NAD(P)H oxidase plays an important role in hypertension and its complication in aldosterone-salt rat. We questioned whether NAD(P)H oxidase subunit expression and activity are modulated by aldosterone and whether this is associated with target- organ damage. Rats were infused with aldosterone (0.75 microgram/hr/day) for 6 weeks and were given 0.9% NaCl+/-losartan (30 mg/kg/day), spironolactone (200 mg/kg/ day), and apocynin (1.5 mM/L). Aldosterone-salt hypertension was prevented completely by spironolactone and modestly by losartan and apocynin. Aldosterone increased aortic NAD(P)H oxidase activity by 34% and spironolactone and losartan inhibited the activity. Aortic expression of the subunits p47(phox), gp91(phox), and p22(phox) increased in aldosterone-infused rats by 5.5, 4.7, and 3.2-fold, respectively, which was decreased completely by spironolactone and partially by losartan and apocynin. Therefore, the increased expression of NAD(P)H oxidase may contribute to cardiovascular damage in aldosterone-salt hypertension through the increased expression of each subunit.
Acetophenones/administration & dosage ; Aldosterone/administration & dosage/*toxicity ; Aldosterone Antagonists/administration & dosage ; Angiotensin II Type 1 Receptor Blockers/administration & dosage ; Animals ; Anti-Inflammatory Agents, Non-Steroidal/administration & dosage ; Aorta/metabolism/pathology ; Blood Pressure/drug effects ; Hypertension/chemically induced/drug therapy/*enzymology ; Kidney/metabolism/pathology ; Losartan/administration & dosage ; Male ; NADPH Oxidase/antagonists & inhibitors/*metabolism ; Organ Size ; Oxidative Stress ; Protein Subunits/metabolism ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium Chloride/administration & dosage ; Spironolactone/administration & dosage ; Superoxides/metabolism

OBJECTIVETo evaluate the efficacy and safety of olmesartan medoxomil compared with losartan potassium in patients with mild to moderate essential hypertension.

METHODThis is a randomized, double-blind, double-dummy, active-controlled, parallel, multi-center study. After a 2-week placebo run-in period, a total of 287 eligible subjects were randomized at 1:1 ratio to receive olmesartan medoxomil 20 mg or losartan potassium 50 mg, once daily for 8 weeks. The blood pressure was assessed after 4 weeks treatment. If the subject's seating diastolic blood pressure (SeDBP) was still >or=90 mm Hg, the dosage was doubled for another 4 weeks; for those subjects whose SeDBP was <90 mm Hg after 4-week treatment, the initial dosage remained unchanged and the treatment continued until completion of the study.

RESULTS(1) The mean trough reduction in SeDBP from baseline in olmesartan group was significantly greater than that in losartan group after 4 weeks (11.72 mm Hg vs 9.23 mm Hg, P=0.004) and 8 weeks treatment (12.94 mm Hg vs 11.01 mm Hg, P=0.035). (2) The number and percentage of responders in olmesartan group (81, 65.3%) were statistically higher than those (68, 52.7%) in losartan group (P=0.028) after 4 weeks treatment and were similar between the two groups after 8 weeks treatment (P>0.05). (3) Individual and overall trough/peak ratios of DBP and SBP in 24-hour ambulatory blood pressure monitoring were higher in olmesartan group than losartan group. The hypotensive effect of olmesartan was more durable than losartan at 24 hour interval. (4) The incidence of study drug-related adverse events (AEs) in olmesartan group (10.5%) was similar as that in losartan group (13.9%, P>0.05). Most of these AEs were mild and transient.

CONCLUSIONThis study shows that olmesartan medoxomil, at oral dose of 20 mg-40 mg once daily was effective and safe for hypertension treatment and the hypotensive effect was superior to losartan potassium (50 mg-100 mg once daily).

