Simvastatin Ameliorates Rat Cerebrovascular Remodeling During Hypertension via Inhibition of Volume-Regulated Chloride Channel

Abstract

Abstract-Statins have pleiotropic actions against the development of vascular remodeling and the incidence of ischemic stroke. Although previous studies have suggested that posttranslational modification of several proteins, such as Rho by mevalonate-derived isoprene groups, geranylgeranyl pyrophosphate or farnesyl pyrophosphate, underlie the pleiotropic effects of statins, the detailed mechanisms remain elusive. Recent growing evidence demonstrated that ClC-3 volume-regulated chloride channel plays an important role in cell proliferation, and the activity of this channel is increased in basilar smooth muscle cells from a hypertensive rat. We hypothesized that inhibition of volume-regulated chloride channel may contribute to the beneficial effects of statins on cerebrovascular remodeling during hypertension. Our study here demonstrated that simvastatin ameliorated hypertension-caused cerebrovascular remodeling. In rat basilar smooth muscle cells, simvastatin inhibited cell proliferation and activation of volume-regulated chloride channel, and these effects of simvastatin were abolished by pretreatment with mevalonate or geranylgeranyl pyrophosphate. In addition, Rho A inhibitor C3 exoenzyme and Rho kinase inhibitor Y-27632 both reduced cell proliferation and activation of volume-regulated chloride channel. Moreover, ClC-3 overexpression decreased the suppressive effect of simvastatin on cell proliferation and increased estimated IC 50 of simvastatin on endothelin 1-and hypo-osmolarityinduced cell proliferation from 3.40Ϯ0.08 and 3.50Ϯ0.10 mol/L to 5.30Ϯ0.70 and 5.60Ϯ0.70 mol/L, respectively (PϽ0.01; nϭ6). Furthermore, the expression of ClC-3 was increased in basilar artery during hypertension, and simvastatin normalized the upregulation of ClC-3. Our data suggested that simvastatin ameliorates cerebrovascular remodeling in the hypertensive rat through inhibition of vascular smooth muscle cell proliferation by suppression of volume-regulated chloride channel. (Hypertension. 2010;56:445-452.)Key Words: volume-regulated chloride channel Ⅲ simvastatin Ⅲ hypertension Ⅲ cerebrovascular remodeling Ⅲ basilar smooth muscle cell C erebral arterioles undergo remodeling of the vascular walls during chronic hypertension, which is caused by the coordination of vascular smooth muscle cell (SMC) proliferation and migration, endothelial cell dysfunction, inflammation, and fibrosis. [1][2][3] It has been generally accepted that vascular remodeling is an important determinant of increased risk of stroke that accompanies chronic hypertension. 4,5 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are extensively used in clinic to treat hypercholesterolemia by inhibiting cholesterol biosynthesis. A number of large clinical trials and animal experiments have established that statins are available to reduce the mortality and morbidity of cardiovascular events, such as coronary artery disease and stroke. 6 -9 These beneficial effects of statins cannot be merely attributed to their lipid-lowering property. 8,10 Recen...

Integrin β3 mediates cerebrovascular remodelling through Src/ClC‐3 volume‐regulated Cl− channel signalling pathway

“…Our previous study demonstrated that the expression of ClC-3 in basilar arteries was increased gradually with the development of cerebrovascular remodelling induced by hypertension (Liu et al, 2010), and a deficiency of ClC-3 attenuated cerebrovascular remodelling in DOCA-salt hypertension (Zheng et al, 2013). In the present study we showed that integrin β3 expression was positively correlated with ClC-3 expression in basilar arteries from 2K2C hypertensive rats, r = 0.641 (see Supporting Information Figure S3b).…”

“…Our previous studies showed that smooth muscle α-actin staining was increased time-dependently in basilar arteries from 2K2C hypertensive rats. The mean values of medial cross-sectional area (CSA) increased in the hypertensive group after 4 weeks post-operatively compared with those in corresponding control groups (Liu et al, 2010). The present study showed that integrin β3 expression was positively correlated with the medial CSA of the basilar artery from 2K2C hypertensive rats, r = 0.6025 ( Figure 1D).…”

“…We previously found that ClC-3 channel activity and protein expression were significantly increased in BASMCs from 2K2C hypertensive rats and these increases paralleled the severity of cerebrovascular remodelling (Shi et al, 2007). Moreover, simvastatin ameliorated hypertension-induced cerebrovascular remodelling by inhibiting the proliferation of cerebrovascular smooth muscle cell and suppressing ClC-3 chloride channel activity (Liu et al, 2010). Furthermore, ClC-3 knockout attenuated the cerebrovascular remodelling that occurs in DOCA-salt hypertensive mice (Zheng et al, 2013).…”

“…The rat brain was carefully removed and sections (8 μm) were prepared from freshly frozen rat basilar arteries as previously described (Shi et al, 2007;Liu et al, 2010) 2 . Randomly selected 3 sections in each group were pretreated with the solution of 3% hydrogen peroxide and methanol at the ratio of 1:50 for 30 min at room temperature, and then blocked with 5% BSA in PBS for 30 min.…”

“…Our previous studies demonstrated that ClC-3 (see Alexander et al, 2013) is responsible for volume-regulated Cl − currents in VSMCs (Zhou et al, 2005) and the activity of the volumeregulated ClC-3 Cl − channel displayed a pressure-dependent increase in basilar artery smooth muscle cells (BASMCs) from 2-kidney 2-clip (2K2C) hypertensive rats, and the size of this increase paralleled the severity of cerebrovascular remodelling (Shi et al, 2007). Also, a deficiency of ClC-3 channels attenuated cerebrovascular remodelling during hypertension (Liu et al, 2010;Zheng et al, 2013).…”