial cell; Enzyme; Homeostasis; Inorganic element; Estradiol; Ovarian hormone; Nitric-oxide synthase; Endothelium; Estrogen receptor α; Oxidoreductases; Intracellular; Sex steroid hormone
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/j.ejphar.2009.12.030

The cardiovascular effects of estrogen are mediated in part by augmenting the function of endothelial nitric oxide synthase. Endothelial nitric oxide synthase activity is dependent on many cofactors including Ca
2+. Hence, we investigated the effect of chronic 17 β-estradiol treatment on the intracellular Ca
2+ concentration and endothelial nitric oxide synthase protein expression in the human endothelial cell line, EA.hy926, using spectrofluorometry and Western blot, respectively. Inhibiting the sarco(endo)plasmic reticulum Ca
2+ ATPase with thapsigargin caused an increase in the intracellular Ca
2+ concentration, which was higher in chronically 17 β-estradiol-treated (1
μM, 24
h) cells loaded with Fura-2-acetoxymethyl ester compared to vehicle-treated cells, suggesting a higher endoplasmic reticulum Ca
2+ content in 17 β-estradiol-treated cells. An enhanced Ca
2+ influx pathway in chronically 17 β-estradiol-treated cells was also observed. In addition, 17 β-estradiol-treated cells expressed higher levels of endothelial nitric oxide synthase protein in comparison to vehicle-treated cells. The chronic effect of 17 β-estradiol on Ca
2+ homeostasis and endothelial nitric oxide synthase expression was attenuated with the nonselective estrogen receptor inhibitor, ICI 182,780 (10
μM, 7α, 17β-[9-[(4,4,5,5,5-Pentafluoropentyl)sulfinyl]nonyl] estra-1,3,5(10)-triene-3,17-diol). Furthermore, analysis of the thapsigargin-evoked Ca
2+ response in chronically 17 β-estradiol-treated estrogen receptor α-knockdown cells showed no significant difference in Ca
2+ response compared to vehicle-treated estrogen receptor α-knockdown cells, indicating that the regulation of Ca
2+ homeostasis by 17 β-estradiol is mediated through an estrogen receptor α-dependent pathway. These data revealed an estrogen receptor α-dependent modulation of Ca
2+ homeostasis accompanying the enhancement of endothelial nitric oxide synthase expression in 17 β-estradiol-treated human endothelial cells.