OBJECTIVETo analyze the expression of angiotensin II (ANG II) receptor and apoptosis in myocardium in rats of endotoxemia.

METHODSModel of endotoxemia was induced by intraperitoneal injection with lipopolysaccharide (LPS) 10 mg/kg in male Wistar rats and saline was injected into control group. The rats were killed at 2 h or 6 h after saline (control) or LPS . Expression of the correlation factors related to apoptosis of Bcl-2, Bax, AT1 and AT2 receptor in myocardial tissue were detected with immunohistochemistry (IHC), and changes of myocardial cells apoptosis was detected by the method of TUNEL. The gene expression of AT1 and AT2 receptor was examined by RT-PCR. The pathological changes of myocardial tissue were observed by electron microscope.

RESULTSCompared with control group , the expression of AT1 and AT2 receptor were significantly decreased, especially in 6 h group; and the expression of Bcl-2 and Bax were decreased, the ratio of Bcl-2/Bax had the downtrend as well as the apoptosis of myocardial cells.

CONCLUSIONInterfered by LPS, the down regulation of AT1 and AT2 receptor expression has the negative relation with apoptosis of myocardial cells, this result indicated that down regulation of AT1 and AT2 receptor expression maybe related to cardiac functional impairment, which maybe help us to find a new protective path to prevent myocardial damage induced by systemic inflammatory.

Animals ; Apoptosis ; Endotoxemia ; metabolism ; Male ; Myocytes, Cardiac ; cytology ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Wistar ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism

OBJECTIVEThe present study was undertaken to observe the expression of angiotensin II (Ang II) type 1 (AT1) and type 2 (AT2) receptors in human hypertrophic scars, and explore their role in the proliferation of fibroblasts in human hypertrophic scars.

METHODSThe expression of both ATL and AT2 receptors in fibroblasts of hypertrophic scars was detected with immunohistochemical staining. Radioligand receptor binding assay and RT-PCR were used to determined expression level of AT1 and AT2 receptors in cultured fibroblasts derived from hypertrophic scars. DNA synthesis was examined in cultured fibroblasts of hypertrophic scars by measuring [3H]-TdR incorporation into fibroblasts.

RESULTSPositive staining signals of both AT1 and AT2 receptors were found in fibroblasts of hypertrophic scars. Expression level of AT1 and AT2 receptors were (10.69 +/- 2.15) fmol/10(6) cells, (4.9 +/- 1.05) fmol/10(6) cells respectively in cultured fibroblasts derived from hypertrophic scars. RT-PCR showed the similar results. In cultured fibroblasts, Ang II stimulation significantly increased DNA synthesis (P < 0.05 vs negative control), which was inhibited by valsartan, an AT1 receptor blocker, but augmented by PD123319, an AT2 receptor antagonist. Valsartan or PD123319 alone did not influence the proliferation of fibroblasts derived from hypertrophic scars.

CONCLUSIONSBoth AT1 and AT2 receptors were expressed in the fibroblasts of hypertrophic scars, and Ang II regulates DNA synthesis in hypertrophic scar fibroblasts through a negative cross-talk between AT1 and AT2 receptors, which might contribute, at least partly to formation and maturation of human hypertrophic scars. The present study provides new insight into pathogenesis of hypertrophic scars.

Cell Proliferation ; Cells, Cultured ; Cicatrix, Hypertrophic ; metabolism ; pathology ; DNA ; biosynthesis ; Fibroblasts ; metabolism ; physiology ; Humans ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism ; Signal Transduction

