Valsartan inhibits angiotensin II-induced vascular smooth muscle cell apoptosis

Abstract

Objective To investigate the impacts of valsartan on cell apoptosis induced by angiotensin Ⅱ in vascular smooth muscle cells, and discuss whether the mechanism is relevant to AMP-Activated Protein Kinases. Methods Vascular smooth muscle cells (A7r5) were designated to 5 groups: ①control(DMSO) group, ②Angiotensin Ⅱ(Ang Ⅱ) 100 μmol/L group, ③Angiotensin Ⅱ 100 μmol/L+ valsartan 10 μmol/L group, ④Angiotensin Ⅱ 100 μmol/L+ valsartan 10 μmol/L+ compound C 1 μmol/L group, ⑤Angiotensin Ⅱ 100 μmol/L+ 5-Aminoimidazole-4earboxamide-ribo-nucle-oside(AICAR) 100 μmol/L group, after 24h incubation, the intracellular activity of Caspase 3 was measured by spectrophotometry, the cell apoptosis were enumerated by low cytometry, the intracellular AMP-Activated Protein Kinases (AMPK) phosphorylation and total expression quantity were examined by western blot, the intracellular reactive oxygen species (ROS) was measured by fluorescent probe DCFH-DA, the intracellular activity of total superoxide dismutase(SOD) was measured by WST-1 method, the intracellular activity of Malondialdehyde (MDA) was measured by TBA method. Two groups were compared by using Student t test. Differences among multiple groups were evaluated by ANOVA. Results Compared with control group, the cell apoptosis of Angiotensin Ⅱ group was increased[(45.46±15.40)% vs.(1.88±3.28)%, P=0.002], the synthesis of ROS was increased [(9.24±0.46)vs.(1.00±0.00), P<0.01], the activity of Caspase 3 was increased [(35.03±3.54)vs.(13.33±1.79), P<0.01], the activity of MDA was increased [(4.32±0.73)vs.(2.05±0.18), P<0.01)], the phosphorylation of AMPK was decreased, the activity of SOD was decreased [(90.29±14.73)vs.(136.02±18.82), P=0.001]; compared with Angiotensin Ⅱ group, the cell apoptosis of Angiotensin Ⅱ+ valsartan group and Angiotensin Ⅱ+ AICAR group were decreased[(24.91±8.46)% vs.(45.46±15.40)%, P=0.031]; [(27.90±4.39)% vs.(45.46±15.40)%, P=0.038], the synthesis of ROS was decreased[(2.37±0.05)vs.(9.24±0.46), P<0.01]; [(2.79±0.31)vs.(9.24±0.46), P<0.01], the activity of Caspase 3 was decreased [(18.08±2.69)vs.(35.03±3.54), P<0.01]; [(27.83±3.56)vs.(35.03±3.54), P=0.002], the activity of MDA were decreased [(3.25±0.55)vs.(4.32±0.73), P=0.017]; [(3.46±0.60)vs.(4.32±0.73), P=0.047], the phosphorylation of AMPK was increased, the activity of SOD was increased [(140.71±20.27)vs.(90.29±14.73), P<0.01]; [(116.73±17.96)vs.(90.29±14.73), P=0.029]; compared with Angiotensin Ⅱ+ valsarntan group, the cell apoptosis of Angiotensin Ⅱ+ valsartan+ compound C group was increased[(43.84±12.00)% vs.(24.91±8.46)%, P=0.043], the synthesis of ROS was increased [(4.64±0.15)vs.(2.37±0.05), P<0.01], the activity of Caspase 3 was increased[(25.64±3.52)vs. (18.08±2.69), P=0.011], the activity of MDA was increased[(5.12±0.92)vs.(3.25±0.55), P<0.01], the phosphorylation of AMPK was decreased, the activity of SOD was decreased [(99.48±16.59)vs.(90.29±14.73), P=0.002)]. Conclusions Valsartan could inhibit angiotensin Ⅱ-induced vascular smooth muscle cell apoptosis via activating AMPK, suppressing the synthesis of ROS and the activity of MDA, elevating the activity of SOD. Key words: Valsartan; Angiotensin Ⅱ; Vascular smooth muscle cell; Apoptosis; AMP-Activated Protein Kinases; Reactive oxygen species; Total superoxide dismutase; Malondialdehyde