Adolescent ; Adult ; Aged ; Antihypertensive Agents ; administration & dosage ; China ; Double-Blind Method ; Female ; Humans ; Hypertension ; drug therapy ; physiopathology ; Imidazoles ; adverse effects ; therapeutic use ; Losartan ; adverse effects ; therapeutic use ; Male ; Middle Aged ; Olmesartan Medoxomil ; Tetrazoles ; adverse effects ; therapeutic use

To investigate whether brain AT1 receptor stimulation contributes as a hypertensive mechanism to deoxycorticosterone acetate (DOCA)-salt hypertension, losartan (1 mg/4l) or artificial cerebrospinal fluid (aCSF) was injected into the lateral cerebral ventricle in conscious control uninephrectomized Wistar rats or rats with DOCA-salt for 2 or 4 weeks, and mean arterial pressure (MAP) and heart rates (HR) were recorded. In rats with DOCA-salt treatment, resting MAP increased to 144 +/- 6 mmHg after 2 weeks and to 170 +/- 5 mmHg after 4 weeks versus 115- 120 mmHg in controls. In rats with 2 week DOCA-salt treatment, MAP started declining at 4 hr after intracerebroventricular (icv) injection of losartan, and significant decreases in MAP were found at 18 and 24 hr. In rats with 4 week DOCA-salt treatment, MAP was significantly decreased at 4, 18 and 24 hr. In both groups MAP decreased to that of control rats. In control rats, icv losartan had no effect on MAP and HR. Icv aCSF did not significantly change MAP and HR in either DOCA-salt hypertensive rats or control rats. Normalization of MAP after icv administration of the AT1 receptor antagonist suggests a significant role for brain AT1 receptor stimulation in the development and maintenance of hypertension in the DOCA-salt hypertensive rat model.
Animal ; Antihypertensive Agents/*therapeutic use ; Blood Pressure/drug effects ; Desoxycorticosterone ; Heart Rate/drug effects ; Hypertension/*drug therapy/physiopathology ; Injections, Intraventricular ; Losartan/administration & dosage/*therapeutic use ; Male ; Rats ; Rats, Wistar ; Renin-Angiotensin System/physiology ; Sodium Chloride

OBJECTIVETo investigate the effect of AT₁ receptor on the changes of tyrosine hydroxylase-immunoreactivity (TH-IR) in rostral ventrolateral medulla (RVLM) induced by brain cholinergic stimuli in rats.

METHODSMale SD rats were randomly divided into 4 groups: NS + CBC group, Los + CBC group, Los + NS group and NS + NS group. AT₁ was blocked by pretreatment of 20 μg losartan in Los + CBC and Los + NS groups; intracerebroventricular injection of 0.5 μg carbachol was used for cholinergic stimuli in NS + CBC and Los + CBC groups; normal saline (NS) was used for control. The output amount of natrium in kidney, glomerular filtration rate (GFR) and renal plasma flow (PRF) were observed. The changes of TH-IR in the RVLM were observed by immunohistochemistry.

RESULTIn NS + CBC group carbachol induced potent natriuresis, after pretreatment of losartan the natriuretic effect was partially inhibited in Los + CBC group. Both the number and optical density of TH-IR positive neurons in NS + CBC group were markedly increased than those in NS + NS group (P < 0.05); while those in Los + CBC group were significantly lower than those in NS+CBC group (P < 0.05). Intracerebroventricular injection of carbachol and losartan had no effect on GFR and RPF(P > 0.05).

CONCLUSIONThe results suggest that cholinergic stimuli can induce potent natriuresis and increase the activity of adrenergic neurons in the RVLM; the above effects can be down regulated by blockade of brain AT₁ receptor.

Animals ; Carbachol ; administration & dosage ; pharmacology ; Drug Antagonism ; Glomerular Filtration Rate ; drug effects ; Losartan ; pharmacology ; Male ; Medulla Oblongata ; drug effects ; metabolism ; Natriuresis ; drug effects ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; physiology ; Tyrosine 3-Monooxygenase ; metabolism

