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

ABSTRACT: 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 beta-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 beta-estradiol-treated (1muM, 24h) cells loaded with Fura-2-acetoxymethyl ester compared to vehicle-treated cells, suggesting a higher endoplasmic reticulum Ca(2+) content in 17 beta-estradiol-treated cells. An enhanced Ca(2+) influx pathway in chronically 17 beta-estradiol-treated cells was also observed. In addition, 17 beta-estradiol-treated cells expressed higher levels of endothelial nitric oxide synthase protein in comparison to vehicle-treated cells. The chronic effect of 17 beta-estradiol on Ca(2+) homeostasis and endothelial nitric oxide synthase expression was attenuated with the nonselective estrogen receptor inhibitor, ICI 182,780 (10muM, 7alpha, 17beta-[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 beta-estradiol-treated estrogen receptor alpha-knockdown cells showed no significant difference in Ca(2+) response compared to vehicle-treated estrogen receptor alpha-knockdown cells, indicating that the regulation of Ca(2+) homeostasis by 17 beta-estradiol is mediated through an estrogen receptor alpha-dependent pathway. These data revealed an estrogen receptor alpha-dependent modulation of Ca(2+) homeostasis accompanying the enhancement of endothelial nitric oxide synthase expression in 17 beta-estradiol-treated human endothelial cells.

SUBMITTER: Thor D 

PROVIDER: S-EPMC2822064 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature