Objective: To investigate the effect and mechanism of sacubitril/valsartan on left ventricular remodeling and cardiac function in rats with heart failure. Methods: A total of 46 SPF-grade male Wistar rats weighed 300-350 g were acclimatized to the laboratory for 7 days. Rats were then divided into 4 groups: the heart failure group (n=12, intraperitoneal injection of adriamycin hydrochloride 2.5 mg/kg once a week for 6 consecutive weeks, establishing a model of heart failure); heart failure+sacubitril/valsartan group (treatment group, n=12, intragastric administration with sacubitril/valsartan 1 week before the first injection of adriamycin, at a dose of 60 mg·kg^-1·d^-1 for 7 weeks); heart failure+sacubitril/valsartan+APJ antagonist F13A group (F13A group, n=12, adriamycin and sacubitril/valsartan, intraperitoneal injection of 100 μg·kg^-1·d^-1 APJ antagonist F13A for 7 weeks) and control group (n=10, intraperitoneal injection of equal volume of normal saline). One week after the last injection of adriamycin or saline, transthoracic echocardiography was performed to detect the cardiac structure and function, and then the rats were executed, blood and left ventricular specimens were obtained for further analysis. Hematoxylin-eosin staining and Masson trichrome staining were performed to analyze the left ventricular pathological change and myocardial fibrosis. TUNEL staining was performed to detect cardiomyocyte apoptosis. mRNA expression of left ventricular myocardial apelin and APJ was detected by RT-qRCR. ELISA was performed to detect plasma apelin-12 concentration. The protein expression of left ventricular myocardial apelin and APJ was detected by Western blot. Results: Seven rats survived in the heart failure group, 10 in the treatment group, and 8 in the F13A group. Echocardiography showed that the left ventricular end-diastolic diameter (LVEDD) and the left ventricular end-systolic diameter (LVESD) were higher (both P<0.05), while the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were lower in the heart failure group than in the control group (both P<0.05). Compared with the heart failure group, rats in the treatment group were featured with lower LVEDD and LVESD (both P<0.05), higher LVEF and LVFS (both P<0.05), these beneficial effects were reversed in rats assigned to F13A group (all P<0.05 vs. treatment group). The results of HE staining showed that the cardiomyocytes of rats in the control group were arranged neatly and densely structured, the cardiomyocytes in the heart failure group were arranged in disorder, distorted and the gap between cells was increased, the cardiomyocytes in the treatment group were slightly neat and dense, and cardiomyocytes in the F13A group were featured similarly as the heart failure group. Masson staining showed that there were small amount of collagen fibers in the left ventricular myocardial interstitium of the control group, while left ventricular myocardial fibrosis was significantly increased, and collagen volume fraction (CVF) was significantly higher in the heart failure group than that of the control group (P<0.05). Compared with the heart failure group, the left ventricular myocardial fibrosis and the CVF were reduced in the treatment group (both P<0.05), these effects were reversed in the F13A group (all P<0.05 vs. treatment group). TUNEL staining showed that the apoptosis index (AI) of cardiomyocytes in rats was higher in the heart failure group compared with the control group (P<0.05), which was reduced in the treatment group (P<0.05 vs. heart failure group), this effect again was reversed in the F13A group (P<0.05 vs. treatment group). The results of RT-qPCR and Western blot showed that the mRNA and protein levels of apelin and APJ in left ventricular myocardial tissue of rats were downregulated in heart failure group (all P<0.05) compared with the control group. Compared with the heart failure group, the mRNA and protein levels of apelin and APJ were upregulated in the treatment group (all P<0.05), these effects were reversed in the F13A group (all P<0.05 vs. treatment group). ELISA test showed that the plasma apelin concentration of rats was lower in the heart failure group compared with the control group (P<0.05); compared with the heart failure group, the plasma apelin concentration of rats was higher in the treatment group (P<0.05), this effect was reversed in the F13A group (P<0.05 vs. treatment group). Conclusion: Sacubitril/valsartan can partially reverse left ventricular remodeling and improve cardiac function in rats with heart failure through modulating Apelin/APJ pathways.
Aminobutyrates/pharmacology* ; Animals ; Apelin/metabolism* ; Biphenyl Compounds ; Collagen/metabolism* ; Doxorubicin/pharmacology* ; Fibrosis ; Heart Failure/pathology* ; Male ; Myocytes, Cardiac/pathology* ; RNA, Messenger/metabolism* ; Rats ; Rats, Wistar ; Valsartan/pharmacology* ; Ventricular Function, Left/drug effects* ; Ventricular Remodeling

OBJECTIVE: To investigate the effect of honokiol (HKL) for reducing doxorubicin (DOX)-induced cardiotoxicity in H9c2 cells and the underlying mechanisms. METHODS: H9c2 cells were divided into control group, DOX group, HKL + DOX group, and HKL+compound C+DOX group. After 24 h of corresponding treatment, the cells were examined for morphological changes and cell viability using CCK-8 assay. The mRNA expressions of the inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were detected by RT-PCR, and the protein levels of cleaved caspase-3, cytochrome c, NOD-like receptor pyrin domain containing 3 (NLRP3), caspase-1, apoptosis-associated speck-like protein containing a CARD (ASC), p-AMPK and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) were detected with Western blotting; the expressions of NLRP3 and p-AMPK also detected with immunofluorescence staining. RESULTS: DOX treatment caused swelling and significantly lowered the viability of H9c2 cells (P < 0.05), resulting also in increased mRNA expressions of TNF-α, IL-6 and IL-1β (P < 0.05) and protein expressions of cleaved caspase-3, cytochrome c, NLRP3, caspase-1 and ASC (P < 0.05) but reduced protein levels of p-AMPK and Nrf2 (P < 0.05); fluorescence staining showed significantly increased NLRP3 expression and decreased expression of p-AMPK in DOX-treated cells (P < 0.05). All these changes in COX-treated cells were significantly alleviated by HKL treatment (P < 0.05). The application of compound C obviously mitigated the protective effects of HKL against DOX-induced cardiotoxicity in H9c2 cells. CONCLUSIONS HKL can alleviate DOX-induced cardiotoxicity by inhibiting pyroptosis in H9c2 cells, and this effect is mediated by activation of AMPK to regulate Nrf2 signaling.
AMP-Activated Protein Kinases/metabolism* ; Allyl Compounds ; Biphenyl Compounds ; Cardiotoxicity/pathology* ; Caspase 3/metabolism* ; Cytochromes c ; Doxorubicin/adverse effects* ; Humans ; Interleukin-6/metabolism* ; Myocytes, Cardiac ; NF-E2-Related Factor 2/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Phenols ; Pyroptosis ; RNA, Messenger/metabolism* ; Tumor Necrosis Factor-alpha/metabolism*

OBJECTIVEMyanmar has a long history of using medicinal plants for treatment of various diseases. To the best of our knowledge there are no previous reports on antiglycation activities of medicinal plants from Myanmar. Therefore, this study was aimed to evaluate the antioxidant, antiglycation and antimicrobial properties of 20 ethanolic extracts from 17 medicinal plants indigenous to Myanmar.

METHODSIn vitro scavenging assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), superoxide (SO) radicals were used to determine the antioxidant activities. Folin-Ciocalteu's method was performed to determine the total phenolic content. Antiglycation and antimicrobial activities were detected by bovine serum albumin-fluorescent assay and agar well diffusion method.

RESULTSTerminalia chebula Retz. (Fruit), containing the highest total phenolic content, showed high antioxidant activities with inhibition of 77.98% ± 0.92%, 88.95% ± 2.42%, 88.56% ± 1.87% and 70.74%± 2.57% for DPPH, NO, SO assays and antiglycation activity respectively. It also showed the antimicrobial activities against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans with inhibition zone of 19, 18, 17, 25 and 15 mm, respectively. Garcinia mangostana Linn. showed the strongest activities for SO and antiglycation assays with inhibition of 93.68% ± 2.63% and 82.37% ± 1.78%. Bark of Melia sp. was the best NO radical scavenger with inhibition rate of 89.39%± 0.60%.

CONCLUSIONThe results suggest that these plants are potential sources of antioxidants with free radical-scavenging and antiglycation activities and could be useful for decreasing the oxidative stress and glycation end-product formation in glycation-related diseases.

Anti-Bacterial Agents ; analysis ; pharmacology ; Anti-Infective Agents ; analysis ; pharmacology ; Antioxidants ; analysis ; pharmacology ; Bacteria ; drug effects ; growth & development ; Biphenyl Compounds ; metabolism ; Candida albicans ; drug effects ; growth & development ; Fruit ; Garcinia ; chemistry ; Glycation End Products, Advanced ; metabolism ; Humans ; Magnoliopsida ; chemistry ; Medicine, Traditional ; Melia ; chemistry ; Myanmar ; Nitric Oxide ; metabolism ; Oxidative Stress ; drug effects ; Phenols ; analysis ; pharmacology ; Phytotherapy ; Picrates ; metabolism ; Plant Bark ; Plant Extracts ; chemistry ; pharmacology ; Plants, Medicinal ; Superoxides ; Terminalia ; chemistry

To explore the effects of honokiol (HKL) on pulmonary microvascular endothelial cells in lipopolysaccharide (LPS)-induced acute respiratory distress syndrome (ARDS) and the underlying mechanisms.
 Methods: In animal experiment, a total of 40 C57BL/6J mice were randomly divided into a control group (Con group), a LPS intervention group (LPS group), a LPS+honokiol (HKL) intervention group (HKL group) and a LPS+HKL+nicotinamide (NAM) intervention group (NAM group) (n=10 in each group). In the cell experiment, the experiment cells were divided into a control group (Con group), a LPS intervention group (LPS group), a LPS+HKL intervention group (HKL group), a LPS+HKL+NAM intervention group (NAM group), and a LPS+HKL+compound C (CMC) intervention group (CMC group). The pathological changes of the lung tissues were evaluated by hematoxylin and eosin (HE) staining; the protein concentration, total cells and neutrophils in the bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in the lung tissues were detected; the changes of pulmonary microvascular permeability were determined by Evans blue assay; the effect of HKL on the vitality of human pulmonary microvascular endothelial cells were examined by cell counting kit-8 (CCK-8); the inhibitors including NAM and CMC were applied to explore the molecular mechanism of the protective effects of HKL. The expression levels of Sirt3, caspase-3, cleaved caspase-3, Bcl-2, Bax, p-adenosine monophosphate activated protein kinase (p-AMPK) and AMPK in lung tissues or cells were detected by Western blot.
 Results: In animal models, compared with the Con group, the mice in the LPS group displayed typical ARDS pathological changes, and the ratio of lung wet/dry weight (W/D) and MPO activity in the lung tissues, protein concentration, total cells and neutrophils in BALF, Evans blue leaking index (ELI), expression levels of cleaved caspase-3 were significantly increased (all P<0.05), while the expression levels of Sirt3 was obviously decreased (P<0.05). Compared with the LPS group, the above changes in the LPS group were significantly improved in the HKL group (all P<0.05); Compared with the HKL group, the curative effect of HKL intervention could be partly inhibited in the NAM group (P<0.05). In cell experiments, compared with the LPS group, the HPMECs viability in the HKL group was markedly improved (P<0.05), while the expression levels of Bcl-2 and Sirt3 were significantly upregulated (P<0.05), and the expression levels of Bax and cleaved caspase-3 were significantly downregulated (P<0.05), accompanied by the activation of AMPK pathway (P<0.05) in the HKL group. Compared with the HKL group, the curative effect of HKL intervention was partly inhibited in the CMC group (P<0.05).
 Conclusion: HKL can significantly attenuate LPS-induced lung injury and inhibit the apoptosis of pulmonary microvascular endothelial cells through regulation of Sirt3/AMPK pathway.
AMP-Activated Protein Kinases ; metabolism ; Acute Lung Injury ; chemically induced ; drug therapy ; Animals ; Biphenyl Compounds ; pharmacology ; therapeutic use ; Humans ; Lignans ; pharmacology ; therapeutic use ; Lipopolysaccharides ; Lung ; Mice ; Mice, Inbred C57BL ; Mitochondria ; drug effects ; metabolism ; Signal Transduction ; drug effects ; Sirtuin 3 ; metabolism

