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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Unilateral ureteral obstruction (UUO) in the neonate impairs growth of the ipsilateral kidney. Since renal renin expression is increased by UUO, we hypothesized that, by activation of AT1 receptors, angiotensin II (ANG II) regulates expression of transforming growth factor-beta 1 (TGF-beta 1) and epidermal growth factor (EGF) in the obstructed kidney. Sprague-Dawley rats underwent left UUO or sham operation within the first 48 h of life and received losartan, 40 mg.kg-1.day-1, or saline. After 14 days, steady-state renal mRNA was determined for renin, TGF-beta 1, EGF, and clusterin. Losartan reduced the DNA content of the intact kidneys but did not further decrease that of the obstructed kidney. Losartan increased renal renin expression and decreased EGF expression by 80%, regardless of UUO. In contrast, losartan reduced TGF-beta 1 expression by 34% in obstructed kidneys but did not affect TGF-beta 1 in intact kidneys. Losartan increased clusterin expression by 60% in obstructed kidneys and seven-fold in intact kidneys. We conclude that activation of the ANG II AT1 receptor is necessary for normal renal growth and that TGF-beta 1 is regulated by AT1 receptors in the obstructed, but not intact, kidneys. Through AT1 receptors, endogenous ANG II stimulates EGF and inhibits clusterin expression.
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PMID:Regulation of renal growth factors and clusterin by AT1 receptors during neonatal ureteral obstruction. 761 52

TCV-116 [(+/-)-(cyclohexyloxycarbony-loxy)ethyl2-ethoxy-1-[[2' -(1H- tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimidazole-7-carboxylate ], a nonpeptide selective angiotensin II type I receptor (AT1 receptor) antagonist, at the dose of 0.1, 1 or 10 mg kg-1 day-1, was orally given to 22-week-old stroke-prone spontaneously hypertensive rats (SHRSP) for 10 weeks (from the age of 22-32 weeks) to examine the effects on gene expression of transforming growth factor-beta 1 (TGF-beta 1) and extracellular matrix proteins in the heart and blood vessels. Tissue messenger RNA (mRNA) was measured by northern blot analysis, with a specific complementary DNA probe. In the heart, left ventricular mRNA levels for fibronectin; types I, III and IV collagen; and laminin were significantly higher in SHRSP than control Wistar-Kyoto rats. In the mesenteric artery and aorta of SHRSP, TGF-beta 1 mRNA and the mentioned extracellular matrix protein mRNAs were increased compared with Wistar-Kyoto rats. Thus, the expression of various genes was up-regulated in cardiovascular tissues of SHRSP. Treatment of SHRSP with TCV-116 suppressed the gene expression of the mentioned extracellular matrix proteins and TGF-beta 1 in both heart and blood vessels in a dose-dependent fashion. Furthermore, TCV-116 regressed cardiac hypertrophy and lessened the medial hypertrophy of the aorta in SHRSP. These results show that angiotensin AT1 receptor antagonist in vivo can inhibit the gene expression of TGF-beta 1 and extracellular matrix proteins in hypertensive cardiovascular tissues. These effects may contribute to the beneficial effects of AT1 receptor antagonist on hypertensive cardiac hypertrophy and vascular thickening.
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PMID:Angiotensin II type I receptor antagonist inhibits the gene expression of transforming growth factor-beta 1 and extracellular matrix in cardiac and vascular tissues of hypertensive rats. 771 6

