Animals ; Antihypertensive Agents ; pharmacology ; Heme Oxygenase (Decyclizing) ; drug effects ; metabolism ; Losartan ; pharmacology ; Rats ; Water-Electrolyte Balance

Interleukin (IL)-6 is an autocrine growth factor for mesangial cells. It is not known whether high glucose influences IL-6 production in mesangial cells. Angiotensin II (AGII) is involved in the progression of renal diseases including diabetic nephropathy. Therefore, we evaluated the effects of high glucose in concert with AGII on IL-6 production in human mesangial cells and the modulation by blocking AGII. After 48 hr of culture, IL-6 mRNA expression was analyzed by reverse transcription and polymerase chain reaction (PCR). Quantitative determination of IL-6 concentrations in the culture supernatants of mesangial cells was performed using a sandwich enzyme immunoassay kit. Incubation of mesangial cells with high glucose (450 mg/dL) reduced the ratio of PCR products for IL-6 to beta-actin on densitometric results, while AGII (10(-7)M) increased it. The IL-6 secretion in the supernatant was also increased by AGII and decreased by high glucose. The IL-6 mRNA expression and IL-6 secretion in combination of high glucose and AGII were higher than those in high glucose and similar with those in control media. The addition of losartan (10(-6)M) or captopril (10(-6)M) to high glucose had no additional effects on IL-6 production. These results suggest that whereas AGII increases IL-6 production, high glucose decreases it. The IL-6 production of mesangial cells in diabetic milieu may be complicated and depend on the local effects of high glucose and/or AGII.
Angiotensin II/*pharmacology ; Captopril/pharmacology ; Cells, Cultured ; Gene Expression/drug effects ; Glomerular Mesangium/cytology/*metabolism ; Glucose/*pharmacology ; Humans ; Interleukin-6/*biosynthesis/genetics/secretion ; Losartan/pharmacology

AIM AND METHODSTo investigate the effect of 2 mg/kg and 10 mg/kg losartan intraperitoneally (i.p) on arterial blood pressure (AP) and heart rate (HR) in rat and the involvement in the activity of habenulas neurons. Glass micropipette was used to record any changes of unit discharging of neurons in LHb and MHb before and after losartan was intraperitoneally injected.

RESULTSAP and HR were not significantly changed by 2 mg/kg losartan (i.p). However, AP was apparently decreased by 10 mg/kg losartan (i.p), but HR was unchanged. After 10 mg/kg losartan (i.p), 66.66% (12/18) unit discharging of neurons in LHb were increased in frequency, and 61.90% (13/21) in MHb were decreased.

CONCLUSIONAP of rat was significantly decreased by 10 mg/kg losartan (i.p). Depressor effect of losartan (i.p) was involved in the excision of neurons in LHb and the inhibition in MHb.

Animals ; Blood Pressure ; drug effects ; Habenula ; drug effects ; physiology ; Losartan ; pharmacology ; Neurons ; drug effects ; physiology ; Rats ; Rats, Wistar

AIM AND METHODSThe effects of losartan (after operation 2 week to 10 week, 5 mg/kg d ig) on generation of AT1R-AA in sera were observed during development of hypertension in rats. The renovascular hypertension (RVH) model was established by two-kidney one-clip method, a synthetic peptide corresponding to amino acid sequence 165-191 of the second extracellular loop of the angiotensin II-1 receptor (AT1R) was used as antigen, SA-ELISA were used to examine sera AT1R autoantibody (AT1R-AA).

RESULTSThe frequencies and titres of AT1R-AA after operation one week rats were significantly increased (P < 0.05). The treatment with losartan not only inhibited structural and functional changes, but also the frequencies and titres of AT1R-AA was significantly lower (P < 0.05) than RVH group.

CONCLUSIONIt is suggested that the losartan significantly inhibits generation of the AT1R-AA.