To investigate the molecular mechanism of angiotensin II (Ang II) receptor activation in adult rat cardiac fibroblasts, the expressions of cell signal transduction-associated genes were studied by using cDNA microarray. Cardiac fibroblasts of adult Sprague-Dawley rats (230~250 g) were isolated and cultured. The cells were divided into 4 groups: Ang II, Ang II + losartan, Ang II + PD123319, Ang II + losartan + PD123319. The expressions of Ang II receptors were studied by immunohistochemical staining. Total RNA was extracted and purified. After cDNA synthesis and biotin-16-dUTP labeling, the probes were denatured and hybridized with GEArray Q Series mouse G Protein-coupled Receptors Signaling Pathway Finder Gene Array (MM-025) containing 96 genes associated with 11 pathways. The arrays were scanned with a Uniscand1000 scanner and further analyzed with GEArray Analyzer software. RT-PCR was used to further confirm the results of gene microarray. The results of immunohistochemical staining showed that the expression of Ang II type 2 (AT2) receptor was evidently induced by Ang II stimulation when Ang II type 1 (AT1) receptor was blocked. The results of gene array indicated that blocking AT1 receptor changed 34 genes (more than 2 folds), 30 were down-regulated and 4 were up-regulated. The maximum change was not beyond 20 folds. The following 9 pathways were activated: cAMP/PKA, Ca2+, PKC, PLC, MAPK, PI-3 kinase, NO-cGMP, Rho, NF-kappaB pathways. Blockade of AT2 receptor caused 64 genes changing more than 2 folds (48 were down-regulated and 16 were up-regulated). Eleven pathways were basically activated. The change of the following 7 genes was over 30 folds: Cyp19a1 (37 folds), Il1r2 (42 folds), Cflar (53 folds), Bcl21 (31 folds), Pik3cg (278 folds), Cdkn1a (90 folds), Agt (162 folds). According to the activated extent, the signal transduction pathways in turn were PI-3 kinase, NF-kappaB and JAK-STAT pathways. Blocking both AT1 and AT2 receptors changed 46 genes more than 2 folds (36 were down-regulated and 10 were up-regulated). Eleven pathways were basically activated. The results of RT-PCR of IL-1beta and TNF-alpha confirmed the observations in gene microarray. Our results show that Ang II can induce a high expression of AT2 receptor in adult rat cardiac fibroblasts when AT1 receptor is blocked, and the signal mechanism of AT2 receptor is clearly different from that of AT1 receptor.
Angiotensin II ; pharmacology ; Angiotensin Receptor Antagonists ; pharmacology ; Animals ; Fibroblasts ; metabolism ; Gene Expression ; Imidazoles ; pharmacology ; Losartan ; pharmacology ; Myocardium ; cytology ; Pyridines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism ; Signal Transduction

OBJECTIVETo explore the role of angiotensin II type 1 (AT1) receptor in activation of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) in lung of mice with LPS-induced acute lung injury (ALI).

METHODSEighty-eight BABL/c mice were divided into control group (n = 8), LPS group (n = 40), and LPS + AT1 receptor antagonist ZD7155 group (n = 40) according to the random number table. Puncture of trachea was done in all mice. Mice in LPS + ZD7155 group were intraperitoneally injected with 10 mg/kg ZD7155. Mice in LPS and control groups were intraperitoneally injected with normal saline in the same volume as that of ZD7155. Thirty minutes later, 1 mg/mL LPS was dripped into trachea of mice in LPS and LPS + ZD7155 groups (2 mg/kg). Normal saline in the same volume as that of LPS was dripped into trachea of mice in control group. Lung tissue samples of mice in LPS and LPS + ZD7155 groups were harvested at post dripping hour (PDH) 1, 3, 6, 12, and 24. Lung tissue sample of mice in control group was harvested at PDH 24. Expression of AT1 receptor was determined with Western blot. AP-1 and NF-kappaB activity in lung tissue was detected with electrophoretic mobility shift assay. Data were processed with one-way analysis of variance.