A murine SV40-transformed renal epithelial cell line derived from medullary thick ascending limb of Henle's loop (MTAL) was established and characterized by morphology, antigen expression, and biochemical criteria. These MTAL cells express a single class of high-affinity receptors for angiotensin II (ANG II) and transcripts for the AT1 subtype of ANG II receptors. ANG II, in a dose-dependent manner, induced proliferation of MTAL cells. This observation is in striking contrast to syngeneic proximal tubular cells in which it was previously shown that the peptide induced cellular hypertrophy and slightly inhibited proliferation [G. Wolf and E. G. Neilson. Am. J. Physiol. 259 (Renal Fluid Electrolyte Physiol. 28: F768-F777, 1990]. The AT1-receptor antagonist losartan (10(-6) M), but not an AT2-receptor antagonist, blocked the mitogenic effects of ANG II in MTAL cells. Coincubation of quiescent MTAL cells with ANG II and 5% fetal calf serum further increased proliferation compared with cells grown only in serum. In contrast to proximal tubular cells, ANG II failed to induce transforming growth factor-beta 1 mRNA and protein synthesis in MTAL cells. Our data collectively suggest that ANG II is a mitogen for MTAL cells in vitro. Therefore, epithelial cells derived from different parts of the nephron, even when transformed with SV40 virus and while under cell culture conditions, exhibit a distinct pattern of growth behavior after stimulation with ANG II.
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PMID:ANG II is a mitogen for a murine cell line isolated from medullary thick ascending limb of Henle's loop. 777 22

The in vivo effects of alacepril (1-[(S)-3-acetylthio-2-methylpropanoyl]- L-prolyl-L-phenylalanine), an angiotensin converting enzyme inhibitor, and SC-52458 (5-[(3,5-dibutyl-1H-1,2,4-triazol-1- yl)methyl]-2-[2-(1H-tetrazol-5-ylphenyl)]pyridine), an angiotensin AT1 receptor antagonist, were examined on the cardiac and aortic gene expressions of extracellular matrices and TGF-beta 1 in young spontaneously hypertensive rats (SHR). In SHR, types I and III collagen mRNAs were increased in the left ventricle, and in contrast, fibronectin, collagen IV, and transforming growth factor-beta 1 (TGF-beta 1) mRNAs were increased in aorta, compared with those in Wistar-Kyoto rats. All the enhanced mRNAs in both organs in SHR were significantly inhibited by the short-term treatment with the above two drugs. Thus, angiotensin AT1 receptor may play an important role in the regulation of extracellular matrices and TGF-beta 1 expressions in SHR.
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PMID:Role of angiotensin II in extracellular matrix and transforming growth factor-beta 1 expression in hypertensive rats. 782 53

Recent evidence indicates that transforming growth factor-beta 1 (TGF-beta 1) plays an important role in renal fibrosis via stimulation of extracellular matrix synthesis. The present study was undertaken to investigate the role of angiotensin II type I receptor (AT1 receptor) in hypertension-induced renal injury. Twenty-two-week-old stroke-prone spontaneously hypertensive rats (SHRSP), which had established hypertension and moderate renal damage, were orally given TCV-116, a selective non-peptide AT1 receptor antagonist (0.1, 1 or 10 mg/kg/day), enalapril (10 mg/kg/day) or vehicle once a day for 10 weeks. At the end point of the treatment, we examined renal function, the gene expressions of TGF-beta 1 and extracellular matrix components in the interstitium [collagen types I (COI) and III (COIII), fibronectin (FN)] and the basement membrane (COIV and laminin), and renal microscopic morphology in rats aged 32 weeks. In vehicle-treated 32 week-old SHRSP with renal dysfunction and nephrosclerosis, renal mRNA levels for TGF-beta 1, COI, COIII, FN, COIV were all several-fold higher than in WKY. Thus, renal TGF-beta 1 gene expression was enhanced in SHRSP, which may contribute to the increased renal expressions of COI, COIII, FN, COIV in SHRSP. Treatment with TCV-116 (0.1 mg/kg/day) in SHRSP, in spite of no reduction of blood pressure, decreased renal mRNA levels for TGF-beta 1, COI, COIII, FN, COIV, being accompanied by the significant decrease in urinary protein and albumin excretion, blood urea nitrogen and plasma creatinine. Treatment with TCV-116 (10 mg/kg/day) in SHRSP decreased mRNAs for TGF-beta 1, COI, COIII, FN and COIV to almost the same levels as WKY, being associated with normalization of urinary protein and albumin excretion and the prevention of nephrosclerosis, as judged by microscopic histological observations. On the other hand, the effects of enalapril (10 mg/kg/day) on the above mentioned mRNA levels, renal function and renal morphology were weaker than those of TCV-116 (10 mg/kg/day) and were as much as TCV-116 (1 mg/kg/day). These results suggest that independently of hypotensive action, AT1 receptor antagonist has a potent renal protective effect by inhibiting the gene expression of renal TGF-beta 1 and extracellular matrix components.
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PMID:Contribution of renal angiotensin II type I receptor to gene expressions in hypertension-induced renal injury. 785 93

