Angiotensin II Type 1 Receptor Blockers/adverse effects* ; Angiotensin-Converting Enzyme 2 ; Angiotensin-Converting Enzyme Inhibitors/adverse effects* ; Betacoronavirus ; COVID-19 ; Coronavirus Infections/etiology* ; Humans ; Pandemics ; Peptidyl-Dipeptidase A/physiology* ; Pneumonia, Viral/etiology* ; SARS-CoV-2

OBJECTIVETo investigate the effects of angiotensin II type 1 receptor (AT1R) knockdown on the first-phase insulin secretion in isolated islets of db/db mice and explore the possible mechanisms.

METHODSIslets were isolated from db/db and db/m mice and the expression level of AT1R in the islets was assayed. A recombinant adenovirus containing siRNA targeting AT1R (Ad-siAT1R) and a recombinant adenovirus with nonspecific siRNA (Ad-siControl) were constructed to infect the isolated islets for 72 h. AT1R, GLUT-2, and GCK expressions in the islets were investigated and islet perifusion was performed to evaluate the kinetics of insulin release.

RESULTSThe expression level of AT1R in the isolated islets from db/db mice was twice that of islets from db/m mice. The islets treated with Ad-siAT1R showed significantly decreased AT1R mRNA and protein levels and significantly increased expression of GLUT-2 (by 190%) and GCK (by 121%) compared to those treated with Ad-siControl (P<0.05). In response to stimulation with 16.7 mmol/L glucose, the first-phase insulin secretion was impaired in both Ad-siControl group and mock infected group with the peak insulin levels only 1.8 times of the basal level; the first-phase insulin secretion was markedly improved in islets treated with Ad-siAT1R, with a peak insulin level reaching 2.8 times of the basal level.

CONCLUSIONSIn isolated islets of db/db mice, selective AT1R inhibition can restore the first phase insulin secretion by up-regulating GLUT-2 and GCK, which may be one of the potential mechanisms by which AT1R blockers improve insulin secretion function.

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Diabetes Mellitus, Experimental ; Gene Knockdown Techniques ; Glucose ; Glucose Transporter Type 2 ; metabolism ; Insulin ; secretion ; Islets of Langerhans ; metabolism ; Mice ; Protein-Serine-Threonine Kinases ; metabolism ; RNA, Small Interfering ; pharmacology

BACKGROUND: The aim of this study was to examine whether PD 123319 (an angiotensin II type 2 [AT2] receptor antagonist) can influence the release of catecholamines (CA) from the perfused model of the rat adrenal medulla. METHODS: The adrenal gland was isolated by the modification of Wakade method, and perfused with normal Krebs-bicarbonate solution. The content of CA was measured using the fluorospectrophotometer. RESULTS: During perfusion of PD 123319 (range, 5 to 50 nM) into an adrenal vein for 90 minutes the CA secretory responses evoked by acetylcholine (ACh), high K+, 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), and McN-A-343 was dose- and time-dependently inhibited. Furthermore, loading with PD 123319 for 90 minutes also markedly inhibited the CA secretory responses evoked by 4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro-methyl-phenyl)-pyridine-5-carboxylate (Bay-K-8644), cyclopiazonic acid, veratridine, and angiotensin II (Ang II). PD 123319 did not affect basal CA output. Simultaneous perfusion of PD 123319 and CGP 42112 perfused into an adrenal vein for 90 minutes rather more potently inhibited the CA seretory responses evoked by Ach, high K+, DMPP, Bay-K-8644, veratridine, and Ang II compared to the inhibitory effect by PD123319-treated alone. CONCLUSIONS: Taken together, these results show that PD 123319 inhibits the CA secretion evoked by both cholinergic and Ang II receptor stimulation from the perfused rat adrenal medulla. This inhibitory effect of PD 123319 seems to be exerted by blocking the influx of both Na+ and Ca2+ through their voltage-dependent channels into the rat adrenomedullary chromaffin cells as well as by reducing the Ca2+ release from its cytoplasmic calcium store, which may be relevant to AT2 receptor blockade. Based on these present data, it is thought that PD 123319 has different activity from previously known AT2 antagonist activity in the perfused adrenal medulla, and that AT2 receptors may be involved in the rat adrenomedullary CA secretion.
(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride ; 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester ; Acetylcholine ; Adrenal Glands ; Adrenal Medulla ; Angiotensin II ; Angiotensin II Type 2 Receptor Blockers ; Animals ; Calcium ; Catecholamines ; Chromaffin Cells ; Cytoplasm ; Dimethylphenylpiperazinium Iodide ; Imidazoles ; Indoles ; Oligopeptides ; Perfusion ; Pyridines ; Rats ; Veins ; Veratridine

OBJECTIVETo characterize if irbesartan regulates vascular inflammatory gene expression profiles related to atherosclerosis in EA.hy926 cells.

