Leukocyte Adhesion Under Hemodynamic Flow Conditions.

Vascular endothelial cells (ECs) line the luminal side of all blood vessels and act as a selective barrier between blood and tissue. ECs are constantly exposed to biochemical and biomechanical stimuli from the blood and underlying tissue. Fluid shear stress acts in parallel to the vessel wall, resulting from friction of blood against EC. Despite the importance of flow on normal EC function, much of the information regarding EC function and dysfunction has been derived from cells harvested, grown, and studied in static culture.In order to study the effects of shear stress on EC function a number of in vitro models have been developed. This manuscript provides methodology for use of a system which enables recirculation of leukocytes and cell culture medium over the endothelium for a period of several minutes to days and enables investigation of the effects of prolonged leukocyte coculture on both the endothelial and leukocyte populations.

Introduction of inverse dose optimization for ultrasound-based high-dose-rate boost brachytherapy: how we do it in Kiel.

OBJECTIVES: To describe the introduction of inverse planning optimization for a two clinical target volume (CTV) concept in the online planning technique of temporary high-dose-rate brachytherapy for prostate cancer. METHODS AND MATERIALS: Dose-volume constraints were defined delivering a prescription dose of 8.5Gy for CTV1 (whole prostate) and 15Gy for CTV2 (peripheral zone). A total of 38 implants of 20 patients were inversely planned using the constraints and dose indices (D90 CTV1,2; V200 CTV1,2; D2 cc rectum; D0.1 cc urethra; dose nonhomogeneity ratio; and conformal index) compared against those derived from conventional planning (CP). RESULTS: The inversely planned (IP) treatment plans showed similar target volume coverage than by CP. The value of D90 CTV1 for CP was 5.62Gy and 5.63Gy for IPs. For CTV2, the D90 was also similar between both methods: 11.03Gy and 10.89Gy, respectively. Only V200 CTV2 was found to be significantly lower for CP than for IP: 5.76% vs. 8.14% (p<0.01). Values for D0.1 cc urethra were found to be: 9.57Gy and 9.02Gy, respectively. Rectal dosimetry: D2 cc Rectum was quite stable with 6.04Gy and 6.12Gy for CP and IP, respectively. The conformal index and dose nonhomogeneity ratio values for CTV1 and CTV2 for both planning types were very similar. CONCLUSIONS: After defining an objective second target volume CTV2 and introducing adequate IP constraints to the treatment planning system, clinically applicable treatment plans could be created by an IP approach. They feature user independency, time saving, and good preservation of the OARs.

Agonistic anti-ICAM-1 antibodies in scleroderma: activation of endothelial pro-inflammatory cascades.

BACKGROUND: Scleroderma (SSc) is a complex autoimmune disorder that can be characterised by the presence 2of circulating autoantibodies to nuclear, cytoplasmic and cell surface antigens. In particular antibodies directed against endothelial cell antigens (anti-endothelial cell antibodies; AECA) have been detected. ICAM-1 is an adhesion molecule expressed on the surface of human endothelial cells. We have previously shown that cross-linking ICAM-1 with monoclonal antibodies leads to pro-inflammatory activation of human endothelial and vascular smooth muscle cells and that cardiac transplant recipients with transplant associated vasculopathy make antibodies directed against ICAM-1. OBJECTIVES: To determine whether SSc patients make antibodies directed against ICAM-1 and whether these antibodies induce pro-inflammatory activation of human endothelial cells in vitro. METHODS: Using recombinant ICAM-1 as capture antigen, an ELISA was developed to measure ICAM-1 antibodies in sera from SSc patients. Antibodies were purified using ICAM-1 micro-affinity columns. HUVEC were incubated with purified anti-ICAM-1 antibodies and generation of reactive oxygen species, and expression of VCAM-1 was measured. RESULTS: Significantly elevated levels of anti-ICAM-1 antibodies were detected in patients with diffuse (dSSc; 10/31 32%) or limited (lSSc; 14/36 39%) scleroderma. Cross-linking of HUVEC with purified anti-ICAM-1 antibodies caused a significant increase in ROS production (2.471±0.408 fold increase above untreated after 150 min p<0.001), and significant increase in VCAM-1 expression (10.6±1.77% vs 4.12±1.33%, p<0.01). CONCLUSION: AECA from SSc patients target specific endothelial antigens including ICAM-1, and cause pro-inflammatory activation of human endothelial cells, suggesting that they are not only a marker of disease but that they contribute to its progression.

