Functional effects of urotensin-II on intracellular pH regulators in human radial artery smooth muscle cells.

The regulation of intracellular pH (pHi) plays a vital role in various cellular functions. We previously demonstrated that three different acid extruders, the Na+-H+ exchanger (NHE), Na+-HCO3- co-transporter (NBC) and H+-linked monocarboxylate transporter (MCT), functioned together in cultured human radial artery smooth muscle cells (HRASMCs). However, the functions of acid-loading transporters in HRASMCs remain poorly understood. Urotensin II (U-II), one of the most potent vasoconstrictors, is highly expressed in many cardiovascular diseases. The aim of this present study was to determine the concentration effect of U-II (3 pM∼100 nM) on the functional activity of pHi regulators in HRASMCs. Cultured HRASMCs were derived from segments of human radial arteries obtained from patients undergoing bypass grafting. Changes in pHi recovery due to intracellular acidification and alkalization induced by NH4Cl prepulse and Na-acetate prepulse, respectively, were detected by microspectrofluorimetry with the pH-sensitive fluorescent dye BCECF. Our present study showed that (a) U-II increased the activity of NHE in a concentration-dependent manner but did not change that of NBC or MCT or resting pHi, (b) the Cl--OH- exchanger (CHE) facilitated base extrusion, and (c) U-II induced a concentration-dependent increase in the activity of CHE. In conclusion, for the first time, our results highlight a concentration-dependent increase in the activity of NHE and CHE, but not NBC and MCT, induced by U-II in HRASMCs.

Histological structure affects recellularization of decellularized arteries.

Decellularized arteries were prepared to evaluate the in vivo recellularization of biological material after implantation. Porcine aortas and radial arteries were decellularized using high-hydrostatic pressure to form materials with histologically-different structures. Successful removal of cells from decellularized arteries was evaluated by hematoxylin-eosin staining and measurement of residual DNA. Cell remnants were eliminated completely from the decellularized arteries, and histological structures were preserved. Cells adhered to all decellularized artery samples, but infiltration of cells was observed only from the adventitial side of the decellularized radial artery. Rats were implanted subcutaneously with a decellularized aorta or radial artery to evaluate in vivo performance. Decellularized aortic tissue prevented cell infiltration better than that of the decellularized radial artery, suggesting that the elastin lamina in decellularized tissues prevents cell infiltration and suppresses recellularization.

Impact of fibroblast growth factor 21 on the secretome of human perivascular preadipocytes and adipocytes: a targeted proteomics approach.

CONTEXT: Perivascular adipose tissue (PVAT) is suggested to impact on vascular cells via humoral factors, possibly contributing to endothelial dysfunction and atherosclerosis. OBJECTIVE: To address whether the hepatokine fibroblast growth factor (FGF) 21 affects the PVAT secretome. METHODS: Human perivascular (pre)adipocytes were subjected to targeted proteomics and whole-genome gene expression analysis. RESULTS: Preadipocytes, as compared to adipocytes, secreted higher amounts of inflammatory cytokines and chemokines. Adipocytes released higher amounts of adipokines [e.g. adipisin, visfatin, dipeptidyl peptidase 4 (DPP4), leptin; p < 0.05, all]. In preadipocytes, omentin 1 release was 1.28-fold increased by FGF-21 (p < 0.05). In adipocytes, FGF-21 reduced chemerin release by 5% and enhanced DPP4 release by 1.15-fold (p < 0.05, both). FGF-21 altered the expression of four secretory genes in preadipocytes and of 18 in adipocytes (p < 0.01, all). CONCLUSION: The hepatokine FGF-21 exerts secretome-modulating effects in human perivascular (pre)adipocytes establishing a new liver-PVAT-blood vessel axis that possibly contributes to vascular inflammation and atherosclerosis.

Functional characterization of intracellular pH regulators responsible for acid extrusion in human radial artery smooth muscle cells.