METHODSHuman umbilical vein endothelial cell line EA.hy926 cultured in vitro was incubated with irbesartan (1×10(-6) mol/L) for 24 h. The total RNA was extracted from the cells for gene expression profiling. The DAVID Gene Functional Classification Tool was used to analyze the disease- and function-related genes in the cells. Real-time quantitative polymerase chain reaction (RT-PCR) was used to verify the genes showing differential expression after irbesartan treatment. The protein levels of angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R) were tested by Western blotting.

RESULTSCompared with the control cells, 56 genes were found to show marked changes following irbesartan treatment, including 39 up-regulated and 17 down-regulated genes. Disease analysis suggested that these genes were related to such diseases as coronary atherosclerosis, myocardial infarction, and colorectal cancer. Eight genes, namely MMP2, PTGS2, PECAM1, SELP, SELL, CYP1A1, MMRN1, and HSPA1A, were involved in atherosclerosis and myocardial infarction. Verification by RT-PCR produced a result consistent with the gene array result. AT1R was down-regulated while AT2R up-regulated in irbesartan-treated cells.

CONCLUSIONIrbesartan regulates the inflammatory gene expressions related to atherosclerosis in EA.hy926 cells. These inflammatory factors may promote destabilization of atherosclerotic plaque possibly in relation to AT2R overexpression.

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Atherosclerosis ; genetics ; pathology ; prevention & control ; Biphenyl Compounds ; pharmacology ; Cell Line ; Cytoprotection ; Gene Expression Profiling ; Human Umbilical Vein Endothelial Cells ; drug effects ; pathology ; Humans ; Inflammation ; genetics ; Receptor, Angiotensin, Type 1 ; genetics ; Receptor, Angiotensin, Type 2 ; genetics ; Tetrazoles ; pharmacology

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

BACKGROUNDThe development of diabetic cardiomyopathy is multifactorial. Insulin resistance (IR) and excessive activity of the renin-angiotensin system are confirmed reasons for diabetic cardiomyopathy. Renin-angiotensin system (RAS) inhibitors can reduce tissue Ang II levels, with beneficial effects on cardiovascular function. Therefore, in type-2 diabetes mellitus (T2DM), blockade of the RAS may have the function of protecting against diabetic cardiomyopathy through increasing insulin sensitivity and inhibiting excessive activity of RAS. However, this has not been confirmed.

METHODSThe effect of valsartan, an angiotensin receptor blocker (ARB), on diabetic cardiomyopathy in the presence of T2DM was studied. Wistar rats with T2DM and T2DM treated with valsartan were studied. Glucose infusion rates (GIR), index of IR, heart weight, the heart weight-to-body weight ratio (HW/BW), myocardial apoptotic index, cardiac hydroxyprolin content, and cardiac tissue collagen type I and collagen type III content were measured.

RESULTSGIR in T2DM rats and T2DM rats treated with valsartan decreased (P < 0.01). In T2DM rats treated with valsartan, heart weight, myocardial apoptotic index, cardiac hydroxyprolin content, and cardiac tissue collagen type I and collagen type III content were higher than in control rats, but lower than in T2DM rats. In rats with T2DM, GIR was negatively and significantly correlated with all the variables. However, in T2DM rats treated with valsartan or normal control rats, none of the correlations was significant.

CONCLUSIONSIn the presence of T2DM, diabetic cardiomyopathy is related with IR. Valsartan can not alleviate IR, but can protect against diabetic cardiomyopathy and remove the correlation between IR and diabetic cardiomyopathy.

Angiotensin II Type 1 Receptor Blockers ; therapeutic use ; Animals ; Apoptosis ; Collagen Type I ; analysis ; Collagen Type III ; analysis ; Diabetes Mellitus, Type 2 ; complications ; drug therapy ; metabolism ; Diabetic Cardiomyopathies ; prevention & control ; Hydroxyproline ; analysis ; Insulin Resistance ; Male ; Myocardium ; chemistry ; pathology ; Rats ; Rats, Wistar ; Tetrazoles ; therapeutic use ; Valine ; analogs & derivatives ; therapeutic use ; Valsartan

OBJECTIVETo investigate the effect of angiotensin (Ang)II and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.

METHODSModels of acute ischemic reperfusion injury were established and the level of local AngII, a key element of renin-angiotensin system (RAS), in kidney was measured using radioimmunity technique. The expression of alpha-smooth muscle actin (alpha-SMA), a phenotype of mesenchymal cells, was detected by RT-PCR and immunohistochemistry methods. Renal tubule cells (NRK-52E) were cultured with various concentration of AngII, followed by blocking of PD123319, AngII receptor 2 antagonist, and AG490, an inhibitor of JAK2 signal pathway.

RESULTSAngII of kidney tissue increased immediately after acute ischemic-reperfusion injury, in time dependent fashion. Expression of alpha-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of AngII and was dose and time dependent. The peak of alpha-SMA expression was seen after 30 minute treatment at the dose of 10(-9) mol/L, which was interrupted by both of PD123319 and AG490.

CONCLUSIONSTransdifferentiation of renal tubular epithelial cells occurs under acute ischemic-reperfusion injury. Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.

