Angiotensin II promotes iron accumulation and depresses PGI₂and NO synthesis in endothelial cells: effects of losartan and propranolol analogs

Abstract

Angiotensin may promote endothelial dysfunction through iron accumulation. To research this, bovine endothelial cells (ECs) were incubated with iron (30 μmol·L−1) with or without angiotensin II (100 nmol·L−1). After incubation for 6 h, it was observed that the addition of angiotensin enhanced EC iron accumulation by 5.1-fold compared with a 1.8-fold increase for cells incubated with iron only. This enhanced iron uptake was attenuated by losartan (100 nmol·L−1), D-propranolol (10 μmol·L−1), 4-HO-propranolol (5 μmol·L−1), and methylamine, but not by vitamin E or atenolol. After 6 h of incubation, angiotensin plus iron provoked intracellular oxidant formation (2′7′-dichlorofluorescein diacetate (DCF-DA) fluorescence) and elevated oxidized glutathione; significant loss of cell viability occurred at 48 h. Stimulated prostacyclin release decreased by 38% (6 h) and NO synthesis was reduced by 41% (24 h). Both oxidative events and functional impairment were substantially attenuated by losartan or D-propranolol. It is concluded that angiotensin promoted non-transferrin-bound iron uptake via AT-1 receptor activation, leading to EC oxidative functional impairment. The protective effects of D-propranolol and 4-HO-propranolol may be related to their lysosomotropic properties.

Iron Overload Damages the Endothelial Mitochondria via the ROS/ADMA/DDAHII/eNOS/NO Pathway

“…There is growing evidence that iron overload-induced excessive ROS generation triggers subsequent pathophysiological changes [16–18, 20–22]. In this study, we found that in HUVECs that were treated with iron-D for 48 hours, the intracellular and mitochondrial ROS generation significantly increased (see Figure 5(a)), thereby indicating that increased ROS was responsible for cell damage.…”

Mg supplementation protects against ritonavir-mediated endothelial oxidative stress and hepatic eNOS downregulation

“…To examine the cytotoxic effects of ritonavir (RTV) and Mg, we used the well-established MTT assay [23,32]. As illustrated by Fig 1, RTV concentration-dependently caused moderate but significant losses of cell viability which were −13%, −19%, −24% and −41% respectively from 5 to 30 µM of RTV (Fig 1A).…”

“…Cells were grown in DMEM/F12, plus 15% fetal bovine serum, 0.02mg/ml endothelial cell growth supplement, 0.05mg/ml heparin sodium salt, 0.01ml/ml complete media with Penicillin-Streptomycin in 37°, 5% CO 2 incubator. Cell viability following exposure to different combination of drug treatments with normal (0.8mM) or high (2mM) MgSO 4 , was measured by using the MTT method [23]. BAECs at exponential phase between passages 3–6 were seeded at 10 4 cells/wells in 24-well plates until it reached 85–95% confluence.…”

“…Total NO products (nitrite plus nitrate) released over 24 hours in the cell medium was determined by the Griess reagent method using E. coli nitrate reductase to convert nitrate to nitrite as described [23,24]. To measure rat plasma nitrite levels, the method of Nussler et al [27] using fluorometric measurement of nitrite by 2,3-diaminonaphthalene (DAN) was slightly modified as following.…”

The Protective Effect of Bafilomycin A1 Against Cobalt Nanoparticle-Induced Cytotoxicity and Aseptic Inflammation in Macrophages In Vitro

“…The T-GSH/GSSG levels and enzymatic activities of T-SOD, CAT, and GPx were detected according to the manufacturer's protocol using the corresponding diagnostic kits. Total GSH/GSSG levels were determined enzymatically by the 5, 5′-dithiobis (2-nitrobenzoic acid)-glutathione reductase method as described by Mak et al [21,22]. T-SOD activity was assayed using the xanthine/xanthine oxidase method based on the production of O 2− anions [23].…”