气体信使硫化氢在大鼠肾血管性高血压中的调节作用

目的探讨硫化氢体系在肾血管性高血压形成及发展中的变化和作用。方法成年的雄性Wistar大鼠28只,随机分为对照组7只、双肾一夹组(two-kidney,one-clip,2KIC组)7只、2KIC+硫氢化钠(硫氢化钠为外源性硫化氢供者)组8只、假手术组6只,其中2KIC+硫氢化钠组每天腹腔注射硫氢化钠(56μmol/kg),对照组、2KIC组及假手术组注射相同剂量的生理盐水。相同条件饲养4周,4周后处死,检测血浆硫化氢水平,双肾硫化氢合酶的活性,血管紧张素Ⅱ,左心与全心重量比,光学显微镜下观察肾的显微结构变化。结果术后4周,2KIC组尾动脉压显著高于假手术组及2KIC+硫氢化钠组;2KIC组的血管紧张素Ⅱ显著高于假手术组和对照组;左心室与全心重量比值2KIC组高于对照组和假手术组;肾内硫化氢合酶的活性及血浆中硫化氢的含量2KIC组显著低于假手术组及对照组,2KIC+硫氢化钠组高于2KIC组。结论肾血管性高血压大鼠硫化氢体系受到严重抑制,可能是肾性高血压形成的重要因素,外源性的给予硫化氢供者有助于缓解高血压的形成。     

自发性高血压大鼠脑出血后炎症反应与Th17细胞的相关性

目的探讨自发性高血压大鼠(SHR)脑出血后炎症反应与Th17细胞的相关性。方法 SHR随机分为正常对照组,假手术组和模型组各5只。胶原酶大脑尾状核注射制备大鼠自发性高血压脑出血(HICH)模型。出血后48 h,冰上取脑。流式细胞仪检测脑组织中Th17细胞占CD4+T细胞的百分比;酶联免疫吸附(ELISA)方法检测脑组织上清中白细胞介素(IL)-6和肿瘤坏死因子(TNF)-α水平。结果与正常对照组和假手术组相比,模型组脑组织中Th17细胞数量明显增加,同时IL-6和TNF-α分泌水平明显升高。结论脑出血急性期炎症反应的诱导和发生与Th17细胞的参与密切相关,Th17细胞促进了脑出血后的病理进程;可能部分通过诱导炎性细胞因子IL-6和TNF-α分泌增加实现的。     

硫化氢与高血压

硫化氢(hydrogen sulfide,H2S)是第三个被发现的气体信号分子。研究发现高血压患者的血浆H2S水平显著降低,而H2S水平与高血压的各项危险因素(如肥胖、胰岛素抵抗、脂代谢紊乱等)及心血管、脑、肾等靶器官损害的发生密切相关,这可能由于内源性H2S可通过直接舒张血管,抑制平滑肌细胞增殖,减少细胞外基质,减轻血管的炎症反应,促进血管新生,抑制肾素的激活等作用来参与高血压的发病及病理生理过程。预期H2S有可能成为一种监测标志,甚至是降压药物,应用于高血压病的临床诊断和治疗。     

硫化氢对低氧性肺动脉高压大鼠细胞因子的调节作用

目的探讨硫化氢对低氧性肺动脉高压大鼠细胞因子的调节作用。方法将Wistar大鼠22只随机分为3组。对照组(8只),低氧组(7只),低氧+硫氢化钠(NaHS)组(7只),测定3组大鼠肺动脉平均压(mPAP),观测肺血管结构变化,并用免疫组织化学方法研究α-平滑肌肌动蛋白(-αSM-actin)、弹力蛋白、转化生长因子β(TGF-β)和结缔组织生长因子(CTGF)在肺动脉平滑肌细胞的表达含量。结果低氧组的mPAP明显高于对照组和低氧+NaHS组;低氧组肌型动脉、部分肌型动脉百分比明显高于对照组和低氧+NaHS组,非肌型动脉百分比明显低于对照组和低氧+NaHS组;低氧组肺中、小型肺动脉平滑肌细胞-αSM-actin、弹力蛋白和TGF-β表达含量分别明显高于对照组和低氧+NaHS组;对照组、低氧+NaHS组以及低氧组肺中、小型肺动脉平滑肌细胞CTGF表达含量依次增高,但3组之间无显著差异。结论硫化氢可能通过调节低氧性肺动脉高压大鼠肺小血管肌性动脉TGF-β的表达,进而抑制细胞外基质成分之一的弹力蛋白合成,参与低氧性肺动脉高压的形成。     