Head and neck (192)Ir HDR-brachytherapy dosimetry using a grid-based Boltzmann solver.

PURPOSE: To compare dosimetry for head and neck cancer patients, calculated with TG-43 formalism and a commercially available grid-based Boltzmann solver. MATERIAL AND METHODS: This study included 3D-dosimetry of 49 consecutive brachytherapy head and neck cancer patients, computed by a grid-based Boltzmann solver that takes into account tissue inhomogeneities as well as TG-43 formalism. 3D-treatment planning was carried out by using computed tomography. RESULTS: Dosimetric indices D90 and V100 for target volume were about 3% lower (median value) for the grid-based Boltzmann solver relative to TG-43-based computation (p < 0.01). The V150 dose parameter showed 1.6% increase from grid-based Boltzmann solver to TG-43 (p < 0.01). CONCLUSIONS: Dose differences between results of a grid-based Boltzmann solver and TG-43 formalism for high-dose-rate head and neck brachytherapy patients to the target volume were found. Distinctions in D90 of CTV were low (2.63 Gy for grid-based Boltzmann solver vs. 2.71 Gy TG-43 in mean). In our clinical practice, prescription doses remain unchanged for high-dose-rate head and neck brachytherapy for the time being.

[Heart and kidney--only together they are strong. On the cardiorenal and renocardiac syndrome. Case 5/2011]. / Herz und Nieren--nur gemeinsam sind sie stark. Über das kardiorenale und renokardiale Syndrom. Fall 5/2011.

HISTORY AND ADMISSION FINDINGS: We report on two patients with cardiorenal and renocardiac syndrome, respectively, who were treated with peritoneal dialysis. INVESTIGATIONS: Patient 1 suffered from dilated cardiomyopathy with an ejection fraction of 20%. There was no hint for an intrinsic renal disease, urinalysis showed microalbuminuria at the most. Due to progressive cardiac forward failure kidney dysfunction and diuretic-refractory volume retention developed. Patient 2 was admitted with an uremic syndrome and newly developed atrial fibrillation. Echocardiography revealed a hitherto unknown dilated cardiomyopathy. DIAGNOSIS, TREATMENT AND COURSE: Both patients were treated with continuous ambulatory peritoneal dialysis. This led to regression of the uremic complications. Sinus rhythm was restored in patient 2 after two weeks and cardiomyopathy was reversed after another 9 months. CONCLUSIONS: End-stage heart failure results in kidney dysfunction which can progress to a dialysis-dependent state. End-stage renal failure is often accompanied by cardiac dysfunction and failure.

[79-year-old patient with pulmorenal syndrome]. / Pulmorenales Syndrom bei einer 79-jährigen Patientin.

HISTORY AND ADMISSION FINDINGS: A 79-year-old female patient was referred with acute renal failure requiring haemodialysis and haemoptysis. INVESTIGATIONS: Kidney biopsy showed extracapillary proliferative glomerulonephritis with crescents in 7 from 15 glomeruli and sclerosis in the remaining. A computed tomography scan of the chest showed evidence of alveolar haemorrhage. Serologic testing revealed autoantibodies against the glomerular basement membrane (anti-GBM antibodies) and myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA). DIAGNOSIS, TREATMENT AND COURSE: The patient was diagnosed with goodpasture's disease and underwent immunosuppressive therapy including prednisolone, cyclophosphamide pulses and plasmapheresis, resulting in clearance of anti-GBM antibodies and discontinuation of haemoptysis. Renal function, however, did not recover and the patient remained on dialysis. CONCLUSIONS: Aggressive treatment including cyclophosphamide and plasma separation often ensures patient survival in goodpasture's disease, in most cases, however, renal function does not recover.

Microparticle formation after exposure of blood to activated endothelium under flow.

Increased numbers of circulating microparticles (MPs) are indicative of poor clinical outcome in a number of inflammatory disorders, including atherosclerosis. Platelets and megakaryocytes are a major source of MP and are identified by presence of CD42b on the MP surface. MP shed from activated platelets can be identified by presence of P-selectin (CD62P). Tissue factor (TF) is the principal initiator of blood coagulation and its activity has been identified in MPs derived from patient plasma, which may contribute to thrombosis. Here, we have investigated by flow cytometry the expression of TF and CD62P on MP after exposure of diluted whole blood to TNF-activated endothelial cells (EC) both under static conditions and in our newly established model of flow. MPs were significantly increased in blood subjected to flow and this was further enhanced after exposure of blood to TNF-activated EC. MP surface expression of CD62P or TF was upregulated following exposure to TNF-activated EC under flow compared with flow with nonactivated EC or after static coculture with and without prior EC activation. These data strongly suggest that interactions of blood with inflamed EC can modulate production of CD62P and TF bearing MP under flow conditions, and thus may contribute to a prothrombotic environment.