To explore the therapeutic effect of honokiol on particulate matter 2.5 (PM2.5)-induced lung injury in asthmatic mice and the possible mechanisms.
 Methods: A total of 32 BALB/C mice were randomly divided into four groups: a normal saline group, a model group, a PM2.5 group and a honokiol group (n=8 in each group). The asthma mouse model was established by ovalbumin treatment. The mice were treated with physiological saline, ovalbumin, PM2.5 and honokiol, respectively. Lung tissues and serum were collected. The pathological changes of lung tissues were evaluated. The levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and serum were measured and the expressions of Toll like receptor 4 (TLR4), nuclear factor kappa B (NF-κB), retinoid-related orphan receptor gamma-t (RORγt) and forkhead box protein 3 (Foxp3) in lung tissues were detected.
 Results: 1) The lung tissues of mice in the asthma group showed obvious pathological changes and inflammatory state, suggesting that the asthma model was established successfully. PM2.5 could aggravate the pathological condition of inflammatory injury in lung tissues in asthmatic mice. 2) Compared to the PM2.5 group, the pathological symptoms in the lung tissues were alleviated in the honokiol group and the percentage of inflammatory cells in BALF and the levels of inflammatory cytokines in BALF and serum were significantly reduced (all P<0.05). 3) Compared to the PM2.5 group, the expressions of TLR4, NF-κB (p-p65) and RORγt in lung tissues were significantly decreased, while the expression of Foxp3 was increased; the ratio of RORγt/Foxp3 was also decreased in the honokiol group (all P<0.05).
 Conclusion: Honokiol can resist lung injury induced by PM2.5 in asthmatic mice. These effects are through inhibiting TLR4-NF-κB pathway-mediated inflammatory response or regulating the balance of Th17/Treg cells.
Animals ; Asthma ; chemically induced ; complications ; Biphenyl Compounds ; pharmacology ; Bronchoalveolar Lavage Fluid ; chemistry ; Cytokines ; analysis ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Inflammation Mediators ; analysis ; Lignans ; pharmacology ; Lung ; metabolism ; pathology ; Lung Injury ; drug therapy ; etiology ; metabolism ; pathology ; Mice ; Mice, Inbred BALB C ; NF-kappa B ; metabolism ; Ovalbumin ; Particulate Matter ; toxicity ; Random Allocation ; Toll-Like Receptor 4 ; metabolism

In the present study, three new triterpenoids, 23-hydroxyurs-12, 18-dien-28-oic acid 3β-O-α-L-arabinopyranoside (1), 23-hydroxyurs-12, 18-dien-28-oic acid 3β-O-β-D-glucuronopyranoside-6-O-methyl ester (2), and urs-12, 18-dien-28-oic acid 3β-O-β-D-glucuronopyranoside-6-O-methyl ester (3), and a known triterpenoid, 3β-hydroxy-urs-2, 18-dien-28-oic acid (4, randialic acid B), were isolated from the aerial parts of Ilex cornuta. Their structures were identified by the spectroscopic analyses (IR, ESI-MS, HR-ESI-MS, and 1D and 2D NMR) and chemical reactions. Compound 4 showed significant cell-protective effects against HO-induced H9c2 cardiomyocyte injury. Compounds 1-4 did not show any significant DPPH radical scavenging activity.
Animals ; Biphenyl Compounds ; metabolism ; Cardiovascular Agents ; chemistry ; isolation & purification ; pharmacology ; Hydrogen Peroxide ; metabolism ; Ilex ; chemistry ; Molecular Structure ; Myocardium ; cytology ; pathology ; Myocytes, Cardiac ; drug effects ; Picrates ; metabolism ; Plant Components, Aerial ; chemistry ; Plant Extracts ; chemistry ; pharmacology ; Rats ; Triterpenes ; chemistry ; isolation & purification ; pharmacology

OBJECTIVETo investigate the effect of magnolol on proliferation and apoptosis of HL-60 cells and its mechanism.