We examined the effects of TCV-116, a non-peptide selective AT1 receptor antagonist, on cellular phenotype and on the expression of the transforming growth factor-beta 1 (TGF-beta 1) and extracellular matrix genes in the kidneys of stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP were given vehicle or TCV-116 (10 mg/kg/day) by gastric gavage for 10 weeks (from the age of 22 to 32 weeks). Renal mRNA levels were measured by Northern blot analysis. In vehicle-treated 32-week-old SHRSP, urinary albumin excretion per 24 h was about 26-fold greater than that in age-matched Wistar-Kyoto (WKY) rats, and the mRNA levels of renal TGF-beta 1, fibronectin and collagen types I and III in SHRSP were all several-fold higher than those in WKY. Immunohistochemical studies showed the prominent presence of alpha-smooth muscle actin-expressing glomerular cells in SHRSP, in contrast to their absence in WKY. Treatment of SHRSP with TCV-116 decreased urinary albumin excretion and renal mRNA levels for TGF-beta 1 and for the above-mentioned extracellular matrix components. TCV-116 prevented the phenotypic modulation of glomerular cells in SHRSP. These results suggest that AT1 receptor antagonists may have powerful renal protective effects.
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PMID:Renal protective effect of TCV-116 in stroke-prone spontaneously hypertensive rats. 788 1

Increasing evidence suggests that angiotensin II (Ang II) may act as a growth factor for the heart. However, direct effects of Ang II on mammalian cardiac cells (myocytes and nonmyocytes), independent of secondary hemodynamic and neurohumoral effects, have not been well characterized. Therefore, we analyzed the molecular phenotype of cultured cardiac cells from neonatal rats in response to Ang II. In addition, we examined the effects of selective Ang II receptor subtype antagonists in mediating the biological effects of Ang II. In myocyte culture, Ang II caused an increase in protein synthesis without changing the rate of DNA synthesis. In contrast, Ang II induced increases in protein synthesis, DNA synthesis, and cell number in nonmyocyte cultures (mostly cardiac fibroblasts). The Ang II-induced hypertrophic response of myocytes and mitogenic response of fibroblasts were mediated primarily by the AT1 receptor. Ang II caused a rapid induction of many immediate-early genes (c-fos, c-jun, jun B, Egr-1, and c-myc) in myocyte and nonmyocyte cultures. Ang II induced "late" markers for cardiac hypertrophy, skeletal alpha-actin and atrial natriuretic factor expression, within 6 hours in myocytes. Ang II also caused upregulation of the angiotensinogen gene and transforming growth factor-beta 1 gene within 6 hours. Induction of immediate-early genes, late genes, and growth factor genes by Ang II was fully blocked by an AT1 receptor antagonist but not by an AT2 receptor antagonist. These results indicate that: (1) Ang II causes hypertrophy of cardiac myocytes and mitogenesis of cardiac fibroblasts, (2) the phenotypic changes of cardiac cells in response to Ang II in vitro closely mimic those of growth factor response in vitro and of load-induced hypertrophy in vivo, (3) all biological effects of Ang II examined here are mediated primarily by the AT1 receptor subtype, and (4) Ang II may initiate a positive-feedback regulation of cardiac hypertrophic response by inducing the angiotensinogen gene and transforming growth factor-beta 1 gene.
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PMID:Molecular characterization of angiotensin II--induced hypertrophy of cardiac myocytes and hyperplasia of cardiac fibroblasts. Critical role of the AT1 receptor subtype. 834 86