Leucocyte adhesion under haemodynamic flow conditions.

Vascular endothelial cells (EC) line the luminal side of all blood vessels and act as a selective barrier between blood and tissue. EC are constantly exposed to biochemical and biomechanical stimuli from the blood and underlying tissue. Fluid shear stress acts in parallel to the vessel wall, resulting from friction of blood against EC. Despite the importance of flow on normal EC function, much of the information regarding EC function and dysfunction has been derived from cells harvested, grown and studied in static culture. In order to study the effects of shear stress on EC function, a number of in vitro models have been developed. This chapter provides methodology for use of a system which enables recirculation of leucocytes and cell culture medium over the endothelium for a period of several minutes to days and enables investigation of the effects of prolonged leucocyte co-culture on both the endothelial and leucocyte populations.

[Interpretation of elevated serum troponin levels in end stage renal disease - case 2/2010]. / Bedeutung erhöhter Troponin-Werte bei terminaler Niereninsuffizienz - Fall 2/2010.

HISTORY AND ADMISSION FINDINGS: We report on a female patient with rheumatoid arthritis and end-stage renal-disease following AA-amyloidosis who presented with chest pain to the emergency department. INVESTIGATIONS: ECG showed no signs of ischemia, echocardiography revealed a concentric left ventricular hypertrophy with increased texture. Serum concentration of troponin I was mildly elevated whereas creatine kinase (CK)/ CK-MB were normal. DIAGNOSIS, TREATMENT AND COURSE: The chief complaints resolved spontaneously and there was no change in the serum troponin-I and CK/CK-MB concentrations. Coronary heart disease was ruled out by angiography and cardiac involvement of the underlying AA-amyloidosis was diagnosed. After one month, the patient suffered from a syncope complicated by a pelvic ring fracture with hemorrhagic shock and declined chronic dialysis treatment. CONCLUSION: Patients with end-stage renal disease may exhibit a persisting elevation of serum troponin concentration reflecting the high burden of cardiovascular disease. Myocardial infarction can be distinguished by the lack of increase in serial tests.

Expression of blood coagulation factors on monocytes after exposure to TNF-treated endothelium in a novel whole blood model of arterial flow.

Activated blood monocytes are a major source of tissue factor (TF), the principal initiator of blood coagulation. TF can be shed from the monocyte surface in association with microparticles (MPs) and increased numbers of circulating MPs are indicative of poor clinical outcome in a number of inflammatory disorders, including atherosclerosis. The mechanisms coupling inflammation with aberrant TF production/activity remain obscure but the protease-activated receptor (PAR) family has been implicated. We have previously shown (i) that freshly isolated human monocytes express low levels of cell surface PAR-2, (ii) that cell surface PAR-2 is rapidly upregulated from intracellular stores following mechanical stimulation, and (iii) that PAR-2 stimulation results in elevation of intracellular calcium and cytokine release. Here, we have investigated the expression of PAR-2 on monocytes exposed to TNF-activated endothelial cells both under static conditions and in our newly-established model of arterial flow, using diluted whole blood. Monocyte surface PAR-2 expression was upregulated following static exposure to activated EC and with laminar (atheroprotective) arterial flow there was a further increase in monocyte PAR-2 expression. We have also shown under arterial flow conditions that exposure to TNF-stimulated EC resulted in a significant increase in expression of TF on monocytes compared to that on cells exposed to quiescent EC. These data strongly suggest that direct or indirect interactions with inflamed EC can modulate expression of PAR-2 and TF on the monocyte cell surface.

ICAM-1 signaling in endothelial cells.