METHODSMTT assay was used to measure the proliferation of HL-60 cells after treatment with different concentration of magnolol (5, 10, 20, 40, 80 and 160 µg/ml). The morphological changes of HL-60 cells were examined by light microscopy, and DAPI staining was performed to observe the nuclear morphology of HL-60 cells. The early cell apoptosis was detected by flow cytometry with Annexin V-FITC/PI double-staining. RT-PCR was carried out to examine the mRNA expression of BAX and BCL-2. Western blot was performed to detect the protein expression of caspase family.

RESULTSThe magnolol inhibited HL-60 cell proliferation, and the inhibitory rate of cell proliferation increased significantly in a dose- and time- dependent manner (P < 0.05). HL-60 cells became small, even apoptotic bodies appeared after treatment with magnolol. In addition, nuclear condensation or fragmentation could be observed, which is the typical morphological features of apoptosis. When HL-60 cells were treated with 40 µg/ml of magnolol for 24 h, the ratio of early apoptotic cells reached to (11.7 ± 2.4) %, which was significant different from control (1.4 ± 1.1) % (P < 0.05). RT-PCR results showed that treatment of HL-60 cells with magnolol up-regulated the expression of BAX, whereas down-regulated the expression of BCL-2. Western blot results showed that the cleavages of caspase-3, -8 and -9 were significantly enhanced by magnolol.

CONCLUSIONThe magnolol can significantly inhibit the proliferation of HL-60 cells and induce the apoptosis of HL-60 cells, which may occur through up-regulation of BAX, down-regulation of BCL-2 and the activation of caspases.

Apoptosis ; drug effects ; Biphenyl Compounds ; pharmacology ; Caspases ; metabolism ; Cell Proliferation ; drug effects ; Down-Regulation ; Flow Cytometry ; HL-60 Cells ; drug effects ; Humans ; Lignans ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Up-Regulation ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo investigate the protective effects of irbesartan against cardiac inflammation associated with diabetes and obesity in the db/db mouse model of type 2 diabetes and explore the underlying mechanisms.

METHODSTwenty- four 10-week-old diabetic db/db mice were equally randomized into irbesartan treatment (50 mg/kg per day) group and model group, using 12 nondiabetic littermates (db/+) as the controls, The mice were treated with irbesartan or saline vehicle for 16 consecutive weeks, after which the heart pathology was observed and the heart weight, body weight, and serum levels of fasting blood glucose (FBG), total cholesterol(TC), and triglycerides(TG) were measured. The expression of nuclear factor-kappaB (NF-κB) p65 in the myocardium was assessed with immunohistochemistry, the protein levels of P-IκBα ,IκBα and β-actin were analyzed with Western blotting, and the pro-inflammatory cytokines IL-6 and TNF-α mRNA were detected using quantitative real-time PCR (qPCR).

RESULTSCompared with db/+ mice, the saline-treated db/db mice developed obesity, hyperglycemia and hyperlipidemia (P<0.01). Histopathological examination of the heart tissue revealed inflammatory cell infiltration, increased myocardial interstitium and disorders of myocardial fiber arrangement. The diabetic mice showed increased P-IαBα and decreased IκBα protein levels, enhanced activity and expression of NF-κB in the hearts, and increased mRNA expression of IL-6 and TNF-α in the myocardium. These abnormalities were all associated with increased inflammatory response. Treatment with irbesartan improved the heart architecture and attenuated high glucose-induced inflammation in the diabetic mice.

CONCLUSIONTreatment with irbesartan attenuates cardiac inflammation in type 2 diabetic db/db mice, and this effect was probably associated with the suppression of cardiac angiotensin II and NF-κB signaling pathway.

Actins ; metabolism ; Angiotensin II ; metabolism ; Animals ; Biphenyl Compounds ; pharmacology ; Cardiovascular Diseases ; drug therapy ; Diabetes Mellitus, Experimental ; complications ; Diabetes Mellitus, Type 2 ; complications ; Inflammation ; drug therapy ; Interleukin-6 ; metabolism ; Mice ; Obesity ; complications ; Random Allocation ; Real-Time Polymerase Chain Reaction ; Signal Transduction ; Tetrazoles ; pharmacology ; Transcription Factor RelA ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo observe the effect of Tripterygium glycosides (TG) on the expression of hypoxia-inducible factor-1α and endothelin-1 in the kidney of diabetic rats and explore the possible mechanism underlying the protective effect of TG against diabetic nephropathy.