Intracellular pH (pHi) is a critical factor influencing many important cellular functions. Acid extrusion carriers such as an Na⁺/H⁺ exchanger (NHE) Na⁺/HCO3⁻ cotransporter (NBC) and monocarboxylate transporters (MCT) can be activated when cells are in an acidic condition (pHi < 7.1). Human radial artery smooth muscle cells (HRASMC) is an important conduit in coronary artery bypass graft surgery. However, such far, the pHi regulators have not been characterized in HRASMCs. We therefore investigated the mechanism of pHi recovery from intracellular acidosis and alkalosis, induced by NH4Cl-prepulse and Na-acetate-prepulse, respectively, using intracellular 2',7'-bis(2-carboxethyl)-5(6)- carboxy-fluorescein (BCECF)-fluorescence in HRASMCs. Cultured HRASMCs were derived from the segments of human radial artery that were obtained from patients undergoing bypass grafting. The resting pHi is 7.22 ± 0.03 and 7.17 ± 0.02 for HEPES- (nominally HCO3⁻-free) and CO2/HCO3⁻- buffered solution, respectively. In HEPES-buffered solution, a pHi recovery from induced intracellular acidosis could be blocked completely by 30 µM HOE 694 (3-methylsulfonyl-4-piperidinobenzoyl, guanidine hydrochloride) a specific NHE inhibitor, or by removing [Na⁺]0. In 3% CO2/HCO3⁻-buffered solution, HOE 694 slowed the pHi recovery from the induced intracellular acidosis only, while adding together with DIDS (a specific NBC inhibitor) or removal of [Na⁺]0 entirely inhibited the acid extrusion. Moreover, α-cyano-4-hydroxycinnamate (CHC; a specific blocker of MCT) blocked the lactate-induced pHi changes. In conclusion, we demonstrate, for the first time, that 3 different pHi regulators responsible for acid extruding, i.e. NHE and NBC, and MCT, are functionally co-existed in cultured HRASMCs.

Morpho-functional features of the radial artery: implications for use as a coronary bypass conduit.

Since its reintroduction in the early 1990s the radial artery has gained a major role in coronary surgery, currently representing a valid alternative to the right internal thoracic artery as a second arterial graft. However, its peculiar morphologic and functional features have both surgical and clinical critical implications that must be taken into account. In this review we summarize the current totality of evidence on the biologic characteristics of the radial artery, such as its histopathology, vasoreactivity, and remodeling, and discuss their potential implications for use as a coronary bypass conduit.

[The effects of failure of low density lipoprotein receptor expression induced by inflammation on radial artery foam cell formation in patients with end-stage renal disease].

OBJECTIVE: To investigate whether inflammation exacerbates lipid accumulation in the radial arteries of patients with end-stage renal disease (ESRD) and to explore its underlying mechanisms. METHODS: Thirty ESRD patients receiving arteriovenostomy were included. The patients were divided by the plasma level of C-reactive protein into control group (n = 16) and inflamed group (n = 14). Foam cell formation and lipid droplet accumulation were checked by HE staining and Oil red O staining. Tissue inflammation and intracellular cholesterol trafficking correlated proteins were examined by immunohistochemistry or immunofluorescent staining. RESULTS: There were no differences in primary diseases, age, body weight, hemoglobin, total protein, albumin, glucose, lipid profile between the two groups (all P values >0.05). The expressions of tumor necrosis factor α (TNFα) and monocyte chemotactic protein-1 (MCP-1) of the radial artery were increased in the inflamed group. There was significant lipid accumulation in the radial arteries of inflamed group compared to the control group, which was correlated with the increased protein expressions of low density lipoprotein receptor (LDLr), sterol regulatory element binding protein-2 (SREBP-2), and SREBP cleavage-activating protein (SCAP). Confocal microscopy observation showed that inflammation enhanced the translocation of SCAP escorting SREBP-2 from endoplasmic reticulum to Golgi, thereby activating LDLr gene transcription. Further analysis showed that dysregulation of LDLr pathway induced by inflammation was associated with increased protein expression of mTOR (r = 0.733, P < 0.05), especially with the enhanced co-expression of mTOR and SREBP-2(P < 0.05). CONCLUSION: Inflammation accelerates the progression of foam cell formation in ESRD patients via dysregulation of LDLr pathway, which might be partly through the activation of mTOR pathway.