Intercellular adhesion molecule-1 (ICAM-1; CD54) is a 90 kDa member of the immunoglobulin (Ig) superfamily and is critical for the firm arrest and transmigration of leukocytes out of blood vessels and into tissues. ICAM-1 is constitutively present on endothelial cells, but its expression is increased by proinflammatory cytokines. The endothelial expression of ICAM-1 is increased in atherosclerotic and transplant-associated atherosclerotic tissue and in animal models of atherosclerosis. Additionally, ICAM-1 has been implicated in the progression of autoimmune diseases. We and others have shown that the ligation of ICAM-1 on the surface of endothelial or smooth muscle cells with monoclonal antibodies, via its main leukocyte ligand, lymphocyte function associated molecule (LFA)-1, or with antibodies derived from patient serum, leads to the activation of several proinflammatory signaling cascades, and to the rearrangement of the actin cytoskeleton. A circulating or soluble form of ICAM-1 (sICAM-1) has been measured in various body fluids, with elevated levels being observed in patients with atherosclerosis, heart failure, coronary artery disease and transplant vasculopathy. sICAM-1 has signaling properties in several cell types, including EC, and invokes a range of proinflammatory responses. Thus, we propose that in addition to acting as a leukocyte adhesion molecule, ICAM-1 directly contributes to inflammatory responses within the blood vessel wall by increasing endothelial cell activation and augmenting atherosclerotic plaque formation.

The epithelial membrane protein 1 is a novel tight junction protein of the blood-brain barrier.

In the central nervous system, a constant microenvironment required for neuronal cell activity is maintained by the blood-brain barrier (BBB). The BBB is formed by the brain microvascular endothelial cells (BMEC), which are sealed by tight junctions (TJ). To identify genes that are differentially expressed in BMEC compared with peripheral endothelial cells, we constructed a subtractive cDNA library from porcine BMEC (pBMEC) and aortic endothelial cells (AOEC). Screening the library for differentially expressed genes yielded 26 BMEC-specific transcripts, such as solute carrier family 35 member F2 (SLC35F2), ADP-ribosylation factor-like 5B (ARL5B), TSC22 domain family member 1 (TSC22D1), integral membrane protein 2A (ITM2A), and epithelial membrane protein 1 (EMP1). In this study, we show that EMP1 transcript is enriched in pBMEC compared with brain tissue and that EMP1 protein colocalizes with the TJ protein occludin in mouse BMEC by coimmunoprecipitation and in rat brain vessels by immunohistochemistry. Epithelial membrane protein 1 expression was transiently induced in laser-capture microdissected rat brain vessels after a 20-min global cerebral ischemia, in parallel with the loss of occludin immunoreactivity. The study identifies EMP1 as a novel TJ-associated protein of the BBB and suggests its potential role in the regulation of the BBB function in cerebral ischemia.

Expression of endothelial intercellular adhesion molecule-1 is determined by genotype: effects on efficiency of leukocyte adhesion to human endothelial cells.

Two biallelic polymorphisms, previously described in the human intercellular adhesion molecule (ICAM)-1 gene at codon 241 (glycine [G] to arginine [R] substitution) and codon 469 (glutamic acid [E] to lysine [K] substitution) have been associated with a number of diseases including myocardial infarction, transplant rejection, and diabetes. However, the functional significance of these polymorphisms has not been determined. ICAM-1 cell surface expression and ICAM-1-mediated leukocyte adhesion were investigated using Cos7 transfected with ICAM-1 polymorphic variants or human umbilical vein endothelial cells (HUVEC) of different ICAM-1 genotypes. There was significantly higher expression of surface ICAM-1 on Cos7 transfected with a plasmid encoding the GE (G241/E469) ICAM-1 variant or untreated HUVEC of GEGE (G241/E469 homozygous genotype). ICAM-1-mediated adhesion of peripheral blood mononuclear cells (PBMC) to GE-Cos7 cells or TNF-treated GEGE HUVEC was significantly increased. However, there was no significant difference in adhesion of PBMC to recombinant ICAM-1 of each polymorphic variant plated onto plastic wells. We conclude that the GE genotype of ICAM-1 is associated with greater cell surface expression of ICAM-1, which in turn leads to greater adhesion of leukocytes. This may explain the previously described associations of ICAM-1 polymorphisms with chronic inflammatory disease.