福辛普利对自发性高血压大鼠模型血压水平及炎症反应、心血管重构的影响

目的 研究福辛普利对自发性高血压大鼠血压水平、炎症反应及心血管重构的影响。方法 选择自发性高血压大鼠作为实验动物并分为对照组和ACEI组。对照组给予生理盐水,ACEI组给予福辛普利干预。干预前后分别测定尾动脉收缩压,干预后测定心脏组织中炎性因子、重构分子的含量以及肾脏组织中炎性因子的含量。结果[结果部分应列举主要数据,并修改英文摘要] 干预后2周、4周、6周、8周时,ACEI组大鼠尾动脉收缩压呈逐步降低趋势,对照组大鼠尾动脉收缩压无明显变化,ACEI组大鼠尾动脉收缩压显著低于对照组;干预后8周,ACEI组大鼠心脏组织中NF-κB（3.28±0.64 vs 6.61±0.93）ng/mg、IL-1β（1.02±0.17 vs 1.92±0.28）ng/mg、IL-6（0.74±0.11 vs 1.87±0.30）ng/mg、TNF-α（1.46±0.22 vs 3.42±0.57）ng/mg、CTGF（152.52±25.25 vs 353.68±51.24）pg/mg、α-actinin（1.86±0.26 vs 4.25±0.67）ng/mg、MMP-9（177.53±23.15 vs 353.64±46.79）pg/mg的蛋白含量均显著低于对照组,大鼠肾脏组织中NF-κB（2.24±0.35 vs 5.58±0.79）ng/mg、IL-1β（1.42±0.19 vs 3.20±0.56）ng/mg、IL-6（1.18±0.22 vs 2.78±0.35）ng/mg、TNF-α（0.51±0.62 vs 1.24±0.19）ng/mg的蛋白含量均显著低于对照组。结论 福辛普利用于自发性高血压大鼠能够降低血压并抑制炎症反应和心血管重构。     

有氧运动对自发性高血压大鼠心脏炎症的影响及机制的探讨

目的 探讨有氧运动对自发性高血压大鼠（SHR）心脏炎症的调节及其机制。方法 8周龄雄性SHR大鼠和正常血压对照WKY大鼠各16只,将SHR大鼠随机分为SHR安静组和SHR运动组;将WKY大鼠随机分为WKY安静组和WKY运动组,每组8只。其中运动组大鼠进行8周无负重游泳运动。采用超声心动仪检测心脏功能,用ELISA试剂盒检测心脏炎症因子TNF-α和IL-1β的含量,Western blot法检测心脏叉头框蛋白1（FoxO1）、p65 NF-κB、磷酸化Akt（p-Akt）和总Akt（t-Akt）的表达。结果 与WKY安静组大鼠相比,SHR安静组大鼠左心室p65 NF-κB的表达以及炎症因子TNF-α、IL-1β的含量及FoxO1表达明显升高（P<0.05,P<0.01）,p-Akt的水平下降（P<0.05）;与SHR安静组相比,8周有氧运动能够增强SHR大鼠心脏功能,降低p65 NF-κB的表达以及炎症因子TNF-α和IL-1β的含量（P<0.05）,同时降低FoxO1表达（P<0.05）,提高p-Akt的水平（P<0.05）。8周有氧运动同样能够降低WKY大鼠心脏FoxO1表达（P<0.05）,提高p-Akt的水平（P<0.05）。结论 8周无负重游泳运动能够降低SHR大鼠心脏炎症因子TNF-α和IL-1β的含量,其可能与加强Akt磷酸化水平和下调FoxO1表达有关,确切机制有待进一步研究。     