RESULTSThe relative expression amount of AT1 receptor protein in lung tissue of mice in LPS group at each time point was increased obviously as compared with that of mice in control group (0.69 +/- 0.28, F = 9.356, with P values all below 0.01), and it peaked at PDH 6 (3.44 +/- 0.90), while that of mice in LPS + ZD7155 group was less than that in LPS group at each time point (F = 9.356, with P values all below 0.01). NF-kappaB activity in mice lung was markedly increased in LPS group at each time point as compared with mice in control group (5.47 +/- 0.08, F = 26.443, with P values all below 0.05), and its peak value in LPS group was found at PDH 3 (52.33 +/- 3.25). While NF-kappaB activity in mice of LPS + ZD7155 group was obviously lower than that in LPS group at each time point (F = 26.443, with P values all below 0.05). AP-1 activity in lung was enhanced significantly in LPS group at each time point as compared with that in control group (2.5 +/- 0.4, F = 34.685, with P values all below 0.05), and the activity peaked at PDH 6 (73.3 +/- 9.5) in LPS group. The activity was obviously weaker in mice in LPS + ZD7155 group as compared with that in LPS group at each time point (F = 34.685, with P values all below 0.05).

CONCLUSIONSAT1 receptor contributes to LPS-induced ALI through activating NF-kappaB and AP-1 in lung tissue.

Acute Lung Injury ; metabolism ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Lipopolysaccharides ; pharmacology ; Lung ; pathology ; Male ; Mice ; Mice, Inbred BALB C ; NF-kappa B ; metabolism ; Receptor, Angiotensin, Type 1 ; metabolism ; Transcription Factor AP-1 ; metabolism

Hepatitis B, Chronic ; metabolism ; Humans ; Liver Cirrhosis ; metabolism ; RNA, Messenger ; analysis ; Receptor, Angiotensin, Type 1 ; genetics ; Renin ; genetics

OBJECTIVETo study the effect of angiotensin II on phosphoinositide-3 kinase/Akt cascade in cultured fibroblasts derived from patients with hypertrophic scars.

METHODSThe expression of AT1 and AT2 receptor was detected by immunofluorescence staining. Cultured human skin fibroblasts were treated with Ang II (10(-9) - 10(-7) mol/L), with or without an AT1 receptor blocker, valsartan or an AT2 receptor antagonist, PD123319. The phosphorylation of Akt was detected by western blotting, and PI3K activity was measured by Assay of PI3-K activity.

RESULTSImmunofluorescence staining showed that cultured fibroblasts derived from hypertrophic scars expressed both AT1 and AT2 receptors. Ang II increased Akt phosphorylation and PI3K activity in cultured hypertrophic scar fibroblasts in a dose- and time-dependent manner. Additionally, Ang II-induced Akt phosphorylation was blocked by wortmannin, a PI3-K inhibitor. This Ang II-activated PI3-K/Akt cascade was significantly inhibited by valsartan, an AT1 receptor specific blocker (P<0.05), whereas enhanced by PD123319, an AT2 receptor antagonist (P<0.05).

CONCLUSIONThese results indicate that Ang II receptors regulates PI3-K/Akt cascade of hypertrophic scars fibroblasts via AT1 and AT2.

Angiotensin II ; pharmacology ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Angiotensin II Type 2 Receptor Blockers ; Cells, Cultured ; Cicatrix, Hypertrophic ; metabolism ; pathology ; Fibroblasts ; cytology ; drug effects ; metabolism ; Humans ; Imidazoles ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyridines ; pharmacology ; Receptor, Angiotensin, Type 1 ; Signal Transduction ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

BACKGROUNDAngiotensin II (Ang II) acting at angiotensin AT(1) receptor (AT(1)R) has well documented effects on cardiovascular structure such as the promotion of cardiovascular hypertrophy and fibrosis, which are believed to be opposed by angiotensin AT(2) receptor (AT(2)R) stimulation. The expressions of AT(1)R and AT(2)R are up-regulated in senescent hearts. The purpose of this study was to investigate the interaction of signal transduction between AT(1)R and AT(2)R, and to detect whether there is any difference in the interaction in rat hearts of different age.

METHODSIn 3.5-, 12-, 18- and 24-month-old rats, the heart cell membrane activities of protein kinase C (PKC) and tyrosine kinase were measured when AT(1)R and AT(2)R were both activated by Ang II or just the AT(1)R was activated by Ang II and PD123319. The activities of cytosolic phospholipase A(2) (cPLA(2)) and the levels of cGMP were investigated when AT(1)R and AT(2)R were both activated by Ang II or just the AT(2)R was activated by Ang II and losartan.