Proteome analysis of human substantia nigra in Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is the most common neurodegenerative disorder involving the motor system. Although not being the only region involved in PD, affection of the substantia nigra and its projections is responsible for some of the most debilitating features of the disease. To further advance a comprehensive understanding of nigral pathology, we conducted a tissue based comparative proteome study of healthy and diseased human substantia nigra. RESULTS: The gross number of differentially regulated proteins in PD was 221. In total, we identified 37 proteins, of which 16 were differentially expressed. Identified differential proteins comprised elements of iron metabolism (H-ferritin) and glutathione-related redox metabolism (GST M3, GST P1, GST O1), including novel redox proteins (SH3BGRL). Additionally, many glial or related proteins were found to be differentially regulated in PD (GFAP, GMFB, galectin-1, sorcin), as well as proteins belonging to metabolic pathways sparsely described in PD, such as adenosyl homocysteinase (methylation), aldehyde dehydrogenase 1 and cellular retinol-binding protein 1 (aldehyde metabolism). Further differentially regulated proteins included annexin V, beta-tubulin cofactor A, coactosin-like protein and V-type ATPase subunit 1. Proteins that were similarly expressed in healthy or diseased substantia nigra comprised housekeeping proteins such as COX5A, Rho GDI alpha, actin gamma 1, creatin-kinase B, lactate dehydrogenase B, disulfide isomerase ER-60, Rab GDI beta, methyl glyoxalase 1 (AGE metabolism) and glutamine synthetase. Interestingly, also DJ-1 and UCH-L1 were expressed similarly. Furthermore, proteins believed to serve as internal standards were found to be expressed in a constant manner, such as 14-3-3 epsilon and hCRMP-2, thus lending further validity to our results. CONCLUSION: Using an approach encompassing high sensitivity and high resolution, we show that alterations of SN in PD include many more proteins than previously thought. The results point towards a heterogeneous aetiopathogenesis of the disease, including alterations of GSH-related proteins as well as alterations of proteins involved in retinoid metabolism, and they indicate that proteins involved in familial PD may not be differentially regulated in idiopathic Parkinson's disease.

Major differences in gene expression in human coronary smooth muscle cells after nebivolol or metoprolol treatment.

OBJECTIVE: Vascular smooth muscle cells play a pivotal role in all stages of atherogenesis. Targeting their inflammatory and proliferative qualities might therefore inhibit the progression of atherosclerosis. This study aimed to characterize and compare the effects of the beta-receptor antagonists nebivolol and metoprolol on gene expression in human coronary artery smooth muscle cells (hcaSMC). METHODS AND RESULTS: hcaSMC were incubated with nebivolol or metoprolol (10(-5) mol/l) for 72 h. The downregulated genes are involved in inflammatory processes, oxidative stress and smooth muscle cell proliferation: i.e. downregulated were by nebivolol: interleukin-1alpha, cyclooxygenase-2, tumor-necrosis-factor (TNF)-alpha-induced protein 6, PDGF-A, growth-related oncogenes 2 and 3. Metoprolol increased the expression of interleukin-1alpha, cyclooxygenase-1, TNF-alpha-induced protein 3, heme oxygenase 1 and granulocyte/macrophage-colony-stimulating factor. In addition downregulated was monocyte chemoattractant protein 1 (MCP-1) mRNA by nebivolol. Nebivolol (10(-5) mol/l) reduced the amount of basal NF-kappaB after 48 and 52 h but not metoprolol. In the culture supernatants, MCP-1 concentrations were reduced by nebivolol. CONCLUSIONS: Nebivolol induced changes in the expression of inflammatory mediators in hcaSMC. These results add to data that suggest specific anti-inflammatory qualities of a beta-blocker of the third generation in comparison to metoprolol.

Influence of nebivolol and metoprolol on inflammatory mediators in human coronary endothelial or smooth muscle cells. Effects on neointima formation after balloon denudation in carotid arteries of rats treated with nebivolol.

OBJECTIVE AND BACKGROUND: Inflammation plays a critical role in all stages of atherogenesis. Proliferating vascular smooth muscle cells (SMC) and endothelial cells (EC) enhancing the inflammatory response, both contribute to the progression of atherosclerosis. Anti-proliferative, anti-inflammatory and anti-oxidative therapy seems to be a promising therapeutic strategy. The aim of this study was to assess the anti-proliferative and anti-inflammatory effect of the beta-blocker nebivolol in comparison to metoprolol in vitro and to find out whether nebivolol inhibits neointima formation in vivo. METHODS AND RESULTS: Real-time-RT-PCR revealed a decrease in VCAM-1, ICAM-1, PDGF-B, E-selectin and P-selectin mRNA expression in human coronary artery EC and SMC incubated with nebivolol for 72 hours while metoprolol did not have this effect. Nebivolol reduced MCP-1 and PDGF-BB protein in the culture supernatant of SMC and EC, respectively. Sprague-Dawley rats were treated with nebivolol for 0 or 35 days before and 28 days after carotid balloon injury. Immunohistological analyses showed that pre-treatment with nebivolol was associated with a decreased number of SMC layers and macrophages and an increased lumen area at the site of the arterial injury. The intima area was reduced by 43% after pre-treatment. CONCLUSION: We found that nebivolol reduced the expression of proinflammatory genes in endothelial cells and vascular smooth muscle cells in vitro whereas metoprolol did not. In vivo, nebivolol inhibited neointima formation by reducing SMC proliferation and macrophage accumulation.

