17??-Estradiol Increases Intracellular Calcium Concentration Through a Short-Term and Nongenomic Mechanism in Rat Vascular Endothelium in Culture

Abstract

17Beta-estradiol (E2) plays an important role in Ca2+ fluxes in several cell types. It has been proposed that some of its effects are of nongenomic origin E2 at vascular smooth muscle level can block calcium entry through L-type calcium channels, this mechanism cannot include vascular endothelial cells (VECs), in which increases in the intracellular calcium concentration ([Ca2+]i) are necessary to NO synthesis. We used male rat aorta ECs in culture loaded with fura-2 and a fluorescence imaging system to evaluate the short-term effects of E2 on [Ca2+]i kinetics. We explored the participation of the intracellular steroid receptor on the effects induced by E2, using tamoxifen (1 microM) and ICI 182,780 (10 microM). Our results showed that E2 (like bradykinin) induced an increase in [Ca2+]i. Such agonist-like effects showed a biphasic curve behavior. The 17beta-estradiol effects were not modified by the presence of the intracellular estradiol-receptor antagonist tamoxifen, but it is blocked in the presence of the ICI 182,780. The 17beta-estradiol effects were obtained even with restriction of steroid-free diffusion into cells (17beta-estradiol-bovine serum albumin). Phospholipase Cbeta activity is involved in these effects, because U-73122, a PLCbeta inhibitor, blocked E2 effects. All E2 effects were of rapid onset (milliseconds), exerted at the membrane level, and of rapid offset. We conclude that estradiol can influence the endothelium physiologic responses through effects of nongenomic origin.

Distribution and characterization of estrogen receptor G protein-coupled receptor 30 in the rat central nervous system

“…Estradiol-BSA (E2-BSA) has been shown to elevate [Ca 2C ] i through non-genomic ERs in several cell models; for example, E2-BSA elevates [Ca 2C ] i in gonadotropin-releasing hormone-1 neurons (Temple & Wray 2005), human granulocytes (Stefano et al 2000a), and cultured human pre-osteoclastic cells (Fiorelli et al 1996). Fast calcium mobilization by E2-BSA has also been reported in rat aorta endothelial cells (Rubio-Gayosso et al 2000), as well as in thoracic and human arterial endothelia (Stefano et al 2000b). The observation that G-1, the GPR30 selective agonist (Bologa et al 2006), rapidly elevates [Ca 2C ] i in hypothalamic cells is consistent with a non-nuclear effect of estrogen.…”

Acute effects of 17β-estradiol on femoral veins from adult gonadally intact and ovariectomized female pigs

“…Estrogen causes releases NO from arterial endothelial cells (11,44,47,60). Venous endothelial cells also synthesize and release NO, although in lower levels compared with arteries (38).…”

Effects of estradiol on phenylephrine contractility associated with intracellular calcium release in rat aorta

“…To assess estradiol direct effects on the sarcoplasmic reticulum, we added caffeine (an intracellular Ca 2ϩ releaser; 10 mM) (1,20) instead of phenylephrine, to contract aortic rings incubated in Ca 2ϩ -free solution. It has been shown that cyclopiazonic acid induces capacitative Ca 2ϩ entry through non-L-type Ca 2ϩ channels in rat aorta (16); hence, the ability of estradiol to interfere with such Ca 2ϩ entry was assessed by studying the effects of the hormone (pretreatment for 5 min) on the contractile response to cyclopiazonic acid (10 M) of aortic rings incubated in Ca 2ϩ -containing solution.…”

“…We evaluated changes in the intracellular Ca phenylephrine or the entry of extracellular Ca 2ϩ dependent on the depletion of the intracellular Ca 2ϩ stores. The fura-2 fluorescence response to the intracellular Ca 2ϩ concentration was calibrated as previously described (20).…”