Apelin-13对自发性高血压大鼠的降压调节作用的研究

目的:探讨apelin-13对自发性高血压大鼠(spontaneously hypertensive rats,SHR)的降压作用及其相关的血压调节机制。方法:将16只正常Wistar大鼠和16只SHR各平均分为2组,即生理盐水对照组和apelin-13实验组。采用股静脉插管给药,并检测血压和心率的变化。结果:静脉给予15 mg/kg apelin-13后1 min,可使正常Wistar大鼠的收缩压和舒张压分别从(120±7)mmHg和(90±11)mmHg降低至(96±8)mmHg和(81±8)mmHg(分别降低20%和10%);使其心率从(377±26)次/min升高为(421±36)次/min(升高了1.8%),而在相同条件下,可使SHR的收缩压和舒张压分别从(220±15)mmHg和(170±13)mmHg降低至(145±16)mmHg和(117±10)mmHg(分别降低了47%和15%);使SHR的心率从(398±31)次/min升高为(449±42)次/min(升高了2.1%)。结论:与正常Wistar大鼠相比较,apelin-13对SHR具有明显的降压作用。     

复方丹参滴丸对自发性高血压大鼠血管重构的影响

目的 探讨复方丹参滴丸(DSP)对自发性高血压大鼠(SHR)血管重构的影响.方法 将32只8周龄雄性SHR随机分为4组,DSP小剂量组、DSP大剂量组、福辛普利组、SHRc组.另选8周龄雄性Wistar大鼠为正常对照组.5组分别用灌胃法给药或给蒸馏水8周,测定大鼠尾动脉收缩压、胸主动脉与肠系膜动脉中层壁厚(M)、管腔内径(L)及二者的比值(M/L).结果 与Wistar组比,SHRc组主动脉中层壁[Wistar组:(85±10) μm比SHRc组(120±7) μm]与肠系膜动脉中层壁[Wistar组:(61±8) μm比SHR模型组(84±8) μm]显著增厚(P<0.05),中层壁厚与管腔内径比值(M /L)也显著增大(P<0.05);与SHRc组比,DSP大剂量组[肠系膜动脉M:(65±5) μm;主动脉M:(94±7) μm]、小剂量组[肠系膜动脉M:(70±3) μm;主动脉M:(97±9) μm]与福辛普利组[肠系膜动脉M:(64±7) μm;主动脉M:(93±6) μm]SHR主动脉与肠系膜动脉的M及M /L均明显减轻(P<0.05),而各治疗组间无统计学意义(P>0.05).结论 复方丹参滴丸可抑制SHR的血管壁重构.     

氯沙坦对自发性高血压大鼠阻力血管结构的影响

目的探讨氯沙坦（Losartan）对自发性高血压大鼠（SHR）阻力血管结构的影响,并观察在高血压血管壁增厚的过程中血管紧张素Ⅱ(AngⅡ)所起的作用。 方法采用6周龄雄性SHR20只,随机分为Losartan治疗组（SHRlos）和对照组（SHR）。另选同系雄性6周龄WKY鼠10只作为正常对照组。6周龄SHRlos给予Losartan30mg/kg/d,溶于饮水灌胃治疗17周。颈动脉插管,心电血流动力学监护仪测定动脉收缩压,应用计算机图象分析,计算血管壁腔面积比,用光镜和透射电镜观察SHR肠系膜动脉三级分支结构的变化;血浆放免法测肾素活性和AngⅡ含量。 结果（1）动脉收缩压（SBP）治疗结束后,SHR     