Animals ; Autoantibodies ; biosynthesis ; blood ; Hypertension, Renovascular ; blood ; immunology ; Losartan ; pharmacology ; Male ; Rats ; Rats, Wistar ; Receptors, Angiotensin ; immunology

BACKGROUNDAtrial electrical remodeling (AER) contributes to the maintainance of atrial fibrillation (AF). This study was to compare the effects of Losartan with those of Diltiazem on tachycardia-induced acute AER in rabbits.

METHODSTwenty-one rabbits paced with maximal atrial capture rate for 3 hours in the right atrium (RA) were randomly divided into saline group, Diltiazem group and Losartan group. After autonomic blockage, we measured atrial effective refractory period (AERP), AERP rate adapting feature, AERP dispersion and RA conduction time at basic cycle lengths (BCLs) of 200 ms and 150 ms at baseline, 0.5 hour, 1 hour, 2 and 3 hours after rapid atrial pacing.

RESULTSIn the saline group, there was a prompt decrease in AERP as a result of rapid atrial pacing, and AERP200 and AERP150 were shortened sharply within 0.5 hour of pacing (30.2 +/- 10.5 ms and 24.1 +/- 9.1 ms, respectively). The AERP did not change dramatically in the Diltiazem and Losartan groups. In the saline group, the value of (AERP200-AERP150)/50 ms in high RA was 0.17 +/- 0.08 at baseline and became significantly smaller at 0.5 hour (0.08 +/- 0.06), 1 hour (0.09 +/- 0.06), 2 hours (0.08 +/- 0.04) and 3 hours (0.09 +/- 0.05) (all P < 0.05), suggesting a reduction of rate adaptation of AERP. The value of (AERP200-AERP150)/50 ms in high RA did not change during the 3 hours of pacing in both Diltiazem and Losartan groups. In the saline group, AERP dispersion increased significantly at 2 and 3 hours (P < 0.05). However, Diltiazem could not prevent the increase of AERP dispersion at 3 hours (P < 0.05). During Losartan infusion, the AERP dispersion was no longer increased after rapid atrial pacing. There was no significant difference in RA conduction time among the three groups.

CONCLUSIONLike calcium antagonist Diltiazem, Losartan could prevent AERP shortening and preserve rate adaptation of AERP after rapid atrial pacing. Losartan is more effective than Diltiazem in inhibiting the increase of AERP dispersion.

Animals ; Atrial Fibrillation ; drug therapy ; physiopathology ; Calcium ; metabolism ; Cardiac Pacing, Artificial ; Diltiazem ; pharmacology ; Heart Conduction System ; drug effects ; physiopathology ; Losartan ; pharmacology ; Rabbits ; Refractory Period, Electrophysiological ; drug effects

OBJECTIVETo investigate the expression of Toll-like receptor 4 (TLR4) in the liver tissue of rats with bile duct ligation (BDL)-induced hepatic fibrosis and evaluate the inhibitory effects of perindopril and losartan on TLR4 expression.

METHODSMale Wistar Rats were randomly divided into sham-operated group (n=6), BDL group, perindopril treatment group (2 mg/kg) and losartan treatment group (50 mg/kg) (n=12). Perindopril and losartan groups were further divided into two subgroups for corresponding treatments by gastric lavage once daily for 14 and 30 days. The protein level of TLR4 in the liver tissue was examined by Western blotting.

RESULTSIn 14-day BDL group, the protein level of TLR4 significantly increased to 6.53∓1.11 folds of that in the sham group (P<0.05), and was lowered significantly to 1.71∓0.41 folds and 0.95∓0.38 folds following perindopril and losartan treatments for 14 days. TLR4 expression significantly increased to 6.51∓0.87 folds and 5.64∓0.87 folds of that of the sham group in perindopril and losartan groups after the 30-day treatments (P<0.05).

CONCLUSIONTLR4 expression is up-regulated in the liver of rats with BDL-induced hepatic fibrosis, and can be lowered by perindopril and losartan treatmemts for 14 days.

