内皮素受体阻断剂对糖尿病大鼠肾脏血管紧张素Ⅱ1型受体表达的影响

目的：观察糖尿病大鼠肾脏血管紧张素Ⅱ1型（AT1）受体的改变以及内皮素受体阻断剂bosentan对其影响。方法：将SD大鼠建成链脲佐菌素诱导的糖尿病模型,设非治疗组、bosentan治疗组和正常对照组。4周后采用免疫组织化学、Western blot及RT－PCR方法检测肾脏AT1受体基因和蛋白表达。结果：与SD对照组相比,糖尿病大鼠存在明显的蛋白尿和内生肌酐清除率升高,其肾脏AngⅡ水平明显升高,同时伴有AT1受体的mRNA和蛋白表达显著下降。bosentan能显著缓解上述异常。结论：糖尿病大鼠肾脏AngⅡ及AT1受体表达明显异常,bosentan具有治疗作用。     

烧伤后肾组织内皮素—1及其受体基因的表达

OBJECTIVE AND METHODS: We studied expression of messenger RNAS for endothelin-1 (ET-1) and its receptor subunits (ETA, ETB) by northern blot hybridization and in situ hybridization in rat kidney following 30% TBSA full thickness burns. RESULTS: Expressions of that ET-1, ETA, and ETB mRNA expression are all evidently increased at 1 hour postburn. ET-1 and ETA reached its maximal mRNA expression at 3 hour postburn. ET-1 mRNA distributed primarily on glomerular endothelial cells and tubular epithelial cells in cortex. ETA mRNA predominantly presented on smooth muscle cells of small arterioles in renal cortex. However, the peak time of ETB mRNA expression is at 6 hour postburn and mainly localized on renal medullary tubular epithelial and collecting duct cells. CONCLUSION: These findings suggest that 1. ET-1 acts principally as a local paracrine/autocrine peptide. 2. Increased ET-1 that activated ETA receptors accentuated expression on vascular smooth muscle cells will result in renal cortex ischemia. 3. Accentuated expression of ETB receptor on tubular epithelial cells may induce renal natriuretic action and reduction of water execretion. 4. Increased ET-1 and its receptors in kidney play an important role in the pathogenesis and development of renal function impairment following severe burn.     

缺血再灌流肾组织内皮素—1动态变化的实验研究

在大鼠肾缺血６０分钟再灌注的模型上观察不同时相肾静脉血、肾皮质、外髓和内髓的内皮素１（ＥＴ１）浓度变化，肾组织ＥＴ１光镜和电镜免疫组织化学变化。结果发现：缺血再灌流肾组织ＥＴ１基因表达及分泌明显增强，主要分布在血管内皮细胞及平滑肌细胞、系膜细胞、肾小管上皮细胞。其分布特点与细胞类型和活性有关。本实验结果提示了缺血再灌注肾内ＥＴ１的变化规律。     

Angiotensin II increases parathyroid hormone-related protein (PTHrP) and the type 1 PTH/PTHrP receptor in the kidney

Angiotensin II (AngII) participates in the pathogenesis of kidney damage. Parathyroid hormone (PTH)-related protein (PTHrP), a vasodilator and mitogenic agent, is upregulated during renal injury. The aim of this study was to investigate the potential relation between AngII and PTHrP system in the kidney. Different methods were used to find that both rat mesangial and mouse tubuloepithelial cells express PTHrP and the type 1 PTH/PTHrP receptor (PTH1R). In these cells, AngII increased PTHrP mRNA and protein production. In contrast, PTH1R mRNA was increased in mesangial cells and downregulated in tubular cells, but its protein levels were unmodified in both cells. AT(1) antagonist, but not AT(2), abolished AngII effects on PTHrP/PTH1R. The in vivo effect of AngII was further investigated by systemic infusion (a low dose of 50 ng/kg per min) into normal rats. In controls, PTHrP immunostaining was mainly detected in renal tubules. In AngII-infused rats, PTHrP staining increased in renal tubules and appeared in the glomerulus and the renal vessels. After AngII infusion, PTHR1 staining was markedly increased in all these renal structures at day 3 but remained elevated only in tubules at day 7. The AT(1) antagonist, but not the AT(2), significantly diminished AngII-induced PTHrP and PTHR1 overexpression in the renal tissue, associated with a decrease in tubular damage and fibrosis. The results indicate that AngII regulates renal PTHrP/PTH1R system via AT(1) receptors. These findings demonstrate that PTHrP upregulation occurs in association with the mechanisms of AngII-induced kidney injury.     