In addition to its vasoconstrictor and aldosterone-stimulating action, angiotensin II also drives cell growth and replication in the cardiovascular system, which may result in myocardial hypertrophy and hypertrophy or hyperplasia of conduit and resistance vessels in certain subjects. These actions are mediated through angiotensin II receptors (subtype AT1), which activate the G protein, phospholipase C, diacylglycerol and inositol trisphosphate pathway, to increase the expression of certain protooncogenes (c-fos, c-myc and c-jun) and growth factors (platelet-derived growth factor-A-chain, transforming growth factor-beta 1 and basic fibroblast growth factor). The cellular responses to angiotensin II in vascular smooth muscle have been shown in different hypertensive vessels to be either hypertrophy alone, hypertrophy and DNA synthesis without cell division (polyploidy) or DNA synthesis with cell division (hyperplasia). In genetic hypertension, the altered structure of small arteries is due to either cellular hyperplasia or remodeling, whereas in renovascular hypertension there is hypertrophy of vascular smooth muscle cells. Angiotensin II also increases synthesis of some matrix components, activates blood monocytes and is thrombogenic. Angiotensin-converting enzyme (ACE) inhibitors prevent or reverse vascular hypertrophy in animal models of hypertension; this seems to be a class effect, shared to some extent with calcium channel blocking agents. In human hypertension, ACE inhibitors reduce the increased media/lumen ratio of large and small arteries in hypertension and increase arterial compliance. These properties are also shared by losartan, the first of the new class of angiotensin II receptor (AT1) antagonists. The clinical implications of these findings need to be tested through rigorous and prospective clinical trials.
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PMID:The renin-angiotensin system and vascular hypertrophy. 883 52

Accumulating evidence indicate that various growth-related genes, growth factors and extracellular matrix components play a central role in the pathogenesis of cardiovascular and renal diseases by regulating cellular phenotype, growth and migration or promoting tissue fibrosis. Treatment of hypertensive rats with an angiotensin II type 1-receptor (AT1-receptor) antagonist normalizes cardiac phenotypic modulation and the increased fibrosis-related gene expressions in hypertrophied heart, leading to the improvement of cardiac dysfunction. The AT1-receptor antagonist can inhibit protooncogenes (c-fos, c-jun and Egr-1) and fibronectin gene expressions in rat balloon-injured artery, which is associated with the inhibition of neointima formation. Furthermore, the AT1-receptor antagonist prevents either the phenotypic modulation of glomerular mesangial cells or the increase in transforming growth factor-beta 1 expression in nephrosclerosis. Thus, the AT1-receptor antagonist in vivo potently inhibits the expression of growth-related gene and extracellular matrix and inhibits cellular phenotypic modulation. The AT1-receptor is responsible for the pathogenesis and development of cardiovascular and renal diseases.
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PMID:[Role of the renin-angiotensin system in cardiovascular and renal diseases]. 921 48

The interaction of ANG II with platelet-derived growth factor (PDGF)-BB-induced DNA synthesis was studied in cultured rat aortic smooth muscle cells. PDGF-BB-induced DNA synthesis was delayed (approximately 6-8 h) by ANG II as shown by a time-course experiment. Losartan, an AT1-receptor antagonist, blocked the transient inhibitory effect of ANG II, whereas the AT2-receptor antagonist PD-123319 had no effect. Autocrine- or paracrine-acting transforming growth factor-beta 1 (TGF-beta 1), believed to be a mediator of ANG II-induced inhibitory effects, was not responsible for the delay of PDGF-BB-induced DNA synthesis, because a potent TGF-beta 1 neutralizing antibody could not reverse this effect of ANG II, nor was the delay of the PDGF-BB effect caused by inhibition of PDGF-beta-receptor phosphorylation as shown by Western blot analysis of immunoprecipitated PDGF-beta receptor. In conclusion, our results show that ANG II can exert a transient inhibitory effect on PDGF-BB-induced proliferation via the AT1 receptor.
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PMID:PDGF-BB-induced DNA synthesis is delayed by angiotensin II in vascular smooth muscle cells. 961 86


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