BACKGROUNDS AND AIMS: Angiotensin receptors are found on hepatic stellate cells, which participate in hepatic fibrosis. Therefore, it is presumed that angiotensin has a role in hepatic fibrosis. The aim of this study was to evaluate the effects of angiotensin blockade on inhibition of hepatic fibrosis in cirrhotic rat model. Material and METHODS: Cirrhosis with portal hypertension was produced by common bile duct ligation (BDL) in the adult Sprague-Dawley rats. They were classified into 4 groups (each group n=6) as follows; G1: BDL without drug, G2: BDL+captopril 100 mg/kg/day beginning 2 weeks after BDL, G3: BDL+captopril 100 mg/kg/day, starting just after BDL, G4: BDL+losartan 10 mg/kg/day, starting just after BDL. After 4 weeks following BDL, hepatic fibrosis was histomorphologically analyzed by Batts & Ludwig score. Alpha smooth muscle actin by immunohistochemical stain, hydroxyproline contents of liver tissue by spectrophotometry and expression of collagen, procollagen, and TGF-beta by real-time PCR were measured. RESULTS: Batts & Ludwig score were 3.8, 3.0, 2.6,and 2.6 in G1, G2, G3, and G4, respectively. The expression of alpha-SMA was significantly lower in G3 and G4 than in G1; 11.9%, 10.9%, 2.6%, and 1.1% in G1, G2, G3, and G4, respectively (p<0.05). The concentration of hydroxyproline (microgram/g liver tissue) was lower in G3 and G4 compared with G1 (p<0.05). Also, the administration of angiotensin blockade just after BDL significantly reduced the expression of collagen, procollagen, and TGF-beta mRNA. CONCLUSIONS: Angiotensin blockades are effective in the prevention of hepatic fibrosis in BDL rats.
Actins/metabolism ; Angiotensin II Type 1 Receptor Blockers/administration & dosage/*therapeutic use ; Animals ; Bile Ducts/pathology/surgery ; Captopril/administration & dosage/*therapeutic use ; Fibrosis ; Hydroxyproline/metabolism ; Ligation ; Liver/drug effects/metabolism/pathology ; Liver Cirrhosis, Experimental/*drug therapy/etiology/metabolism ; Losartan/administration & dosage/*therapeutic use ; Male ; Rats ; Rats, Sprague-Dawley ; Transforming Growth Factor beta/metabolism

In order to investigate whether Yinchenhao decoction (YCHD) attenuates hepatic fibrogenesis in the bile duct ligation (BDL) model via recovering and restoring the self-regulation and balance of the renin-angiotensin system (RAS), 33 specific-pathogen-free (SPF) male Sprague-Dawley rats with common BDL and scission were randomly divided into five groups as follows: G1, the sham group (n=4); G2, BDL 7-day group (n=5); G3, BDL+YCHD 430 mg/mL (n=8); G4, BDL+losartan 0.65 mg/mL (ARB group, n=8); G5, model group (BDL without any treatment, n=8). YCHD and losartan (10 mL·kg(-1)·day(-1)) were given by gastric gavage for 16 days following BDL in G3 and G4 groups, respectively. The effect of YCHD on liver fibrosis and the detailed molecular mechanisms were assessed by liver function including total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IDBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Histological changes were observed by transmission electron microscopy (TEM) and Masson trichrome staining. Western blotting was used to detect the protein expression level of the renin-angiotensin system (RAS) components including angiotensin converting enzyme (ACE), angiotensin II type 1 receptor (AT1R), ACE2, angiotensin II (AngII) as well as transforming growth factor β1 (TGFβ1). The experimental data were analyzed by principle component analytical method of pattern recognition. The results showed that biochemically, serum TBIL, DBIL, IDBIL, ALT and AST levels were markedly increased following BDL as compared with the sham group (P<0.05). Serum TBIL, IDBIL and DBIL levels in G3 group were dramatically decreased as compared with G5 and G4 groups (P<0.05). Serum AST level in G3 was significantly lowered than in G5 group (P<0.05), but there was no significant difference in ALT among G3, G4 and G5 groups (P>0.05). Histologically, livers in G3 group showed less hepatocytes necrosis, less bile duct hyperplasia and less collagen formation than in G4 and G5 groups. The protein expression levels of ACE2, ACE, AngII, AT1R and TGFβ1 in G2, G3 and G4 groups were significantly higher than in sham group (P<0.05), and lower than in G5 group (P<0.05). However, the differences among G2, G3 and G4 groups were not significant (P>0.05). ACE2 protein expression in G3 group was significantly higher than in G2 group (P<0.05) and there was no significant difference in comparison with G4 group (P>0.05). Moreover, the protein expression of TGFβ1 in G3 group was significantly lower than in G5 and G4 groups (P<0.05). Our findings suggest that the antifibrotic effects of YCHD may be associated with the decreased classical RAS pathway components and TGFβ1 downexpression so as to recover and rebuild self-regulation of the RAS by elevating the protein expression of ACE2.
Animals ; Disease Models, Animal ; Drugs, Chinese Herbal ; administration & dosage ; chemistry ; pharmacology ; Gene Expression Regulation ; drug effects ; Liver ; drug effects ; pathology ; Liver Cirrhosis ; metabolism ; pathology ; prevention & control ; Liver Function Tests ; Losartan ; administration & dosage ; Male ; Rats ; Rats, Sprague-Dawley ; Renin-Angiotensin System ; drug effects