盐酸埃他卡林对自发性高血压大鼠血浆生化指标及炎症相关因子的影响

目的观察盐酸埃他卡林(Ipt)对自发性高血压大鼠血浆生化指标及炎症相关因子的影响。方法SHR大鼠在2月龄进入实验,体重200～250g,雌雄不限,随机分为6组:SHR对照组5只,WKY对照组5只,Ipt 3个剂量1、3、9mg·kg~(-1)·d~(-1)治疗组各6只,苯那普利(Ben)6mg·kg~(-1)·d~(-1)治疗组6只。灌胃给药每天1次,8wk后处死动物,检测血浆Glu,Tcho,TG,LDL-c,HDL-c, BUN,Cr,UA,Ins,hs-CRP,IL-6,TNF-α等指标。结果SHR大鼠对照组较WKY大鼠对照组,血浆BUN,Cr,UA显著增高(P＜0．05),血糖、血脂无显著差异(P＞0．05),经Ipt 1、3、9mg·kg~(-1)·d~(-1)及Ben 6mg·kg~(-1)·d~(-1)治疗后,血浆BUN,Cr,UA降至正常;SHR大鼠与WKY大鼠对照组比较,血浆Ins、hs-CRP、TNF-α、IL-6显著增高,Ipt 3、9mg·kg~(-1)·d~(-1)剂量治疗后,较SHR对照组大鼠均显著降低(P＜0．05),1mg·kg~(-1)·d~(-1)剂量及Ben治疗后,无明显改变(P＞0．05)。结论盐酸埃他卡林及苯那普利均能有效地改善肾功能,盐酸埃他卡林3、9mg·kg~(-1)·d~(-1)剂量治疗后能降低血浆Ins、TNF-α、IL-6、hs-CRP等炎症相关因子。     

Hypotensive and bradycardic effects of centrally administered vasopressin in stroke-prone spontaneously hypertensive rats

The cardiovascular effects of centrally administered arginine vasopressin were studied in stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats. Arginine vasopressin was infused intracerebroventricularly into conscious rats at a rate of 2 pg/kg/min (4.6 microliter/hr) for 21 hours, and blood pressure and heart rate were monitored. Arginine vasopressin caused transient hypertension and tachycardia in Wistar-Kyoto rats, whereas it induced delayed hypotension and bradycardia in stroke-prone spontaneously hypertensive rats. The effects on the latter lasted for 24 to 72 hours after cessation of the infusion. Intravenous administration of arginine vasopressin at a rate of 2 pg/kg/min did not cause any change in blood pressure and heart rate in these rats. These results suggest that arginine vasopressin acts centrally to depress cardiovascular activities, at least in stroke-prone spontaneously hypertensive rats.     

Hypotensive responses to centrally administered taurine in DOCA-salt hypertensive and spontaneously hypertensive rats

The present study was designed to investigate the short-term effects of intracerebroventricularly-administered taurine in DOCA-salt hypertensive (DOCA), spontaneously hypertensive (SHR) and their respective normotensive control rats anesthetized with urethane. Blood pressure, heart rate and sympathetic nerve activity were consistently decreased following the injection of taurine 150 micrograms per rat in hypertensive rats as well as in normotensive controls of the two groups. Percent changes from the baselines in blood pressure, heart rate and sympathetic nerve activity were significantly larger in DOCA-salt hypertensive rats than those in sham operated rats. In contrast, percent changes in blood pressure and sympathetic nerve activity were not significantly different between spontaneously hypertensive rats and normotensive wistar kyoto rats. These result show that the responses of blood pressure, heart rate and sympathetic nerve activity to intracerebroventricular taurine are different between spontaneously hypertensive rats and DOCA-salt hypertensive rats. It appears that augmented vasodepressor responses to taurine in DOCA-salt hypertensive rats, as compared to spontaneously hypertensive rats, are due to enhanced inhibition of the sympathetic outflow.     

Death-associated protein kinase 3 mediates vascular inflammation and development of hypertension in spontaneously hypertensive rats