Animals ; Bile Ducts ; surgery ; Down-Regulation ; drug effects ; Ligation ; Liver Cirrhosis, Experimental ; metabolism ; pathology ; Losartan ; pharmacology ; Male ; Perindopril ; pharmacology ; Rats ; Rats, Wistar ; Toll-Like Receptor 4 ; genetics ; metabolism

The study is to investigate the effect of angiotensin II (Ang II) and its receptor blockers on migration and endothelin-1 (ET-1) expression of rat vascular adventitial fibroblast subpopulations. Vascular adventitial fibroblasts were individually expanded by using cloning rings, and the effects of Ang II on the migration of adventitial fibroblast subpopulations were evaluated by Transwell. Fluorescence quantitative-PCR detected the expression of preproET-1 mRNA induced by Ang II, and its receptor antagonists losartan and PD-123319. The concentration of ET-1 was determined by ELISA. It showed that spindle shaped and epithelioid shaped cells were isolated by using cloning rings, named as spindle cells and round cells. RT-PCR showed that fibroblast subpopulations did not have leukocytes, endothelial cells and smooth muscle cells, namely pure cell lines. Compared with respective control cells, two subpopulations had transferring ability. Ang II significantly improved round cells migration in a concentration-dependent manner, and had no obvious influence on spindle cells migration. Ang II (1 x 10(-8) - 1 x 10(-6) mol x L(-1)) significantly increased the expression of preproET-1 mRNA in round cells (P < 0.01), and had no significant effect on the expression of preproET-1 mRNA in spindle cells. Losartan blocked the expression of preproET-1 mRNA induced by Ang II in round cells, and had no significant effect on the expression of preproET-1 mRNA in spindle cells. The effects of Ang II and ET-1 receptor inhibitors on the release of ET-1 were similar to the expression of preproET-1 mRNA. The results indicate that there are two cell subpopulations: round cells and spindle cells in rat vascular adventitial fibroblasts. Ang II significantly improved cells migration, and increased the expression of ET-1 in round cell subpopulation. It suggested that there may be different migratory mechanisms in two cell subpopulations, and the two subpopulations may play a different role in vascular remodeling and reparative process.
Angiotensin II ; pharmacology ; Angiotensin Receptor Antagonists ; pharmacology ; Animals ; Cell Movement ; drug effects ; Cells, Cultured ; Endothelin-1 ; genetics ; metabolism ; Fibroblasts ; cytology ; metabolism ; Imidazoles ; pharmacology ; Losartan ; pharmacology ; Male ; Pyridines ; pharmacology ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasoconstrictor Agents ; pharmacology

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 investigate the effect of losartan on the expression of monocyte chemoattractant protein-1 (MCP1) and transforming growth factor-β(1) (TGF-β(1)) in the kidney of rats with unilateral urethral obstruction (UUO) and evaluate protective effect of losartan against reanal interstitial fibrosis.

METHODSRat models of UUO were treated with losartan at the routine dose, high dose, and very high dose (50, 200, and 500 mg/kg daily, respectively), and saline was given to UUO model rats and rats with sham operation. At 7, 14, and 21 days, the tail cuff blood pressure (TCP), 24-h urine protein (Upro), serum Scr, BUN, K(+), percentage of renal damage and renal interstitial fibrosis (%INT) were measured in the rats. MCP1 protein in the renal tissues was detected using immunohistochemistry, and MCP1 and TGF-β(1) mRNA expressions were assayed using RT-PCR.

RESULTSAs the UUO prolonged, Upro, TCP, tubular damage, %INT, and MCP1 and TGF-β(1) mRNA expressions all increased significantly (P<0.05). High and very high doses of losartan, compared with the routine dose, obviously reversed these changes.

CONCLUSIONHigh-dose losartan can effectively control blood pressure, reduce renal damage and fibrosis, and inhibit MCP1 and TGF-β(1) expression in rats with UUO, and at a very high dose, losartan can more effectively reduce 24-h Upro than the high-dose group. High and very high doses of losartan offer better protective effect on the kidney in rats with UUO.