A high red blood cell distribution width predicts failure of arteriovenous fistula.

In hemodialysis patients, a native arteriovenous fistula (AVF) is the preferred form of permanent vascular access. Despite recent improvements, vascular access dysfunction remains an important cause of morbidity in these patients. In this prospective observational cohort study, we evaluated potential risk factors for native AVF dysfunction. We included 68 patients with chronic renal disease stage 5 eligible for AVF construction at the Department of General and Vascular Surgery, Central Clinical Hospital Ministry of Internal Affairs, Warsaw, Poland. Patient characteristics and biochemical parameters associated with increased risk for AVF failure were identified using Cox proportional hazards models. Vessel biopsies were analyzed for inflammatory cells and potential associations with biochemical parameters. In multivariable analysis, independent predictors of AVF dysfunction were the number of white blood cells (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.24 to 2.25; p<0.001), monocyte number (HR 0.02; 95% CI 0.00 to 0.21; p = 0.001), and red blood cell distribution width (RDW) (HR 1.44; 95% CI 1.17 to 1.78; p<0.001). RDW was the only significant factor in receiver operating characteristic curve analysis (area under the curve 0.644; CI 0.51 to 0.76; p = 0.046). RDW>16.2% was associated with a significantly reduced AVF patency frequency 24 months after surgery. Immunohistochemical analysis revealed CD45-positive cells in the artery/vein of 39% of patients and CD68-positive cells in 37%. Patients with CD68-positive cells in the vessels had significantly higher white blood cell count. We conclude that RDW, a readily available laboratory value, is a novel prognostic marker for AVF failure. Further studies are warranted to establish the mechanistic link between high RDW and AVF failure.

[Differences in nitric oxide release and endothelium-derived hyperpolarizing factor-mediated hyperpolarization between human radial artery and saphenous vein].

OBJECTIVE: To compare the differences in nitric oxide (NO) release and endothelium-derived hyperpolarizing factor (EDHF)-mediated hyperpolarization between human radial artery (RA) and saphenous vein (SV) through direct measurement of NO and membrane potential. METHODS: RA (n = 8), SV (n = 23), and surgical prepared SV (PV, n = 9, dilatation with normal saline solution at a pressure of 100 - 600 mmHg, 1 mmHg = 0.133 kPa) segments (5 mm long) taken from patients undergoing coronary artery bypass grafting were placed in an organ chamber. The NO-sensitive electrode and intracellular glass microelectrode was used to directly measure the NO release and the membrane potential changes in response to acetylcholine (ACh) and bradykinin (BK) before and after incubation with NG-nitro-L-arginine, indomethacin, and oxyhemoglobin. RESULTS: The basal release of NO in RA [(11.9 ± 1.8) nmol/L] was significantly greater than that in SV [(9.9 ± 2.8) nmol/L, P = 0.041]. BK-induced NO release in RA was lower than that in SV [for BK 10(-7) mol/L: (25.8 ± 3.6) nmol/L vs. (43.7 ± 8.2) nmol/L, P = 0.006]. Both basal and ACh- or BK-induced NO release in PV were significantly reduced [basal release: PV (3.4 ± 1.4) nmol/L; P = 0.006 vs. RA; P = 0.002 vs. SV; stimulated release: for ACh 10(-5) mol/L: PV (4.8 ± 3.2) nmol/L; vs. RA (28.6 ± 7.9) nmol/L, P = 0.005; vs. SV (27.4 ± 3.7) nmol/L, P = 0.003; for BK 10(-7) mol/L: PV (7.0 ± 3.6) nmol/L; vs. RA (25.8 ± 3.6) nmol/L, P = 0.016; vs. SV (43.7 ± 8.2) nmol/L, P = 0.004]. EDHF-mediated hyperpolarization was greater in RA than that in SV [ACh 10(-5) mol/L: (-9.7 ± 1.9) mV vs. (-4.5 ± 1.1) mV, n = 17, P = 0.002]. CONCLUSIONS: RA is superior to SV in terms of NO basal release and EDHF-mediated endothelial function. Surgical preparation and pressure dilatation may severely impair the NO-mediated endothelial function of SV, which may contribute to the poor long-term patency of SV coronary graft.