Secondary syphilis after liver transplantation: case report and review of the literature.

Syphilitic disease is uncommon, but its incidence has increased worldwide in the last few years. An unusual manifestation of secondary syphilis after orthotopic liver transplantation is described which confirms that lues should be considered in patients with immune deficiency and abnormal liver function tests.

Stimulation of serum- and glucocorticoid-regulated kinase-1 gene expression by endothelin-1.

The serum- and glucocorticoid-regulated kinase-1 (SGK1) participates in the regulation of sodium homeostasis and blood pressure by mineralocorticoids. Aldosterone rapidly induces SGK1 transcription, which contributes to the activation of renal epithelial sodium channels. Another important regulator of blood pressure is the vasoactive hormone endothelin-1 (ET-1) that is systemically upregulated in chronic renal failure. In the present study, we investigated whether ET-1 modulates SGK1 expression, and thereby might explain some of its hypertensive effects. As assessed by real-time PCR analysis, ET-1 triggered the rapid increase of SGK1 mRNA levels in A-10 smooth muscle cells and also in intact aortas of adult rats. In A-10 cells transcriptional activation was associated with a more than 6-fold upregulation of SGK1 protein expression and in similar range as found after treatment with aldosterone. A stimulatory effect of ET-1 was not only observed in isolated cells, but also in an animal model. Upon subtotal nephrectomy (SNX) of rats, myocardial ET-1 levels strongly increased, which was followed by a more than 2-fold induction of SGK1 expression in the left ventricle. The myocardial upregulation of SGK1 was completely abrogated by a specific ET(A) receptor antagonist, thereby substantiating the in vivo role of ET-1 in SGK1 expression. Thus, these data demonstrate that ET-1 increases expression of SGK1 in vivo and in vitro, and therefore indicate that SGK1 upregulation might be involved in ET-1-dependent regulation of blood pressure and cardiac modelling during mild renal failure.

Effects of combined endothelin and angiotensin II antagonism on growth factor-induced proliferation of vascular smooth muscle cells isolated from uremic rats.

BACKGROUND: The activation of both the renin-angiotensin-aldosterone and endothelin (ET) system in uremia contributes to the development of cardiovascular disease. The combination of ET receptor antagonists and inhibitors of the angiotensin-converting enzyme (ACE) or angiotensin II type 1 (AT,) receptor could therefore inhibit atherogenesis. We studied the effects of different medications on growth-factor-induced proliferation of vascular smooth muscle cells (VSMC) isolated from uremic rats. METHODS: Subtotally nephrectomized rats (SNX) were treated with an ETA receptor antagonist, losartan, trandolapril, or the combinations of an ETA receptor antagonist and losartan or trandolapril for 12 weeks. Proliferation induced by different growth factors in isolated aortal SMC was measured using a BrdU-ELISA. RESULTS: Maximum proliferation in response to PDGF-BB, bFGF, and TNF-alpha which was higher in untreated SNX than in controls (PDGF-BB: 486.60 +/- 8.27% versus 346.74 +/- 4.60%, n=8), was reduced after monotherapy with losartan or the ETA receptor antagonist. VSMC from trandolapril-treated rats showed an increased response to all growth factors (PDGF-BB: 663.48 +/- 7.00%, n=8). After combined therapy with the ETA receptor antagonist and trandolapril, maximum proliferation was lower than in untreated SNX (PDGF-BB: 162.6 +/- 1.40%; n=8; p < or = 0.01). Combined treatment with losartan and the ETA receptor antagonist attenuated the maximum levels of VSMC proliferation induced by PDGF-BB, bFGF, and TNF. CONCLUSIONS: In contrast to an increased response after trandolapril monotherapy, combined treatment of SNX with an ETA receptor antagonist and trandolapril reduced growth-factor-induced VSMC proliferation in vitro. Further investigations in uremic patients have to clarify whether the combination of endothelin receptor antagonists and ACE inhibitors inhibits atherogenesis.