Animals ; Chemokine CCL2 ; metabolism ; Fibrosis ; etiology ; prevention & control ; Kidney ; metabolism ; pathology ; Losartan ; pharmacology ; Male ; Rats ; Rats, Sprague-Dawley ; Transforming Growth Factor beta1 ; metabolism ; Ureteral Obstruction ; complications ; drug therapy

OBJECTIVETo observe the reconstruction features of adventitia in senescent rats, and to explore the intervention mechanism of Chinese herbs (CH, extracts from Radix Ginseng, Radix Notoginseng, and Rhizoma Chuanxiong).

METHODSTotally 85 20-month senescent rats were randomly divided into 5 groups according to body weight, i.e., the aging model group, the high dose CH group, the middle dose CH group, the low dose CH group, the Losartan group, 17 in each group. Another 14 2-month old Wistar rats were selected as a young group. Extracts of CH at the daily dose of 1493. 4, 746. 7, and 373. 4 mg/kg were administered to rats in the 3 CH groups respectively by gastrogavage. Losartan suspension at the daily dose of 10 mg/kg was administered to rats in the Losartan group by gastrogavage. Equal volume of distilled water was administered to rats in the aging model group and the young group. All medication was performed once daily. After 15-week intervention, morphological changes of thoracic aorta were observed by HE staining. The types, distribution, and contents of vessel wall collagens were determined using picric acid picrosirius red staining. The plasma renin activity (PRA) , the concentration of rennin angiotensin II (Ang II), and the content of Ang II in adventitia were detected by radioimmunoassay. The content of hydroxyproline ( Hyp) was detected by biochemical analysis. mRNA contents and protein expressions of angiotensin II receptor 1 (AT1R) and angiotensin II receptor 2 (AT2R) were detected by real-time PCR (RT-PCR) and Western blot.

RESULTSCompared with the young group, thickened adventitia, increased adventitia thickness/caliber, accumulated collagen fiber, increased area of type I collagen, decreased area of type III collagen, decreased type III/I collagen area ratio (P <0. 05), decreased plasma PRA and Ang II (P < 0.01, P < 0.05), increased contents of Ang II and Hyp in adventitia, down-regulated mRNA and protein expressions of AT1R, and up-regulated mRNA and protein expression of AT2R could be seen in the aging model group (P < 0.05). Compared with the aging model group, morphological changes could be improved in the 3 CH groups. Adventitia thickness/caliber was reduced in middle and high dose CH groups, as well as the Losartan group. The area of type I collagen was reduced and the area of type III collagen was enlarged, type III/I collagen area ratio obviously increased, contents of adventitia Hyp was obviously lowered in the high dose CH groups and the Losartan group (P < 0.05, P < 0.01). Ang II levels in adventitia decreased in middle and high dose CH groups and the Losartan group (P < 0.05, P < 0.01). There was no statistical difference in PAR among all groups (P > 0.05). Compared with the aging model group, mRNA expression of AT1R all increased in each treatment group (P < 0.01); mRNA expression of AT2R also increased in middle and high dose CH groups (P < 0.05). Protein expression of AT1R increased in the high dose CH group and the Losartan group (P < 0.01, P < 0.05); protein expression of AT2R also increased in middle and high dose CH groups (P < 0.05).

CONCLUSIONSAdventitia remodeling occurred in aged rats, manifested as thickened adventitia and accumulated collagens, disordered ratios of collagen I and III. Its mechanism might be possibly associated with aactivation of renin-angiotensin system (RAS). Extracts from Radix Ginseng, Radix Notoginseng, and Rhizoma Chuanxiong could improve adventitial remodeling possibly by interfering multi-targets, such as Ang II and AT1R, thereby delaying vascular aging.

Adventitia ; drug effects ; Aging ; Angiotensin II ; Animals ; Aorta, Thoracic ; Drugs, Chinese Herbal ; pharmacology ; Losartan ; Panax ; Plant Roots ; RNA, Messenger ; Rats ; Rats, Wistar ; Renin-Angiotensin System ; Rhizome