Atorvastatin suppresses vascular hypersensitivity and remodeling induced by transient adventitial administration of lipopolysaccharide in rats.

BACKGROUND: The phenotypic transition of vascular smooth muscle cells (VSMCs) from a contractile to a proliferative state markedly affects the pathophysiology of cardiovascular diseases. The adventitial inflammation can promote neointimal formation and vascular remodeling. We used direct administration of lipopolysaccharide (LPS) into the periphery of the carotid artery to investigate the influence of transient adventitial inflammation on vascular remodeling and its potential mechanism. METHODS: Male 15-week-old Wistar rats were randomly assigned to four groups with six rats in each group. The rats of groups I and II were administered distilled water, and group III and IV were treated with fasudil and atorvastatin respectively. All treatments were given daily for 11 days. On day 8, the adventitia in group I was injected with 5 µL sterile saline, and the group II-IV were injected with 5 µL sterilized LPS. The carotid blood flow and femoral blood pressure were measured in vivo, and the thickness of vascular intima and middle layer was measured in vitro. Serum interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) were determined using enzyme-linked immunosorbent assay (ELISA) assay. And the Rho-associated coiled-coil-containing protein kinase 2 (ROCK2), myosin phosphatase target subunit 1 (MYPT1), myosin light chain (MLC), myocardin, SM-α actin or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected by western blot. The comparisons were made by one-way analysis of variance with Bonferroni's post hoc test. A value of P<0.05 was considered to represent a statistically significant difference. RESULTS: Transient adventitial inflammation induced by LPS caused no obvious change in basal blood flow, but did lead to vascular hypersensitivity to serotonin. Morphological examinations revealed that the medial layer was the only domain affected, and showed VSMC proliferation and rearrangement. LPS increased serum IL-6 and TNFα contents, ROCK2 expression and activity, and caused changes in the expression levels of some stereotypical VSMC genes. Similar to the Rho-kinase inhibitor fasudil, atorvastatin completely restored the morphological alterations, even increased blood flow. CONCLUSIONS: Our study confirms the beneficial effect of atorvastatin on the vascular system in terms of morphology and function.

[Effect of valsartan on vasoconstriction induced by the chronic injury of the adventitia in the rat collared carotid artery].

OBJECTIVE: Vasoconstriction and vascular hypersensitivity to serotonin were previously shown in animal models of adventitia injury. We investigated the contribution of angiotensin II (AngII)/AngII receptors and oxidative stress to vascular contractility and reactivity in this model. METHODS: Wistar Kyoto rats were divided into 3 groups: normal (n = 6, no any intervention, only for measuring the serum AngII concentration), vehicle (n = 12, collared), and valsartan (n = 12, collared + valsartan 30 mg×kg(-1)×d(-1)). After one week of treatment, adventitia injury was induced by positioning a silicone collar around the right carotid artery for one week. Blood flow and vascular reactivity to serotonin were determined one week after injury, the blood from left ventricle was taken to measure the serum AngII concentration by ELISA, and carotids were harvested for morphometry and Western blot analysis. RESULTS: Adventitia injury induced lumen cross-sectional area reduction (-44% vs. -5%), media diameter increase (62% vs. 10%), blood flow reduction [(2.79 ± 0.22) vs. (4.33 ± 0.84) ml/min] were significantly attenuated by valsartan. The increased vascular reactivity sensitivity to serotonin in vehicle group was also significantly reduced in valsartan group. Serum AngII concentration was significantly increased in vehicle group [(45.21 ± 4.52) pg/ml vs. (19.83 ± 0.5) pg/ml in normal rats, P = 0.0148] and the expression of AngII type 1 (AT(1)) receptor, AngII type 2 (AT(2)) receptor, as well as p22(phox) in collared arteries were significantly upregulated. Valsartan did not affect the AT(1) receptor expression but further increased serum AngII concentration [(89.73 ± 20.44) pg/ml vs. (45.21 ± 4.52) pg/ml, P = 0.001], and AT(2) receptor expression, while downregulated p22(phox) expressions. CONCLUSIONS: Collar-induced adventitia injury resulted in chronic vasoconstriction and vascular hypersensitivity to serotonin via increased serum AngII level, upregulated AngII receptors expression in the vascular well, and activated local oxidative stress. These changes could be blocked by valsartan suggesting a crucial role of AngII/AngII receptors on vascular contractility and reactivity changes in this model.

Effect of tongxinluo on vasoconstriction induced by the chronic injury of the adventitia in the rat carotid artery.

OBJECTIVE: Tongxinluo (TXL) is a traditional Chinese medicine that is developed on the meridian theory of traditional Chinese medicine, with the function of alleviating the angina. The present study was undertaken to explore the molecular mechanism of TXL in treating the pectoris angina through observing the effectiveness of TXL superfine powder on the vasoconstriction and the activation of RhoA/Rho-kinase pathway induced by the injury of the adventitia. METHODS: 36 male Wistar Kyoto rats were assigned to 3 treatments (n=12): vehicle, TXL (400 mg kg(-1) day(-1)) and fasudil (15 mg kg(-1) day(-1)). After 1 week of treatment, adventitia injury was induced by positioning a silicone collar around the right carotid artery for 1 week. Blood flow and vascular reactivity to serotonin were determined 1 week after injurying, the both sides of carotids were harvested for morphometry, Western blotting analysis and RT-PCR analysis. RESULTS: Adventitia injury leaded to histological changes of vasoconstriction with the lumen cross-sectional area of 44.7% (p<0.001) decreasing and the media diameter of 62.31% (p<0.001) increasing, accompanying by the reduction of the blood flow and the increase of vascular reactivity sensitivity to serotonin. Treatment with both TXL superfine powder and fasudil can prevent the development of vasoconstriction, improve the carotid blood flow and normalize the vascular hypersensitivity to serotonin. Adventitia injuring of the rat carotid increased the expression of Rho-kinase mRNA and p-MYPT1(Thr696) protein by 1.78-fold (p<0.05) and >2-fold respectively (p<0.05). TXL reduced the expression of Rho-kinase mRNA and p-MYPT1(Thr696) protein by 54.2% (p<0.05) and 57.1% (p<0.05) respectively in collared arteries. Fasudil restrained the p-MYPT1(Thr696) protein expression by 63.8% (p<0.05) in collared arteries, did not affect the collar-induced the increase of Rho-kinase mRNA expression (p>0.05). CONCLUSIONS: Treatment with TXL, similar to that with fasudil, can effectively prevent collar-induced vasoconstriction and vascular hyperreactivity to serotonin through inhibiting the RhoA/Rho-kinase pathway.