Death-associated protein kinase (DAPK) is a Ca(2+)/calmodulin-regulated serine/threonine kinase that mediates cell death. Our recent study demonstrated that DAPK3 protein increases in the mesenteric artery from spontaneously hypertensive rats compared with Wistar Kyoto rats. Pathogenesis of hypertension is modulated at least in part by vascular inflammation. We examined whether DAPK3 mediates vascular inflammatory responses and development of hypertension. In rat mesenteric arterial smooth muscle cells, small interfering RNA against DAPK3 inhibited vascular cell adhesion molecule 1 expression and monocyte adhesion induced by tumor necrosis factor-α. DAPK3 small interfering RNA inhibited phosphorylation of c-Jun amino-terminal kinase, p38, and Akt, as well as reactive oxygen species (ROS) production induced by tumor necrosis factor-α. In human umbilical vein endothelial cells, expressions of vascular cell adhesion molecule 1, endothelial selectin, and cyclooxygenase 2, as well as ROS production induced by tumor necrosis factor-α, were inhibited by DAPK inhibitor. In vivo, blood pressure, ROS production, inflammatory molecule expression (vascular cell adhesion molecule 1 and endothelial selectin), and hypertrophy in isolated mesenteric artery were elevated in spontaneously hypertensive rats (10 weeks old), which were prevented by long-term treatment with a DAPK inhibitor (500 μg/kg per day for 6 weeks). In isolated mesenteric artery, the increased angiotensin II-induced contraction and the impaired acetylcholine-induced endothelium-dependent relaxation in spontaneously hypertensive rats were reversed by a DAPK inhibitor. The present results for the first time demonstrated in cultured smooth muscle cells and endothelial cells that DAPK3 mediates tumor necrosis factor-induced inflammatory responses via ROS-dependent mechanisms. It is also suggested that DAPK3 mediates the development of hypertension in spontaneously hypertensive rats likely via ROS-dependent inflammation, hypertrophy, and hypercontractility.     

Neurotransmitter release and vascular reactivity in spontaneously hypertensive rats

This study was designed to investigate neurotransmitter release during the sympathetic nerve stimulation of perfused mesenteric arterial beds of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) at young and adult ages. The role of Ca in neurotransmitter release and vascular responsiveness was also examined by using a Ca-antagonist (verapamil). Pressor responses to electrical nerve stimulation and exogenous noradrenaline were greater in SHR than in WKY. Noradrenaline overflow by electrical nerve stimulation from mesenteric arterial beds was also significantly greater in young SHR than age-matched WKY. However, in adult SHR, the noradrenaline overflow was reduced compared with WKY. After verapamil infusion (5.0 X 10(-7)M approximately 2.5 X 10(-6)M), suppression of the pressor responses and noradrenaline overflow evoked by electrical nerve stimulation was greater in SHR than in WKY at both ages. The pressor responses to exogenous noradrenaline were also inhibited by verapamil more in young SHR than in young WKY. In adult SHR, the inhibition was similar to age-matched WKY. These results suggest that noradrenaline release from sympathetic nerve endings in SHR increase at a young age and decreases in adults, and depends at least partly on Ca-influx at both ages as dose vasoconstrictor reactivity. Therefore, Ca-dependency in SHR at both pre- and post-synaptic sites of neurotransmission may contribute to the pathogenesis of hypertension.     

Ghrelin inhibits vascular superoxide production in spontaneously hypertensive rats

BACKGROUND: Ghrelin is a novel peptide involved in the control of appetite, but its role in vascular pathologies remains to be elucidated. Ghrelin was shown to decrease blood pressure (BP) and improve endothelial function. Its plasma levels are correlated with BP in humans. Mechanisms of these effects are unknown. Because oxidative stress and increased superoxide production by NAD(P)H oxidases (Nox) are critical in the pathogenesis of hypertension, we aimed to study the effects of ghrelin on vascular superoxide production and NAD(P)H oxidase activity in spontaneously hypertensive rats (SHR). METHODS: Aortic superoxide production and NAD(P)H oxidase activity were measured using lucigenin (5 micromol/L) chemiluminescence. Aortas from Wistar-Kyoto rats (WKY) were used as control. Direct superoxide scavenging properties of ghrelin were tested using xanthine-xanthine oxidase system. RESULTS: Both basal superoxide production and vascular NADPH oxidase activity were significantly higher in aortas from SHR, than from WKY. Preincubation of aortic segments from SHR or WKY with ghrelin caused concentration-dependent (from 50 pg/mL to 5 ng/mL) decrease of basal superoxide production. Vascular NAD(P)H oxidase activity was inhibited by ghrelin, abolishing the difference between SHR and basal WKY. Ghrelin did not affect superoxide release from the in vitro xanthine-xanthine oxidase system, indicating lack of direct superoxide scavenging properties or inhibitory effects on xanthine oxidase in vitro. Nitric oxide synthase (NOS) inhibition, using N(omega)-nitro-L-arginine methyl ester (L-NAME), partially blunted the effects of ghrelin on NADPH oxidase activity indicating potential role of nitric oxide. CONCLUSIONS: Ghrelin inhibits vascular oxidative stress in SHR. This effect is likely related to the inhibition of vascular NAD(P)H oxidases.     