METHODSSixty 8-week-old male SD rats were randomly divided into normal control group (n=10) and streptozotocin-induced diabetes mellitus (DM) model group (n=50). The diabetic model rats were then randomly divided into DM group, low-dose (8 mg/kg) and high-dose (16 mg/kg) TG treatment groups, and Irbesartan (50 mg/kg) treatment group. After 8 weeks, the levels of blood glucose (BG), 24-h urine protein (24 h Upro), serum creatinine (Scr) and blood urea nitrogen (BUN) were measured. The pathological changes in the renal tissues were examined by optical microscopy, and the mean glomerular area (MGA) and mean glomerular volume (MGV) were measured with pathological image analysis. Immunohistochemical and Western blotting were used to detect the expression of HIF-1α and ET-1 protein in the renal tissue, and their mRNA expressions were detected using real-time fluorescence quantitative PCR.

RESULTSHIF-1α and ET-1 expression increased in the kidney of diabetic rats. Compared with the diabetic model rats, the rats receiving TG and Irbesartan treatment showed decreased levels of Scr, BUN, 24h Upro, MGA and MGV, improved renal histopathology, and reduced expression of HIF-1α and ET-1 mRNA and protein in the renal tissue. These changes were more obvious in high-dose TG treatment group. Correlation analysis showed that the expression of HIF-1α was positively correlated with that of ET-1, and they were both positively correlated with kidney weight index (KW/BW), 24 h Upro, MGA, and MGV.

CONCLUSIONHIF-1α and ET-1 are overexpressed in the kidney of diabetic rats. TG can improve kidney damage in diabetic rats and delay the development of diabetic nephropathy by inhibiting the HIF-1α and ET-1 expression.

Animals ; Biphenyl Compounds ; pharmacology ; Blood Glucose ; Blood Urea Nitrogen ; Creatinine ; blood ; Diabetes Mellitus, Experimental ; metabolism ; Endothelin-1 ; metabolism ; Glycosides ; pharmacology ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Kidney ; drug effects ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Tetrazoles ; pharmacology ; Tripterygium ; chemistry

Angiotensin receptor blockers (ARBs) have organ-protective effects in heart failure and may be also effective in doxorubicin-induced cardiomyopathy (DOX-CMP); however, the efficacy of ARBs on the prevention of DOX-CMP have not been investigated. We performed a preclinical experiment to evaluate the preventive effect of a novel ARB, fimasartan, in DOX-CMP. All animals underwent echocardiography and were randomly assigned into three groups: treated daily with vehicle (DOX-only group, n=22), 5 mg/kg of fimasartan (Low-fima group, n=22), and 10 mg/kg of fimasartan (High-fima group, n=19). DOX was injected once a week for six weeks. Echocardiography and hemodynamic assessment was performed at the 8th week using a miniaturized conductance catheter. Survival rate of the High-fima group was greater (100%) than that of the Low-fima (75%) and DOX-only groups (50%). Echocardiography showed preserved left ventricular (LV) ejection fraction in the High-fima group, but not in the DOX-only group (P=0.002). LV dimensions increased in the DOX-only group; however, remodeling was attenuated in the Low-fima and High-fima groups. Hemodynamic assessment showed higher dP/dt in the High-fima group compared with the DOX-only group. A novel ARB, fimasartan, may prevent DOX-CMP and improve survival rate in a dose-dependent manner in a rat model of DOX-CMP and could be a treatment option for the prevention of DOX-CMP.
Angiotensin Receptor Antagonists/*therapeutic use ; Animals ; Biphenyl Compounds/*therapeutic use ; Cardiomyopathies/chemically induced/mortality/*prevention & control ; Doxorubicin/*toxicity ; Echocardiography ; Hemodynamics ; Pyrimidines/*therapeutic use ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1/chemistry/*metabolism ; Survival Rate ; Tetrazoles/*therapeutic use ; Ventricular Function, Left/physiology