Carotid Arterial Stiffness in Patients with Congenital Heart Disease-Related Pulmonary Hypertension Assessed with Radio Frequency Data Technique.

BACKGROUND: It has been well known that pulmonary hypertension (PH) caused by congenital heart disease (CHD) leads to reduced flexibility of the small pulmonary arteries, due to hemodynamic changes in the pulmonary circulation and alterations of the vasoactive profile. However, whether CHD-related PH affects the elasticity of the systemic arteries, such as the common carotid artery (CCA), has not been fully investigated. The purpose of this study was to explore the CCA stiffness in patients with CHD-related PH using the radio frequency data technique. METHODS: Forty patients with CHD were included. They were divided into PH and non-PH (NPH) groups by the right heart catheter-determined or regurgitation velocity-determined mean pulmonary arterial pressure (mPAP). MyLabTwice (Esaote, Genoa, Italy) ultrasound machine equipped with automatic quality intima-media thickness (QIMT) and quality arterial stiffness (QAS) capabilities was used to measure the left common carotid arterial (CCA) intima-media thickness and arterial stiffness parameters. RESULTS: The results have shown that the left CCA internal diameter, pulse wave velocity, arterial wall tension, and local diastolic pressure were increased in the CHD-related PH group compared with the CHD-related NPH group (all P < 0.05). The left CCA internal diameter negatively and significantly correlated with the mean PAP. CONCLUSIONS: Common carotid artery diameter and stiffness increase in patients with CHD-related pulmonary hypertension. QIMT and QAS ultrasound techniques may provide a comprehensive assessment of the CCA remodeling.

Serum omentin-1 levels are inversely associated with the presence and severity of coronary artery disease in patients with metabolic syndrome.

CONTEXT: Omentin-1, an adipokine secreted from visceral adipose tissue, has been reported to be associated with coronary artery disease (CAD) and metabolic disorders. OBJECTIVE: To clarify the relationship between serum omentin-1 levels and the presence and severity of CAD in patients with metabolic syndrome (MetS). METHODS: We measured serum omentin-1 levels in 175 consecutive patients with MetS and in 46 controls. RESULTS: Serum omentin-1 levels are inversely associated with the presence and angiographic severity of CAD in MetS patients. CONCLUSIONS: Serum omentin-1 might be a potential biomarker to predict the development and progression of CAD in MetS patients.

Analysis of Doppler flow spectra of the superior vena cava in a canine model of acute thromboembolic pulmonary hypertension.

We aimed to establish a canine model of acute thromboembolic pulmonary hypertension (ATEPH) and to explore the feasibility of diagnosing pulmonary hypertension (PH) through the Doppler flow spectra of the superior vena cava (SVC). A canine model of ATEPH was developed by infusing thrombus into the right femoral vein. The pulmonary arterial pressure was simultaneously measured via a right heart catheter with the guidance of ultrasound. The maximum systolic peak flow velocity (SPV), ventricular reverse peak flow velocity (VRPV), diastolic peak flow velocity (DPV), and atrial reverse peak flow velocity (ARPV) of the SVC were measured by transthoracic echocardiography. ATEPH was successfully established in 24 dogs (88.9%) with the pulmonary arterial systolic pressure (PASP) greater than 30 mmHg. ARPV increased significantly with the increase of PASP, and was positively correlated with PASP (P<0.001). The ARPV/SPV larger than 0.8 could be better adopted to identify all the subjects with PH in this study. The Doppler flow spectra of the SVC could be employed to assess the severity of ATEPH.

Effects of autoantibodies against M2 muscarinic acetylcholine receptors on rabbit atria in vivo.