Lovastatin reduces renal vascular reactivity in spontaneously hypertensive rats

We have reported that lovastatin attenuates the development of hypertension in spontaneously hypertensive rats (SHR). The fall in arterial pressure is associated with an elevation in renal medullary blood flow, normalization of the pressure-natriuresis relationship, and diminished hypertrophy of renal arterioles. However, the mechanism by which lovastatin alters renal vascular tone is unknown. The present study examined the effects of lovastatin on renal vascular tone and the expression of G proteins. Four-week–old SHR were chronically treated with lovastatin (20 mg/kg/day) or vehicle by gavage for 4 weeks. At the end of the study, mean arterial pressure averaged 131 ± 4 (n = 5) and 160 ± 4 mm Hg (n = 6) in lovastatin- and vehicle-treated SHR, respectively. Renal arterioles isolated from lovastatin-treated SHR were significantly less responsive to norepinephrine and vasopressin than those obtained from vehicle-treated rats (ED₅₀: 5.0 v 1.8 × 10⁻⁷ mol/L for norepinephrine, and 8.0 v 5.2 × 10⁻¹⁰ mol/L for vasopressin). The fall in renal vascular reactivity in lovastatin-treated SHR was associated with reduced levels of ras and rho proteins in renal arterioles, whereas the expressions of heterotrimeric G proteins (G_s, G_q, G_i) were similar in renal arterioles from vehicle- and lovastatin-treated SHR. Overnight culture of renal arterioles with media containing lovastatin also diminished the expression of ras and rho proteins and the response to vasoconstrictors. These findings indicate that lovastatin diminishes the response to vasoconstrictors and the expression of small G proteins in the renal vasculature of SHR and suggest that a fall in the levels of ras and rho proteins in these vessels may contribute to the antihypertensive effects of lovastatin.     

The effects of Xuezhikang on vascular remodeling and aortic fibers in spontaneously hypertensive rats

Background Xuezhikang is a traditional Chinese medicine for the therapy of patients with cardiovascular diseases. However, the effect of Xuezhikang on vascular remodeling and aortic fibers in spontaneously hypertensive rats remains unclear. Methods Thirty spontaneously hypertensive rats(SHRs) aged 8 weeks were randomized into three groups: SHRs control group(SHRs group, n = 10), group treated with low dose Xuezhikang(XZK-L,20 mg/kg/d, n = 10) and group treated with high dose Xuezhikang(XZK-H, 200 mg/kg/d, n = 10). The normal group was comprised of ten Wistar-Kyoto(WKY) rats of the same age. While under pentobarbital anesthesia, in vivo aortic stiffness was determined by a pulse wave velocity(PWV) technique and measured locally in the descending thoracic aorta by Doppler ultrasound echocardiography. Fixed tissues were sectioned and stained with hematoxylin and eosin, masson trichrome, aldehyde-fuchsin and Gordon-Sweets stain. Results The PWV, thicknesses of the aortic wall, wall-to-lumen(W/L) ratio, elastic fibers thicknesses and collagen volume fraction were measured. XZK-L and XZK-H groups were observed to be significantly greater than those in the normal group(P 0.01). The levels of PWV, W/L ratio and collagen fibers were observed to be significantly reduced in the XZK-H group when compared with the control group(P 0.05). There was no significance in reticular fiber distributing between the XZK-treated group and SHR group. The reticular fibers in SHR rats were obviously more than those of WKY rats. Conclusion The hypertensive vascular remodeling is associated with changes of elastic fibers and collagen and reticular fibers. Xuezhikang improves hypertensive vascular remodeling by repairing the elastic fibers and inhibiting the levels of collagen.     