Animals ; Colon ; blood supply ; pathology ; Colonic Diseases ; drug therapy ; etiology ; physiopathology ; Hemodynamics ; Hepatic Veins ; pathology ; physiopathology ; Hypertension, Portal ; complications ; physiopathology ; Intestinal Mucosa ; blood supply ; drug effects ; pathology ; Liver Cirrhosis, Experimental ; complications ; Losartan ; administration & dosage ; therapeutic use ; Male ; Microscopy ; Portal Pressure ; drug effects ; Random Allocation ; Rats ; Rats, Wistar

OBJECTIVETo investigate the origin of oxidative stress induced by angiotensin II (AngII) in human mesangial cells and the role of reactive oxygen species (ROS) in AngII-induced monocyte chemoattractant protein-1 (MCP-1) expression.

METHODSMCP-1 expression was determined by real time RT-PCR. ROS production was measured by DCFDA fluorescence. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was examined by lucigenin chemiluminescence. p47phox and p67phox translocation was assayed by Western blot. Twenty-four male mice were randomly divided into three groups: the control, the AngIIinfusion [AngII 400 ng/(kg.min)], and the apocynin treatment. AngII was infused by subcutaneously osmotic minipump for 14 days. Urinary albumin and 8-isoprostane excretion were measured by ELISA.

RESULTSIn cultured human mesangial cells, AngII induced the MCP-1 expression in a dose-dependent manner with 3.56 fold increase as compared with the control. AngII increased intracellular ROS production as early as 3 min with the peak at 60 min and was in a time and dose-dependent. Incubation with different dosages of AngII (1 nmol/L, 10 nmol/L, and 100 nmol/L AngII) for 60 min, ROS production increased at 1.82, 2.92, and 4.08 folds respectively. AngII-induced ROS generation was sensitive to diphenyleneiodonium sulfate (DPI, 10 micromol/L) and apocynin (500 micromol/L), two structurally distinct NADPH oxidase inhibitors. In contrast, inhibitors of other oxidant-producing enzymes, including the mitochondrial complex Iinhibitor rotenone, the xanthine oxidase inhibitor allopurinol, the cyclooxygenase inhibitor indomethacin, the lipoxygenase inhibitor nordihydroguiaretic acid, the cytochrome P450 oxygenase inhibitor ketoconazole and the nitric oxide synthase inhibitor G-nitro-L-arginine methyl ester were without an effect. AngII-induced ROS generation was inhibited by the AT1 antagonist losartan (10 micromol/L) but not the AT2 antagonist PD123319 (10 micromol/L). AngII treatment induced translocation of cytosolic of p47phox and p67phox to the membrane. The antioxidants almost abolished AngII-induced MCP-1 expression. AngII infusion increased urinary and p67 translocation by 2.69-, 2.97-, and 2.67-fold, respectively.

CONCLUSIONSNADPH oxidase-derived ROS is involved in AngII-induced MCP-1 expression. Inhibition of NADPH oxidase alleviates AngII-induced renal injury.

Acetophenones ; pharmacology ; Angiotensin II ; administration & dosage ; pharmacology ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Cells, Cultured ; Chemokine CCL2 ; metabolism ; Dose-Response Relationship, Drug ; Humans ; Losartan ; pharmacology ; Male ; Mesangial Cells ; metabolism ; Mice ; Mice, Inbred C57BL ; NADPH Oxidases ; antagonists & inhibitors ; metabolism ; Onium Compounds ; pharmacology ; Oxidative Stress ; Phosphoproteins ; metabolism ; Protein Transport ; Random Allocation ; Reactive Oxygen Species ; metabolism