RESULTSWhen AT(1)R and AT(2)R were both activated compared to when the AT(1)R was activated, the activities of PKC were not different in hearts from 3.5- and 12-month-old rats, but decreased significantly in 18- and 24-month-old rats; the activities of tyrosine kinase were not different in 3.5-month-old rats but decreased significantly in 12-, 18- and 24-month-old rats. The activities of cPLA(2) were all decreased significantly in rats of different age when AT(1)R and AT(2)R were both activated compared to when the AT(2)R was activated. Treatment with Ang II alone compared to Ang II and losartan decreased the levels of cGMP (fmol/mg) in rats of different age (102.7 +/- 12.7 versus 86.0 +/- 8.0 in 3.5-month-old rats, P < 0.05; 81.0 +/- 9.4 versus 70.0 +/- 6.3 in 12-month-old rats, P < 0.05; 69.8 +/- 5.6 versus 54.2 +/- 5.3 in 18-month-old rats, P < 0.01; 57.7 +/- 8.0 versus 39.0 +/- 3.0 in 24-month-old rats, P < 0.01).

CONCLUSIONSThe activation of AT(1)R inhibited the signal transduction of AT(2)R during the aging variation, and the activation of AT(2)R inhibited the signal transduction of AT(1)R in rat heart of different age.

Aging ; metabolism ; Animals ; Cyclic GMP ; analysis ; Male ; Myocardium ; metabolism ; Phospholipases A2 ; metabolism ; Protein Kinase C ; metabolism ; Protein-Tyrosine Kinases ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; physiology ; Receptor, Angiotensin, Type 2 ; physiology ; Signal Transduction ; physiology

The aim of this study was to observe the change in angiotensin II receptor subtype 1 (AT(1)) autoantibody during the development of renovascular hypertension (RVH). The Goldblatt renovascular hypertension model was established by the two-kidney one-clip method, and a synthetic peptide corresponding to amino acid sequence 165-191 of the second extracellular loop of the AT(1)-receptor was used as the antigen. Sera AT(1)-receptor autoantibody was detected by SA-ELISA. It was shown that two weeks after operation both the frequency of occurrence and the titre of autoantibodies to AT(1)-receptor were significantly increased as compared with the pre-treatment control. The increase in autoantibodies lasted several weeks and then decreased gradually to the pre-clipping level at 12 weeks. It is suggested that autoimmune mechanisms are involved in the pathogenesis of renovascular hypertension and the AT(1) autoantibodies may be one of the mechanisms leading to cardiac hypertrophy.
Animals ; Autoantibodies ; blood ; Disease Models, Animal ; Hypertension, Renovascular ; blood ; immunology ; Kidney ; physiopathology ; Rats ; Receptor, Angiotensin, Type 1 ; immunology ; metabolism

BACKGROUNDVascular smooth muscle cell proliferation is an important process in the development of atherosclerosis and is associated with other cellular processes in atherogenesis. Telmisartan is reported to have partial peroxisome proliferator-activated receptor (PPAR)-γ activating properties and has been referred to as selective PPAR modulators, but valsartan just blocks angiotensin II (AngII) type 1 (AT1) receptors. This study aimed to compare the different effects of telmisartan and valsartan on human aortic smooth muscle cells (HASMCs) proliferation.

METHODSAbility of telmisartan and valsartan to inhibit proliferation of HASMCs was evaluated by the Cell Counting Kit-8 (CCK-8) in continuous cell culture. Whether the antiproliferative effects of telmisartan and valsartan depend on their effects on AngII receptors or activating the peroxisome PPAR-γ was also investigated in this study.

RESULTSTelmisartan inhibited proliferation of HASMCs by 52.4% (P < 0.01) at the concentration of 25 µmol/L and the effect depended on the dose of telmisartan, but valsartan had little effect on HASMCs proliferation (P > 0.05) and no dose response. When tested in cells stimulated with AngII, telmisartan had the same inhibition of HASMCs by 59.2% (P < 0.05) and valsartan also inhibited it by 41.6% (P < 0.05). Telmisartan and valsartan had the same effect on down-regulating AT1 receptor expression and telmisartan was superior to valsartan up-regulating AngII type 2 (AT2) receptor expression. Antiproliferative effects of telmisartan were observed when HASMCs were treated with the PPAR-γ antagonist GW9662 but antiproliferative effects of the PPAR-γ activator pioglitazone were not observed.