Differential effects of losartan and doxazosin on vascular function in senescent spontaneously hypertensive rats

We evaluated the effects of treatment for 12 weeks with 10 mg/kg/day of either losartan or doxazosin on vascular function in senescent spontaneous hypertensive rats (SHR). Both doxazosin and losartan reduced blood pressure, although the former was more effective. In contrast, both drugs reduced relative aortic weight and increased plasma nitrates to a similar extent. Losartan, but not doxazosin, increased the magnitude of the response to acetylcholine (10⁻⁹ to 10⁻⁵ mol/L). Both treatments increased relaxations to sodium nitroprusside (10⁻¹⁰ to 10⁻⁶ mol/L). These data show that losartan may possess advantages over doxazosin in improving vascular function in senescent SHR. This report emphasizes the importance of angiotensin II in vascular function alterations induced by aging in SHR.     

Microvascular cell death in spontaneously hypertensive rats during experimental inflammation

OBJECTIVE: Chronic hypertension is associated with an increased risk for tissue injury that may be mediated in part by endothelium and inflammatory cells. To clarify a possible underlying mechanisms, we examined leukocyte migration in the microcirculation and concomitant parenchymal cell death. METHODS: The mesentery of spontaneously hypertensive rats (SHRs) and their normotensive controls, Wistar Kyoto (WKY) rats, was examined with digital fluorescence microscopy after topical stimulation with an inflammatory mediator (f-met-leu-phe, 10(-8)M). The migratory pathways of individual leukocytes were traced, and at the same time cell death was detected by use of a life-death indicator (propidium iodide) over a period of 3 hours. RESULTS: Both WKY and SHR had a progressively increasing number of leukocytes migrating across the endothelium in postcapillary venules into the tissue parenchyma. But parenchymal cell death was detected in a random pattern in the mesentery tissue, without correlation to the migratory positions of the leukocytes. Although mature SHR rats (about 17 weeks) exhibited the same level of cell death as age-matched WKY rats, older WKY rats (about 30 weeks) had significantly lower levels of cell death, whereas the SHR rats maintained the same number of parenchymal cell death as mature animals. CONCLUSIONS: These results suggest that in the presence of an inflammatory mediator, the SHR may exhibit a stronger response to an inflammatory mediator than normotensive WKY rats in a fashion that is age, but not blood pressure, dependent. Parenchymal cell death does not correlate with migration of activated leukocytes at the microvascular level.     

Hypotensive and prophylactic effects of angiotensin II subtype 1 receptor antagonist, irbesartan, in stroke-prone spontaneously hypertensive rats

We determined the acute hypotensive effect of a single administration and the prophylactic effect of chronic treatment with Irbesartan, an angiotensin II receptor antagonist, on the development of end-organ damage in stroke-prone spontaneously hypertensive rats (SHRSP). The acute hypotensive effect was determined by a telemetrical method in SHRSP fed a normal diet. The prophylactic effect was examined by biochemical, histopathological and immunohistochemical methods in SHRSP fed a high-salt and low-protein diet. Irbesartan (3, 10, 30 and 100 mg/kg) reduced blood pressure in a dose-dependent manner without affecting heart rate. Irbesartan (3, 10 and 30 mg/kg) increased the survival rate in SHRSP fed a high-salt and low-protein diet. Furthermore, Irbesartan ameliorated the appearance of stroke symptoms in dose-dependent manner showing association with the prevention of microscopic lesions. Irbesartan ameliorated the increases in urinary protein excretion and N-acetyl-D-glucosamidase activity by preventing nephrosclerosis, as judged by microscopic observations, and ameliorated the increases in the expression of collagen IV and fibronectin in the kidney. These findings demonstrate that Irbesartan is a potent antihypertensive drug offering a protective effect on the development of hypertension-induced end-organ damages in SHRSP. Thus, Irbesartan is useful for the therapy of hypertension with end-organ damage.