Angioplastia coronária nas indicações off-label: comparação das vias radial vs. femoral / Coronary angioplasty in off-label indications: comparison of radial vs. femoral approach

Introdução: A via radial é objeto de interesse crescente para procedimentos diagnósticos e terapêuticos por possuir diversas vantagens, entre as quais comodidade para o paciente no pós-procedimento imediato, com retorno precoce a suas atividades, diminuição do tempo de internação, com consequente redução dos custos hospitalares, e baixo índice de complicação do sítio de punção comparativamente à via femoral, reduzindo a taxa de sangramento maior, que, por sua vez, está relacionada ao aumento do risco de morte e eventos isquêmicos. Método: Análise retrospectiva de 1.807 pacientes consecutivos submetidos a angioplastia coronária percutânea (ATC) off-label entre setembro de 2006 e dezembro de 2009. Comparamos os pacientes submetidos a ATC pelas vias radial e femoral em relação às evoluções hospitalar e tardia. Resultados: Predominaram na via radial pacientes mais jovens, do sexo masculino, com menor complexidade angiográfica, fato que se deveu à curva de aprendizado. Houve menor taxa de eventos cardíacos adversos maiores (ECAM), óbito e revascularização do vasoalvo na via radial, tanto na fase hospitalar como na fase tardia, em virtude do perfil clínico-angiográfico mais favorável. A via femoral foi preditor independente de ECAM hospitalar. A curva de sobrevivência ajustada, no entanto, mostrou que a via de acesso não teve influência significativa nos eventos clínicos a longo prazo. Conclusão: A técnica radial é segura na abordagem de pacientes selecionados com indicação off-label, apresentando resultados clínicos satisfatórios nas evoluções inicial e tardia.

Background: There is increasing interest in the use of the radial approach in diagnostic and therapeutic proceduresdue to several advantages such as patient comfort in the immediate post-procedure with early return to daily routine activities, decreased hospitalization time and consequentreduction of hospital costs and low puncture site complication rates when compared with the femoral approach, reducing the rate of major bleeding, which is in turn related to increased risk of death and ischemic events. Method:Retrospective analysis of 1,807 consecutive patients undergoingoff-label percutaneous transluminal coronary angioplasty (PTCA) from September 2006 to December 2009.The outcome of patients undergoing PTCA using the radial and femoral approaches during hospitalization and late follow-up were compared. Results: The radial approach prevailed in younger, male patients with lower angiographic complexity, which was due to the learning curve. Major adverse cardiac events (MACE), death and target-vessel revascularization rates were lower when the radial approachwas used, both during hospitalization and in the late follow-up due to a more favorable clinical-angiographic profile.The femoral approach was an independent predictor of hospital MACE. The adjusted survival curve, however,showed that the access route did not have a significant impact on long-term clinical events. Conclusion: Thetransradial approach is safe when used in selected patients with off-label indication, providing good clinical results in the early and late follow-up.

Vasorelaxing action of vasonatrin peptide is associated with activation of large-conductance Ca(2+)-activated potassium channels in vascular smooth muscle cells.