BACKGROUND: Evidence has shown that autoantibodies against M2 muscarinic acetylcholine receptors may play a role in the development of atrial fibrillation. The goal of this study was to evaluate the effects of anti-M2 receptor autoantibodies on rabbit atria in vivo. METHODS: Rabbits were immunized monthly with a synthetic peptide corresponding to the M2 receptor. The atrial electrophysiology of the isolated perfused rabbit hearts was studied. Western blots and RT-PCR were performed to determine the expression of the atrial muscarinic receptor and the acetylcholine-activated potassium channel. Atrial tissue was stained with Masson's trichrome stain for fibrosis detection. RESULTS: Autoantibodies were persistently detected in immunized rabbits. M2 rabbits showed a significantly shorter atrial effective refractory period and a longer intra-atrial activation time than control rabbits. Electrical stimuli induced a significantly larger number of repetitive atrial responses in M2 rabbits. The protein levels of the M2 receptor and GIRK4 were upregulated in M2 rabbits. The mRNA levels of GIRK1 and GIRK4 were also upregulated. Histological examination revealed significantly increased diffuse fibrotic deposition in M2 rabbit atria compared with control rabbits. CONCLUSION: The M2 receptor autoantibody-positive rabbits showed altered atrial electrophysiology, overexpression of the M2 receptor-I(K,ACh) pathway and atrial fibrosis, which indicates that the autoantibodies against M2 receptors may participate in the induction and perpetuation of atrial fibrillation.

Inhibitory effect of cyclosporin A on growth and collagen synthesis of rat cardiac fibroblasts induced by arginine vasopressin.

AIM: To investigate the effects of cyclosporin A (CsA) on growth and collagen synthesis of cardiac fibroblasts (CFs) induced by arginine vasopressin (AVP). METHODS: CFs of neonatal Sprague-Dawley rats were isolated by trypsinization and cultured; growth-arrested CFs were stimulated with 1 x 10(-7) mol x L(-1) AVP in the presence or absence of CsA (0.05, 0.5 and 5 micromol x L(-1)). MTT and flow cytometry techniques were adopted to measure cell number and analyze cell cycle respectively. Collagen synthesis was determined by measurement of hydroxyproline content in culture supernatant with colorimetry. Calcineurin activity was estimated by chemiluminescence. Trypan blue staining to test the viability of CFs. RESULTS: 0.05, 0.5 and 5 micromol x L(-1) CsA inhibited the increase of CFs number induced by 1 x 10(-7) mol x L(-1) AVP in a dose-dependent manner, with the inhibitory rates by 12%, 24% and 29%, respectively (P < 0.05). Furthermore, cell cycle analysis showed 0.5 micromol x L(-1) CsA decreased the S stage percentage and proliferation index of CFs stimulated by AVP (P < 0.05). In culture medium, the hydroxyproline content induced by AVP decreased by 0.5 and 5 micromol x L(-1) CsA (P < 0.05), with the inhibitory rates of 29% and 33%, respectively. CsA completely inhibited the increment of calcineurin activity induced by AVP (P < 0.01), but CsA itself had no effect on the baseline of calcineurin activity and CFs viability. CONCLUSION: CsA inhibits proliferation and collagen synthesis of CFs by virtue of blocking calcineurin signaling pathway and might provide a novel target for prevention and treatment to cardiac fibrosis.

Clinical Application of Superior Vena Cava Spectra in Evaluation of Pulmonary Hypertension: A Comparative Echocardiography and Catheterization Study.

This study was designed to assess whether superior vena cava (SVC) Doppler flow velocities are associated with invasive measures of pulmonary arterial pressure. Eighty patients with unrepaired congenital heart disease who underwent cardiac catheterization were included (31 men, 49 women; mean age: 37.3 ± 14.7 y). Compared with the non-pulmonary hypertension group, the moderate and severe pulmonary hypertension groups had decreased SVC ventricular reserve flow velocity and a significantly increased ratio of atrial reverse flow to systolic flow (AR/S). AR/S correlated significantly with invasive pulmonary arterial systolic pressure (r = 0.426, p < 0.0001). A cutoff of 0.45 had a sensitivity and specificity of 74% and 80%, respectively, for prediction of pulmonary hypertension. Good correlation also existed between SVC AR/S and pulmonary arterial systolic pressure in cases without tricuspid regurgitation (r = 0.706, p = 0.034). These results indicate that SVC AR/S may be an alternative method for assessing pulmonary hypertension.

[Effects of simvastatin on the left ventricular hypertrophy in spontaneously hypertensive rats and its relationship with the expression of protein kinase B].