CONCLUSIONSTelmisartan, but not valsartan, inhibits HASMCs proliferation and has dose-dependent response without stimulation of AngII. AT2 receptor up-regulation of telmisartan contributes to its greater antiproliferative effects than valsartan. Its PPAR-γ activation does not play a critical role in inhibiting HASMCs proliferation.

Benzimidazoles ; pharmacology ; Benzoates ; pharmacology ; Cell Proliferation ; drug effects ; Humans ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; drug effects ; PPAR gamma ; metabolism ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

BACKGROUNDMany studies have suggested that angiotensin II (Ang II) and its receptors may be involved in the development of asthma. However, the expression of angiotensin II receptors (AGTR) is not clear in the lung tissue of chronic asthmatics. This study was designed to determine the relationship between airway remodeling, dysfunction and the expression of AGTRs in a rat model of asthma.

METHODSRats were sensitized with ovalbumin (OVA) for 2 weeks. Sixty minutes before an inhalation challenge, the rats were pretreated either with valsartan (15, 30, 50 mg x kg(-1) x d(-1)) or saline intragastrically. Then the rats received an OVA challenge for 30 alternative days. Acetylcholine (Ach)-induced bronchoconstriction was measured after the final antigen challenge. White cell counts in bronchoalveolar lavage fluid (BALF) and morphological changes in the airways were then assessed. The levels of transforming growth factor-beta 1 (TGF-beta(1)) and platelet-derived growth factor (PDGF) in BALF were detected by ELISA. The levels of AGTR1 and AGTR2 mRNA and protein in lung tissues were measured by RT-PCR and Western blotting.

RESULTSAGTR1 mRNA and protein levels in repeatedly OVA-challenged rats were significantly increased as compared with negative controls. The AGTR1 mRNA expression versus white cell counts of BALF and airway wall thickness (mainly in small airways) in lungs of chronic antigen-exposed rats were positively correlated. Valsartan decreased the level of AGTR1 in repeatedly OVA-challenged rats. However, AGTR2 mRNA and protein levels in the OVA-challenged rats and high-dose valsartan-treated rats (50 mg x kg(-1) x d(-1)) were also increased. Valsartan significantly decreased inflammatory cell accumulation and attenuated Ach-evoked bronchoconstriction in repeatedly antigen-challenged rats. Valsartan also decreased allergen-induced structural changes in rat airway (including total airway wall thickness and smooth muscle area) and the levels of TGF-beta(1) and PDGF in BALF.

CONCLUSIONSAGTR1 expression is potentially associated with airway remodeling and dysfunction in asthma. Ang II and AGTR1 may participate in airway inflammation and airway remodeling of chronic antigen-exposed rats. Valsartan, a AGTR1 antagonist, could inhibit AGTR1 expression and partially inhibits structural airway changes as well as airway inflammation in chronic OVA-exposed rats.

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Angiotensin Receptor Antagonists ; Animals ; Asthma ; chemically induced ; genetics ; metabolism ; Blotting, Western ; Bronchoalveolar Lavage Fluid ; chemistry ; Enzyme-Linked Immunosorbent Assay ; Gene Expression ; drug effects ; Lung ; drug effects ; metabolism ; pathology ; Male ; Ovalbumin ; Platelet-Derived Growth Factor ; metabolism ; Rats ; Rats, Wistar ; Receptor, Angiotensin, Type 1 ; genetics ; metabolism ; Receptor, Angiotensin, Type 2 ; genetics ; metabolism ; Receptors, Angiotensin ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Tetrazoles ; pharmacology ; Transforming Growth Factor beta1 ; metabolism ; Valine ; analogs & derivatives ; pharmacology ; Valsartan