The aim of this study was to test the hypothesis that vasorelaxing action of vasonatrin peptide (VNP) is due to activation of the large-conductance Ca(2+)-activated potassium channel (BK(Ca)) via guanylyl cyclase (GC)-coupled natriuretic peptide receptors (NPRs) in vascular smooth muscle cells (VSMCs). Contraction experiments were performed using human radial artery, whereas BK(Ca) current by patch clamp was recorded in cells from rat mesenteric artery. Contractility of rings cut from human radial artery was detected in vitro. As a result, VNP induced a dose-dependent vasorelaxation of human radial artery, which could be mimicked by 8-Br-cGMP, and suppressed by TEA, a blocker of BK(Ca), HS-142-1, a blocker of GC-coupled NPRs, or methylene blue (MB), a selective inhibitor of guanylyl cyclase. Sequentially, whole-cell K(+) currents were recorded using patch clamp techniques. BK(Ca) current of VSMCs isolated from rat mesentery artery was obtained by subtracting the whole cell currents after applications of 10(-7) mol/l iberiotoxin (IBX) from before its applications. In accordance with the results of arterial tension detection, BK(Ca) current was significantly magnified by VNP, which could also be mimicked by 8-Br-cGMP, whereas suppressed by HS-142-1, or MB. Taken together, VNP acts as a potent vasodilator, and NPRA/B-cGMP-BK(Ca) is one possible signaling system involved in VNP induced relaxation.

ACE2 and AT4R are present in diseased human blood vessels.

A growing body of evidence suggests that the angiotensin II fragments, Ang(1-7) and Ang(3-8), have a vasoactive role, however ACE2, the enzyme that produces Ang(1-7), or AT4R, the receptor that binds Ang (3-8), have yet been simultaneously localised in both normal and diseased human conduit blood vessels. We sought to determine the immunohistochemical distribution of ACE2 and the AT4R in human internal mammary and radial arteries from patients undergoing coronary artery bypass surgery. We found that ACE2 positive cells were abundant in both normal and diseased vessels, being present in neo-intima and in media. ACE2 positive immunoreactivity was not present in the endothelial layer of the conduit vessels, but was clearly evident in small newly formed angiogenic vessels as well as the vaso vasorum. Endothelial AT4R immunoreactivity were rarely observed in either normal and diseased arteries, but AT4R positive cells were observed adjacent to the internal elastic lamine in the internal mammary artery, in the neo-intima of radial arteries, as well as in the media of both internal mammary artery and radial artery. AT4R was abundant in vaso vasorum and within small angiogenic vessels. Both AT4R and ACE2 co-localised with smooth muscle cell alpha actin. This study identifies smooth muscle cell alpha actin positive ACE2 and AT4R in human blood vessels as well as in angiogenic vessels, indicating a possible role for these enzymes in pathological disease.

Antithrombin III metabolism in the pulmonary vessel endothelium.

In 85 patients undergoing aorto-coronary bypass for atherosclerotic coronary disease, we measured the antithrombin III activity levels and the thrombin-antithrombin III complex concentrations in blood from the pulmonary and the radial arteries, taken before the aorto-coronary bypass procedure, with the aim of investigating the role of the pulmonary endothelium in the metabolism of the inhibitor. Results showed significantly lower mean antithrombin III activity levels, expressed as a percentage of normal plasma, in blood from the radial artery with respect to levels from the pulmonary artery (0.78 +/- 0.12 versus 0.80 +/- 0.12, P<0.0001), while no significant difference was found in thrombin-antithrombin III complex concentrations. The results seem to show that the pulmonary endothelium contributes to the antithrombin III metabolism with a 0.023 breakdown rate, corresponding to about a 0.1 fraction of the reported 0.22-0.25 total body catabolic rate, as well as the pulmonary endothelial surface (50-70 m2) corresponding to about a 0.1 fraction of the peripheral vessels' endothelial surface (500-700 m2). The data support the hypothesis of a main endothelial catabolism of antithrombin III.

Expression and localization of C-type natriuretic peptide in human vascular smooth muscle cells.