OBJECTIVE: To investigate the effects of simvastatin on left ventricular hypertrophy (LVH) in spontaneously hypertensive rats (SHRs) and its possible mechanism. METHODS: Sixteen male SHRs were randomly divided into 2 equal groups: treatment group and SHR control to be given simvastatin or glucose-normal saline by oral gavage for 10 weeks. Eight Wistar-Kyoto (WKY) rats were given normal saline as normal controls. Blood pressure was measured before the experiment and then once every week after the beginning of experiment. By the end of the experiment the rats were killed and their hearts were taken out to measure the left ventricle weight/body weight. RT-PCR was used to detect the mRNA expression of atrial natriuretic peptide (ANP) and of protein kinase B (PKB) in myocardium. Western blotting was used to examine the protein expression of PKB. RESULTS: (1) The systolic blood pressure of the SHR normal control and treatment groups were 221 mm Hg +/- 10 mm Hg and 217 mm Hg +/- 8 mm Hg respectively (P > 0.05) and the systolic pressure of the normal control group was 126 +/- 6 mm Hg, significantly lower than those of the 2 SHR groups (both P < 0.01). (2) The LVW/BW values of the SHR control group were 3.04 mg/g +/- 0.12 mg/g, 3.73 mg/g +/- 0.08 mg/g, and 4.10 mg/g +/- 0.13 mg/g in the normal control group, SHR treatment group and SHR control group respectively with significant difference between any 2 groups (all P < 0.01). (3) The mRNA expression levels of ANP were 0.44 +/- 0.33, 0.27 +/- 0.03, and 0.17 +/- 0.33 in the SHR control group, SHR treatment group, and normal control group respectively (P < 0.01 or P < 0.05). (4) The mRNA expression levels of PKB were 0.45 +/- 0.05, 0.32 +/- 0.03, and 0.19 +/- 0.02 in the SHR control group, SHR treatment group, and normal control group respectively (P < 0.01 or P < 0.05). CONCLUSION: Simvastatin reverses LVH and myocyte phenocyte transformation in the SHRs with the possible mechanism of decreasing the expression level of PKB.

[The relationship between reactive oxygen species-dependent activation of p38 MAPK and the expression of tumor necrosis factor-α in cultured cardiomyocytes].

AIM: To investigate the role of p38 mitogen-activated protein kinase(MAPK) in lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) expression in neonatal rat cardiomyocytes and to determine the relationship between reactive oxygen species (ROS) and p38 MAPK activation. METHODS: Cardiomyocytes were isolated from neonatal Sprague-Dawley rats and cultured by differential adhesion. Expression of TNF-α was determined in culture medium by ELISA. Activation of p38 MAPK was determined by Western blot analysis with phospho-specific antibody. ROS generation in cardiomyocytes was determined by peroxide specific probe 2', 7'-dichlorofluorescin diacetate (DCF-DA). RESULTS: In cardiomyocytes stimulated with LPS, the content of TNF-α in culture medium correlated with the activity of p38 MAPK in a time-dependent manner. The activation of p38 was observed after stimulation of 1 mg/L LPS for 1 h. TNF-α accumulated significantly in culture medium at 3 h after stimulation of LPS (P<0.05), which was remarkably attenuated by pretreatment with p38 MAPK specific inhibitor SB203580 (P<0.01). Furthermore, the production of ROS in cardiomyocytes stimulated with LPS was also increased at 1 h after stimulation of LPS, consistent with p38 MAPK activity. Pretreatment with antioxidants such as N-acetylcysteine and diphenyleneiodonium significantly inhibited the activation of p38 MAPK compared with LPS control (P<0.05). There was no significance in the activity of p38 MAPK among antioxidants pretreatment and non-LPS control groups. CONCLUSION: The activation of p38 MAPK plays an important role in TNF-α expression in LPS-stimulated cardiomyocytes and the increase of ROS production is prerequisite for the activation of p38 MAPK.

Age-related changes in the atrial muscarinic type 2 receptor and their effects on atrial fibrillation vulnerability in rabbits.