AT1 and AT2 receptor in the kidney: role in health and disease

The renin angiotensin system plays an important role in the control of body fluid and electrolyte homeostasis and blood pressure regulation. Angiotensin II is the most effector hormone of this system and functions mainly through stimulation of its subtype receptors, namely, the AT1 and AT2 receptors. Most of the known physiological and pathologic effects of angiotensin II are mediated through stimulation of the AT1 receptor. The knowledge about the involvement of the AT2 receptor in physiological and pathologic processes is still evolving. In the kidney, both the AT1 and AT2 receptors contribute to the regulation of renal hemodynamic and tubular functions. Also, these receptors regulate renal cellular growth and matrix formation. However, AT2 receptor possesses functions that counteract the effects of the AT1 receptor. The balance between the AT1 and AT2 receptors can determine the renal status in health and disease.     

缺血再灌流肾组织内皮素—1及其受体基因表达的实验研究

为了探究内皮素１（ＥＴ１）对肾功能的影响和作用方式，采用斑点杂交和原位杂交方法对大鼠缺血６０分钟再灌注肾组织ＥＴ１及其受体亚型（ＥＴＡ、ＥＴＢ）的基因表达进行了研究。结果发现：再灌流１小时，ＥＴ１、ＥＴＡ、ＥＴＢｍＲＮＡ均明显升高；再灌流２４小时仍维持较高水平。ＥＴ１和ＥＴＡｍＲＮＡ杂交信号再灌流３小时达高峰。ＥＴ１ｍＲＮＡ主要分布肾皮质小血管内皮细胞、髓质肾小管和集合管，ＥＴＡ受体ｍＲＮＡ则分布于上述小血管的平滑肌细胞。ＥＴＢ受体ｍＲＮＡ于再灌流６小时达高峰，主要分布髓质肾小管、集合管。说明缺血再灌流肾内皮素受体亚型上调在皮质以ＥＴＡ为主，在髓质以ＥＴＢ为主，分别与增强表达的ＥＴ１结合导致肾皮质缺血和水钠代谢异常。     

先兆子痫大鼠循环、胎盘及肾脏局部血管紧张素Ⅱ及其1型受体的表达

目的 研究先兆子痫大鼠模型循环系统、胎盘及肾脏局部血管紧张素Ⅱ（AngⅡ）及其1型受体（AT1）的表达。 方法 采用一氧化氮合酶抑制剂亚硝基左旋精氨酸甲酯（L-NAME）制备大鼠先兆子痫模型，分别比较先兆子痫大鼠、正常妊娠大鼠、未孕对照组大鼠动脉收缩压（SBP）、尿蛋白量(24 h)、肝肾功能，并对各组大鼠肾组织进行光镜检查。ELISA法和放射性免疫法分别测定各组大鼠血浆及肾脏局部匀浆液AngⅡ水平。Western印迹法检测大鼠胎盘局部AT1表达。免疫组化法及Western印迹法测定大鼠肾脏局部AT1的表达。 结果 在先兆子痫大鼠中，SBP及尿蛋白量(24 h)均较未孕对照组显著升高（P < 0.05）。先兆子痫大鼠血浆AngⅡ显著高于正常妊娠组[（0.706±0.086） ng/L比(0.540±0.085) ng/L，P < 0.05]；胎盘局部AT1表达比正常妊娠组升高46％（P < 0.05）；肾脏局部AngⅡ明显低于正常妊娠组[(65.543±40.634) ng/g比(165.543±33.078) ng/g，P < 0.05]；肾脏AT1表达减少，仅为正常妊娠组及未孕对照组的33％及59％（P < 0.05）。 结论 先兆子痫中，胎盘局部RAS表达增强，循环AngⅡ表达增高，肾脏局部RAS表达下调。     

Developmental changes in multispecific organic anion transporter 1 expression in the rat kidney

BACKGROUND: The cDNA of the multispecific organic anion transporter 1 (OAT1) responsible for the tubular secretion of organic anions was recently isolated. In the current study, we investigated the developmental changes in OAT1 expression in the rat kidney. METHODS: Ontogenic expression of rat OAT1 was investigated by Northern blot, in situ hybridization, Western blot, and immunohistochemical analysis. In addition, para-aminohippurate (PAH) accumulation was measured using fetal, neonatal, and adult rat kidney slices. RESULTS: In Northern blot analysis, OAT1 was detected as early as on embryonic day 18 in the fetal kidney. The expression level of OAT1 mRNA increased remarkably just after birth (postnatal day 0). In situ hybridization revealed OAT1 expression on embryonic day 19. In both the fetal and neonatal kidneys, OAT1 mRNA was localized in a relatively deep region in the cortex. Western blot analysis detected OAT1 protein on embryonic day 20, and the expression level increased after birth. Immunohistochemical analysis did not reveal OAT1 staining in the fetal kidneys. A faint signal of OAT1 protein was detected on postnatal day 0; thereafter, the expression level increased. In the functional study using kidney slices, low but definite probenecid-sensitive PAH accumulation was noted in fetal rat kidney on embryonic day 20. After birth, probenecid-sensitive PAH uptake was increased. CONCLUSIONS: The present study consistently demonstrates the remarkable increase of OAT1 expression after birth, and the immature excretory capacity of the proximal tubules of the neonatal kidney can be attributed, at least in part, to the low expression level of OAT1.     