OBJECTIVES: C-type natriuretic peptide (CNP) released by vascular endothelium relaxes smooth muscle and is important in the maintenance of vascular tone. Since it is not known whether other human vascular cell types produce CNP, we investigated its expression in human vascular smooth muscle. METHODS: CNP expression was examined by RT-PCR in vascular smooth muscle cells (SMC) cultured from human saphenous vein (SV), internal mammary artery (IMA) and radial artery (RA), and CNP protein was probed using immunostaining, in tissue sections and in SMCs cultured from these vessels, respectively. RESULTS: PCR for CNP produced a 334 bp product in all SMC cultures, as expressed in endothelial cells, although the band intensity was markedly less in SMCs. Myocardium from CNP-knockout mouse did not express CNP, while there was expression in wild-type mouse. CNP protein was detected by immunostaining in 100% of SMC cultures. By immunostaining of tissue sections, CNP was detected throughout the medial layer, but not adventitia, of all vessel types. CONCLUSIONS: Expression of CNP at gene and protein level by human vascular SMCs suggests that CNP may have the capacity to regulate vascular tone independently of the endothelium.

Radial artery as an autologous cell source for valvular tissue engineering efforts.

To create a viable tissue-engineered aortic valve, it is important to identify suitable autologous cell sources that may be seeded onto a biocompatible scaffold. This study focused on the radial artery (RA) as one possible source, investigated optimal culture conditions, and determined the usefulness of small intestinal submucosa (SIS) as a scaffold for tissue-engineering. Porcine RA cells were cultured on either two-dimensional (2D) 100-mm dishes or three-dimensional (3D) 1-cm(2) SIS sheets, producing cell-scaffold composites (CSCs). Both 2D and 3D cultures were maintained in either Medium 199 (M199) or endothelial growth media (EGM) to determine optimal growth conditions. Cellular phenotype and matrix metalloproteinase (MMP) profiles were determined by immunoblotting of cell lysates and zymography of conditioned media, respectively. Cellular invasion was analyzed immunohistochemically on CSC tissue sections. We show that the RA contains phenotypes consistent with those found in the normal aortic valve. EGM, compared with M199, promotes the invasion and remodeling of SIS by RA cells, which is crucial in the process of replacing the foreign tissue scaffold prior to implantation. To our knowledge, this is the first study to show that the RA is a suitable source for the generation of a tissue-engineered valve.

Vascular-wall remodeling of 3 human bypass vessels: organ culture and smooth muscle cell properties.

OBJECTIVES: Late graft occlusions after coronary artery bypass grafting have been ascribed to neointimal hyperplasia. Given the pivotal role of smooth muscle cells in the pathogenesis of neointimal hyperplasia and the phenotypic heterogeneity of smooth muscle cells across vessels, we hypothesized that differences in long-term graft patency are at least partly related to differences in smooth muscle cell properties. The aim of the present study was to compare the vascular-wall remodeling of human internal thoracic artery, radial artery, and saphenous vein bypass conduits. METHODS: We evaluated the intimal thickening of the human graft segments in organ cultures (histopathology, morphometric, and immunofluorescence analyses) and assessed the properties of cultured smooth muscle cells isolated from these vessels in terms of cell proliferation (tritiated thymidine incorporation), migration (modified Boyden chamber), and collagen synthesis (tritiated proline incorporation). RESULTS: The total vessel-wall growth index and the intimal growth index were significantly higher for saphenous vein rings than for radial artery and internal thoracic artery rings. Immunofluorescence analyses showed predominant involvement of smooth muscle cells in neointimal growth induced by organ culture of saphenous vein rings. Cell proliferation was significantly higher in saphenous vein smooth muscle cells than in radial artery smooth muscle cells and significantly higher in radial artery smooth muscle cells than in internal thoracic artery smooth muscle cells. Migration of smooth muscle cells from saphenous vein grafts was significantly greater than from internal thoracic artery or radial artery grafts. Collagen synthesis was similar in smooth muscle cells from internal thoracic artery, radial artery, and saphenous vein grafts. CONCLUSIONS: Ex vivo vascular-wall remodeling and smooth muscle cell intrinsic growth and migratory properties are dissimilar between arterial and venous grafts and might shed light on reported angiographic patency rates of these grafts.