Actins ; genetics ; metabolism ; Angiotensin II ; administration & dosage ; metabolism ; pharmacology ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Cell Differentiation ; drug effects ; Cell Line ; Dose-Response Relationship, Drug ; Imidazoles ; pharmacology ; Janus Kinase 2 ; antagonists & inhibitors ; Kidney Tubules ; cytology ; metabolism ; Male ; Pyridines ; pharmacology ; RNA, Messenger ; metabolism ; Rats ; Rats, Wistar ; Renin-Angiotensin System ; Reperfusion Injury ; metabolism ; pathology ; Signal Transduction ; drug effects ; Tyrphostins ; pharmacology

OBJECTIVETo investigate the effects of valsartan on expression of angiotensin II receptors in different regions of heart after myocardial infarction (MI).

METHODSCanines were divided into sham-operated control group (n=7), infarction group (n=7) and Valsartan group (10 mg x kg(-1) x day(-1) for 4 weeks after MI operation, n=7). Four weeks after operation, Doppler tissue imaging (DTI) was used to evaluate regional ventricular function in the noninfarcted myocardium (apical and basal near to the infarction region). The mRNA and protein expressions of angiotensin II type 1 receptor (AT1-R) and angiotensin II type 2 receptor (AT2-R) on the corresponding regions were detected by competitive reverse-transcriptase polymerase chain reaction technique and immunohistochemical technique respectively. Results The protein and mRNA expressions of AT1-R were significantly increased in both apical and basal regions near to the infarction in dogs with MI compared with those in control group (P < 0.05) which could be downregulated by valsartan (P < 0.05). AT2-R expressions were significantly upregulated in infarction group in both apical and basal regions compared with those in control group and valsartan further increased AT2-R expressions in both areas (P < 0.05). Myocardial peak systolic velocity (Sm), myocardial peak early diastolic velocity (Em) and myocardial peak late diastolic velocity (Am) at both apical and basal regions near to the infarction regions were significantly lower in MI group than those in the control group which could be significantly improved by valsartan.

CONCLUSIONBoth mRNA and protein expressions of AT1-R and AT2-R are upregulated in noninfarcted regions near MI, valsartan improved myocardial function via inhibiting AT1-R upregulation and enhancing AT2-R upregulation.

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; therapeutic use ; Animals ; Dogs ; Female ; Male ; Myocardial Infarction ; drug therapy ; metabolism ; physiopathology ; Myocardium ; metabolism ; RNA, Messenger ; metabolism ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism ; Tetrazoles ; pharmacology ; therapeutic use ; Valine ; analogs & derivatives ; pharmacology ; therapeutic use ; 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

OBJECTIVETo investigate the effects of angiotensin II (AngII) receptor (AT(1), AT(2)) antagonists on myocardial matrix metalloproteinases (MMPs) and fibronectin (FN) in rats with myocardial infarction (MI).

METHODSRat MI was induced by permanent ligation of the left coronary artery. Placebo, AT(1) receptor antagonist valsartan (10 mgxkg(-1)xd(-1)) or AT(2) receptor antagonist PD123319 (30 mgxkg(-1)xd(-1)) were given 7 days prior MI surgery. On the 1st, 3rd and 7th day after MI, Expressions of MMP-2, 3, 9, tissue inhibitors of matrix metalloproteinase-1 (TIMP-1) and FN at protein level were determined by Western blot in left ventricular free wall (LVFW), interventricular septum (IS) and right ventricular (RV). Myocardial FN distribution was also assayed by immunofluorescence.

RESULTSTypical myocardial remodeling was shown in IS and LVFW 7 days after MI. MMP-2, 3, 9 expressions at protein level were significantly increased whereas TIMP-1 and FN expressions significantly decreased in IS 1, 3, 7 days post MI in a time-dependent manner compared to that of sham operated hearts. MMP-2, 3, 9 expressions was significantly increased and TIMP-1 and FN expression significantly decreased in LVFW at the 1st post MI day and maintained up to 7th post MI day compared to that of sham operated hearts. Up-regulated expressions of MMP-2, 3, 9 and down-regulated TIMP-1 and FN expressions in IS and LVFW could be significantly attenuated by valsartan but not by PD123319. Valsartan but not PD123319 also significantly reduced MI sizes (40.4% +/- 2.1% vs 49.5% +/- 2.1%, P < 0.05).

CONCLUSIONAT(1) receptor antagonist involves in the pathology procession of myocardial remodeling and might lead to the development and progression of congestive heart failure by the increasing expressions of MMP-2, 3, 9, which contribute to degradative extracellular matrix FN in myocardium.

Angiotensin II Type 1 Receptor Blockers ; therapeutic use ; Animals ; Fibronectins ; biosynthesis ; Male ; Matrix Metalloproteinase 2 ; biosynthesis ; Matrix Metalloproteinase 3 ; biosynthesis ; Matrix Metalloproteinase 9 ; biosynthesis ; Myocardial Infarction ; drug therapy ; pathology ; Rats ; Rats, Wistar