Aging plays an important role in increased vulnerability to atrial fibrillation (AF). Mediated by activity at the muscarinic type 2 receptor (M2R), the parasympathetic nerve contributes to the onset of AF. The purpose of this study was to investigate whether aging changes the distribution of M2R in the atrial myocardium and to determine the impact of these changes on AF vulnerability. Expression of M2R in the atrial myocardium was evaluated by immunostaining and Western blot in three groups-young (3 months old), mature (8 months old) and senescent (36-48 months old) rabbits. AF inducibility was recorded with and without cervical vagal stimulation (VS) in vivo in all groups. AF inducibility, the atrial effective refractory period (AERP) and the monophasic action potential (MAP) were recorded in an additional seven senescent rabbits before and after topical administration of tropicamide. The results showed that the density of M2R in the left atrial free wall (LAFW) was significantly higher than that in other parts of the atria. The left atrial appendage had a higher level of M2R expression than the right atrium. The M2R density of the epicardial side was greater than that of endocardial side in both atria. The senescent group had a significant increase in M2R expression in the LAFW relative to the mature group. AF inducibility was also higher in the senescent group than in the other two groups. After tropicamide administration in the senescent rabbits, AF inducibility decreased significantly, the VS-induced decrease in AERP and MAP duration at 90% repolarization (MAPD90) of LAFW was attenuated, and the dispersion of the AERP and MAPD90 increase was attenuated. In conclusion, our results suggested that there is spatial heterogeneity in the M2R distribution in the atria of the rabbit. The density of M2R in the LAFW increased with the aging of rabbits. This change in M2R enhanced the heterogeneity of the M2R distribution and contributed to the change in age-related AF vulnerability.

Chymase induces profibrotic response via transforming growth factor-beta 1/Smad activation in rat cardiac fibroblasts.

Mast cell-derived chymase is implicated in myocardial fibrosis (MF), but the underlying mechanism of intracellular signaling remains unclear. Transforming growth factor-beta 1 (TGF-beta1) is identified as the most important profibrotic cytokine, and Smad proteins are essential, but not exclusive downstream components of TGF-beta 1 signaling. Moreover, novel evidence indicates that there is a cross talk between Smad and mitogen-activated protein kinase (MAPK) signaling cascade. We investigated whether chymase activated TGF-beta 1/Smad pathway and its potential role in MF by evaluating cardiac fibroblasts (CFs) proliferation and collagen synthesis in neonatal rats. MTT assay and 3H-Proline incorporation revealed that chymase induced CFs proliferation and collagen synthesis in a dose-dependent manner. RT-PCR and Western blot assay demonstrated that chymase not only increased TGF-beta1 expression but also upregulated phosphorylated-Smad2/3 protein. Furthermore, pretreatment with TGF-beta 1 neutralizing antibody suppressed chymase-induced cell growth, collagen production, and Smad activation. In contrast, the blockade of angiotensin II receptor had no effects on chymase-induced production of TGF-beta 1 and profibrotic action. Additionally, the inhibition of MAPK signaling had no effect on Smad activation elicited by chymase. These results suggest that chymase can promote CFs proliferation and collagen synthesis via TGF-beta 1/Smad pathway rather than angiotensin II, which is implicated in the process of MF.

Toll-like receptor 4 siRNA attenuates LPS-induced secretion of inflammatory cytokines and chemokines by macrophages.

Toll-like receptor 4 (TLR4) is critical for activation of macrophages by Lipopolysaccharide (LPS). In this study, we investigated the silencing effects of TLR4-specific 21-nt small interfering RNAs (siRNA) on TLR4 expression in RAW264.7 cells. It was found that treatment with TLR4 siRNA down-regulated the TLR4 mRNA and protein expression in macrophage RAW264.7 cells, and reduced the sensitivity of the cells to LPS stimulation. Our findings also demonstrate that treatment with TLR4 siRNA significantly decreased the tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein 2 (MIP-2) expression induced by LPS. TLR4 siRNA treatment also impaired the signalling of mitogen-activated protein kinases (MAPK) induced by LPS in RAW264.7 cells. These data suggest that inhibition of TLR4 expression by TLR4 siRNA may be therapeutically beneficial in controlling the overall responses of immune cells to LPS.