Endoscopic versus conventional radial artery harvest for coronary artery bypass grafting: functional and histologic assessment of the conduit.

BACKGROUND: The radial artery's propensity for vasospasm and vulnerability to surgical trauma are well known. A less invasive endoscopic method to harvest the radial artery was recently introduced, but its effect on radial artery integrity is unknown. METHODS: To compare the effects of harvest method on radial artery function, we prospectively randomized 54 patients undergoing coronary artery bypass grafting with the radial artery into 3 groups on the basis of harvest techniques: endoscopic, conventional with cautery, and conventional with harmonic scalpel. We assessed endothelium-dependent and endothelium-independent relaxation of radial artery segments to sequential doses of acetylcholine and nitroglycerin, respectively, using standard organ-chamber methodology. Vasospasm was assessed as the vasoconstrictor response to the thromboxane analog U46619. We assessed endothelial integrity using light and electron microscopy and by rating intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and P-selectin expression by means of immunohistochemistry on a semiquantitative 0- to 3-point scale. Harvest procedures were performed by a single surgeon, and data analyses were blinded to the harvesting method. RESULTS: Maximal relaxation-contraction responses to acetylcholine, nitroglycerin, and U46619 and effective drug concentration yielding 50% response were similar in the 3 groups. Adhesion molecule expression and histologic changes, as assessed by means of light and electron microscopy, were similar in the 3 groups. CONCLUSIONS: Endoscopic harvest does not alter radial artery vasoreactivity or endothelial integrity compared with conventional harvest techniques. Because the endoscopic technique is less invasive, it might prove to be the technique of choice to harvest the radial artery.

Glycated and carboxy-methylated proteins do not directly activate human vascular smooth muscle cells.

BACKGROUND: Advanced glycation end products (AGEs) accumulate in patients with diabetes, particularly at sites of vascular damage and within atherosclerotic lesions, but whether they have direct actions on vascular smooth muscle cells (VSMCs) is controversial. METHODS: AGEs were constructed and characterized by protein content, level of modification, fluorescence, and molecular size. Human VSMCs were derived from different vascular beds. Glucose consumption, de novo protein synthesis, and proteoglycan biosynthesis were measured using a colorimetric assay and metabolic radiolabeling. Receptor for AGEs (RAGE) expression was assessed by real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. RESULTS: Treatment with AGEs under low or high glucose conditions showed no change in cellular glucose consumption or in cellular protein synthesis under low glucose conditions. Treatment of VSMCs with Nepsilon-(carboxymethyl)lysine in the presence of low glucose increased [35S]-sulfate incorporation into secreted proteoglycans by 72% (P < 0.001) and 67% (P < 0.001); however, the control proteins also increased [35S]-sulfate incorporation into proteoglycans by 56% (P < 0.01), with similar effects observed under high glucose conditions. Human VSMCs showed no difference in response to glycated and non-glycated protein. Protein and gene expression of RAGE in VSMC was approximately 50-fold lower compared to HMEC-1 and U937 cells, consistent with the immunohistochemical staining of RAGE in vivo. CONCLUSION: VSMCs show very low levels of RAGE expression; thus, activation of VSMCs by AGEs does not occur. In diabetes, RAGE expression in VSM may increase to the extent that it becomes activated by AGEs in a manner that would contribute to the process of atherosclerosis.

Inhibitory activity of clinical thiazolidinedione peroxisome proliferator activating receptor-gamma ligands toward internal mammary artery, radial artery, and saphenous vein smooth muscle cell proliferation.