Localization of fibroblast growth factor-2 (basic FGF) and FGF receptor-1 in adult human kidney.

BACKGROUND: The expression pattern of fibroblast growth factor-2 (FGF-2; basic FGF), a pleiotrophic growth factor, as well as one of its receptors (FGFR1), in the kidney is highly controversial. METHODS: Using an approach that combines multiple antibodies for immunohistochemistry and correlative in situ hybridization, we assessed the intrarenal expression of both FGF-2 and FGFR1 in 13 specimens of adult kidney removed during tumor nephrectomy. RESULTS: The FGF-2 expression pattern in the kidneys as detected by immunohistochemistry was variable and depended on the antibody used. The most consistent expression of FGF-2 protein was demonstrated in glomerular parietal epithelial cells, tubular cells (mainly of the distal nephron), as well as arterial endothelial cells. These locations also corresponded to areas of FGF-2 mRNA expression. Additionally, by immunohistochemistry, FGF-2 protein was detected in arterial smooth muscle cells and occasional podocytes. The expression of FGFR1 protein and mRNA was most consistently present in tubular cells of the distal nephron and in vascular smooth muscle cells. In situ hybridization, but not immunohistochemistry, also suggested FGFR1 expression in cells that could not be precisely identified within the glomerular tuft as well as some interstitial cells. CONCLUSION: These data suggest potential autocrine and paracrine pathways within the FGF-2 system, particularly within the vascular walls and in the distal nephron, and thereby provide information for further mechanistic understanding of the role of the FGF-2 system in human renal disease.     

Increased osteopontin expression following renal ablation is attenuated by angiotensin type 1 receptor antagonism.

Osteopontin is an extracellular matrix protein that is upregulated in renal injury. The aim of this study was to explore the renal expression of osteopontin in a model of progressive renal injury following subtotal nephrectomy (STNx) in rats and the effects of angiotensin type1 (AT1) receptor antagonist irbesartan on osteopontin expression. STNx or a sham operation was performed in 8-week-old Sprague-Dawley rats. STNx rats were given either irbesartan (15 mg/g) or no treatment for 12 weeks. Upregulation of osteopontin mRNA expression was observed in injured renal tubules as assessed by in situ hybridization (42 +/- 8 dpm/mm(2) v.s. control 7.7 +/- 0.6 dpm/mm(2), p < 0.01). Increased osteopontin expression was closely related to infiltration of monocytes/macrophages and increased cellular proliferation. Double immunohistochemical staining demonstrated co-existence of proliferating cell nuclear antigen and osteopontin positive staining in individual cells in kidney sections from STNx rats. The increase in osteopontin expression was inhibited by the AT1 receptor antagonist irbesartan (6.9 +/- 1.2 dpm/mm(2)), associated with attenuation of impaired renal function and pathology as well as decreased monocyte/macrophage infiltration and cellular proliferation. These findings suggest that osteopontin is upregulated in STNx rats and is reduced by AT1 receptor antagonism.     

Proapoptotic Fas ligand is expressed by normal kidney tubular epithelium and injured glomeruli

Fas ligand (FasL) is a cell membrane cytokine that can promote apoptosis through activation of Fas receptors. Fas receptor activation induces glomerular cell apoptosis in vivo and participates in tubular cell death during acute renal failure. However, there is little information on the expression of FasL in the kidney. This study reports that FasL mRNA and protein are present in normal mouse and rat kidney. In situ hybridization and immunohistochemistry showed that proximal tubular epithelium is the main site of FasL expression in the normal kidney. In addition, increased total kidney FasL mRNA and de novo FasL protein expression by glomerular cells were observed in two different models of glomerular injury : rat immune-complex proliferative glumerulonephritis and murine lupus nephritis. Both full-length and soluble FasL were increased in the kidneys of the mice with nephritis. Cultured murine proximal tubular epithelial MCT cells and primary cultures of murine tubular epithelial cells expressed FasL mRNA and protein. Tubular epithelium-derived FasL induced apoptosis in Fassensitive lymphoid cell lines but not in Fas-resistant lymphoid cell lines. By contrast, MCT cells grown in the presence of the survival factors of serum were resistant to FasL, and only became partially sensitive to apoptosis induced by high concentrations (100 ng/ml) of FasL upon serum deprivation. However, MCT cells stimulated with inflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide) increased cell surface Fas expression and were sensitized to apoptosis induced by FasL (FasL 55 +/- 5% versus control 8.3 +/- 4.1% apoptotic cells at 24 h, P < 0.05). Cytokine-primed primary cultures of tubular epithelial cells also acquired sensitivity to FasL-induced apoptosis. These results suggest that FasL expression by intrinsic renal cells may play a role in cell homeostasis in the normal kidney and during renal injury.