BACKGROUND: The proliferation of vascular smooth muscle cells (VSMCs) is a known response to arterial injury that is an important part of the process of restenosis and atherosclerosis. People with diabetes have an increased risk of cardiovascular disease resulting from accelerated coronary atherosclerosis. The newest drugs for Type 2 diabetes are thiazolidinediones, which are insulin-sensitizing peroxisome proliferator activating receptor-gamma (PPARgamma) ligands. We investigated the antiproliferative effects of troglitazone, rosiglitazone, and pioglitazone on VSMCs derived from the three vascular beds used for coronary artery by-pass grafting: the internal mammary and radial artery and saphenous veins. METHODS AND RESULTS: The three vessels yielded proliferating cells of slightly differing morphology. Inhibition of cell proliferation was assessed by cell counting and cell cycle studies by Western blotting for phosphorylated retinoblastoma protein. All three thiazolidinediones showed inhibitory potency toward cell proliferation with a potency troglitazone>rosiglitazone approximately pioglitazone, and this potency profile was maintained toward the growth factor and insulin-stimulated phosphorylation of the retinoblastoma protein, which controls cell cycle progression. CONCLUSIONS: The inhibitory potency of clinical thiazolidinediones toward different vascular sources is dependent on the individual thiazolidinedione and very little on the vascular source.

Effect of cyclic axial stretch of rat arteries on endothelial cytoskeletal morphology and vascular reactivity.

Pulsatile fluid shear stress and circumferential stretch are responsible for the axial alignment of vascular endothelial cells and their actin stress fibers in vivo. We studied the effect of cyclic alterations in axial stretch independent of flow on endothelial cytoskeletal organization in intact arteries and determined if functional alterations accompanied morphologic alterations. Rat renal arteries were axially stretched (20%, 0.5 Hz) around their in vivo lengths, for up to 4h. Actin stress fibers were examined by immunofluorescent staining. We found that cyclic axial stretching of intact vessels under normal transmural pressure in the absence of shear stress induces within a few hours realignment of endothelial actin stress fibers toward the circumferential direction. Concomitant with this morphologic alteration, the sensitivity (log(EC(50))) to the endothelium-dependent vasodilator (acetylcholine) was significantly decreased in the stretched vessels (after stretching -5.15+/-0.79 and before stretching -6.71+/-0.78, resp.), while there was no difference in sodium nitroprusside (SNP) sensitivity. There was no difference in sensitivity to both acetylcholine and SNP in time control vessels. Similar to cultured cells, endothelial cells in intact vessels subjected to cyclic stretching reorganize their actin filaments almost perpendicular to the stretching direction. Accompanying this morphological alteration is a loss of endothelium-dependent vasodilation but not of smooth muscle responsiveness.

Purinergic receptor distribution in endothelial cells in blood vessels: a basis for selection of coronary artery grafts.

Expression levels of the purinergic P2X receptor subunits (P2X(1) to P2X(7)) and P2Y(2) were examined in the endothelial cell layer of internal mammary artery (Ann. Thorac. Surg. 54 (1992) 652), radial artery (Ann. Thorac. Surg. 16 (1973) 111) and saphenous vein (Ann. Thorac. Surg. 20 (1975) 628) samples obtained at surgery for coronary artery bypass grafts using immunohistochemistry and confocal microscopy. Similar levels of P2X(1), P2X(2), P2X(3), P2X(7) and P2Y(2) were found in the endothelial cells in all vessels examined while the levels of P2X(5) and P2X(6) were uniformly lower. A clear difference was measured in P2X(4) expression between arteries and veins. Both radial and internal mammary arteries exhibited very low levels of P2X(4) whereas the level in the saphenous vein was 14.6 fold higher (P<0.0001), approaching that of the major receptor subtypes. These data showing strong expression of P2X(4) in veins have implications for the choice of vessels used in coronary artery bypass grafts given that P2X(4) is involved in calcium influx into endothelial cells, modulates blood vessel contractility and is up-regulated in situations involving intima proliferation suggesting vein grafts are more susceptible to developing atherosclerosis.