AIMTo investigate whether the selective AT1 receptor antagonist irbesartan exerts neuroprotective effect on focal cerebral ischemia in normotensive rats.

METHODSCerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion, with the monitoring of laser Doppler flowmetry. To avoid the interaction with peripheral AT1 receptors, irbesartan was infused intracerebroventricularly (ICV) at a dose which effectively inhibited brain- but not vascular AT1 receptors. Neurological status was evaluated daily after MCAO. Rats were killed and brain samples were collected for the measurement of infarct size and immunohistochemical evaluation of apoptosis by deoxynucleotidyltransferase-mediated biotinylated UTP nick end labeling (TUNEL) and expression of activated Caspase-3 and the cleavage fragment of poly (ADP-ribose) polymerase (PARP).

RESULTSTreatment with irbesartan improved significantly the neurobehavioral functions after cerebral ischemia. The infarct size was reduced about 42% on day 7 after MCAO (P < 0.05). Meanwhile,irbesartan treatment significantly decreased the number of TUNEL-positive cells in the penumbra. The expression of activated Caspase-3 and the downstream cleavage fragment of poly (ADP-ribose) polymerase in the penumbra were also inhibited by irbesartan therapy on day 3 after transient cerebral ischemia.

CONCLUSIONAngiotensin AT1 receptor antagonist exhibits neuroprotection against transient cerebral ischemia in the brain. The neuroprotective effects in ischemic tissue may be associated with its inhibition of apoptotic cell death in the penumbra.

Angiotensin Receptor Antagonists ; pharmacology ; Animals ; Biphenyl Compounds ; pharmacology ; Cerebral Infarction ; pathology ; Ischemic Attack, Transient ; drug therapy ; pathology ; Lateral Ventricles ; Male ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Wistar ; Tetrazoles ; pharmacology

The purpose of study was to investigate the effects of L-arginine and cilostazol on platelet-activation and aggregation reserve in vitro, so as to provide proof for selecting reversible activation-inhibitors for platelets lyophilization. Activation and function of platelets were investigated by using flow cytometry with the CD62p and PAC-1 expression and re-expression after being activated by thrombin, and by means of platelet aggregation reaction to thrombin, ADP and propyl gallate, as well as coagulation activity of platelets. The results showed that expression of CD62p and PAC-1 increased after being pretreated. Both L-arginie and cilostazol could inhibit CD62p and PAC-1 expression and related with their concentrations. Cilostazol had an intensive inhibition effect on expressions of CD62p and PAC-1 induced by thrombin, and the inhibition increased when concentration augmented. L-arginine had the same effects on PAC-1, but had no effects on CD62p. L-arginine and cilostazol inhibited aggregation induced by thrombin, ADP and propyl gallate, and the inhibitions were related directly with dosage. When L-arginine concentration was higher or equal to 15 mmol/L, or cilostazol concentration was in range of 1 - 4 mmol/L, the aggregation time were prolonged so much or even no aggregation. It is concluded that when L-Arginine concentration is 5 mmol/L and 10 mmol/L, platelet activation can be inhibited, but aggregation ability and characters keep intact. Concentration at 5 mmol/L may be the best. 1 mmol/L of cilostazol can inhibit activation in vitro and retain part of platelet ability of aggregation and reexpression.
Arginine ; pharmacology ; Blood Platelets ; metabolism ; Humans ; P-Selectin ; drug effects ; metabolism ; Platelet Activation ; drug effects ; Platelet Aggregation ; drug effects ; Platelet Aggregation Inhibitors ; pharmacology ; Tetrazoles ; pharmacology

Ubiquitin-proteasome pathway (UPP) is one of the ways utilized for selective degradation of many proteins in cells, and the 20S proteasome takes the functional machinery where hydrolysis of targeted proteins takes place. Based on existing peptide inhibitors, a series of novel tripeptidic tetrazoles have been designed, synthesized, and the structures have been confirmed with 1H NMR, MS and elemental analysis. Among them, three compounds (6b, 6d and 6h) showed inhibitory activities of ChT-L of 20S proteasome.
Biological Assay ; Drug Design ; Molecular Structure ; Oligopeptides ; chemical synthesis ; chemistry ; pharmacology ; Proteasome Endopeptidase Complex ; chemistry ; Proteasome Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; Tetrazoles ; chemical synthesis ; chemistry ; pharmacology

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Collagen Type I ; biosynthesis ; Hepatocytes ; cytology ; metabolism ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

Benzimidazoles ; pharmacology ; Benzoates ; pharmacology ; Cell Proliferation ; drug effects ; Humans ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; drug effects ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives

OBJECTIVETo explore the pathogenic changes of myocardial apoptosis in heart hypertrophy during hypertension and evaluate the anti-apoptosis effect of Valsartan.

METHODSThirty spontaneously hypertensive rats (SHRs) were divided into two groups: 15 treated with Valsartan (20 mg x kg(-1) x d(-1)) (SHR + Valsartan group), the others with placebo (SHR + placebo group), with 15 normal Wistar rats as control. Systolic blood pressure was measured by the tail-cuff method. The observation period was from 8 to 16 weeks of age. Cardiac apoptosis was evaluated by a Terminal Deoxynucleotidyl Transferase-Mediated dUTP-biotin Nick End Labeling (TUNEL) assay.

RESULTSMean blood pressure values were 127 +/- 2 mm Hg in controls, 163 +/- 6 mm Hg in the SHR + Valsartan group and 193 +/- 7 mm Hg in the SHR + placebo group at 16 weeks of age, whereas the blood pressure in 8-week-old SHR and Wistar rats were 175 +/- 3 mm Hg and 125 +/- 5 mm Hg, respectively. The ratio of the heart weight over body weight declined in Wistar (3.07 +/- 0.03 mg/g) and SHR + Valsartan groups (3.22 +/- 0.19 mg/g) compared with the SHR + placebo group (4.02 +/- 0.31 mg/g) (P < 0.05). The density of TUNEL-positive cells in Wistar and SHR +/- Valsartan groups was 23.3 +/- 3.3 nuclei/HPF and 35.0 +/- 1.3 nuclei/HPF, both of which were significantly less than that of the SHR + placebo group (116.7 +/- 11.3 nuclei/HPF).

CONCLUSIONSIn response to chronic pressure overload, cardiomyocyte-specific apoptosis contributes to the transition from compensatory hypertrophy to decompensation. Apoptosis may be effectively inhibited by Valsartan in the early stage of hypertension.

Animals ; Antihypertensive Agents ; pharmacology ; Apoptosis ; drug effects ; Cardiomegaly ; pathology ; Hypertension ; pathology ; Myocardium ; cytology ; Rats ; Rats, Inbred SHR ; Rats, Wistar ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

OBJECTIVETo explore the effect of irbesartan on angiotensin-converting enzyme 2 (ACE2) mRNA expression in diabetic rat myocardium.

METHODSThirty 8-week-old male Wistar rats were randomly divided into control group (n=7), diabetic model group (n=14) and irbesartan group (n=9). Diabetes was induced by a single intraperitoneal injection of STZ (55 mg/kg), a blood glucose>16.7 mmol/L 72 h after the injection indicated successful establishment of diabetes. Four weeks after the modeling, the rats in irbesartan group were given 50 mg/kg irbesartan. ELISA was used to measure myocardial AngII content in the rats, and myocardial ACE2 mRNA expression was determined by real-time PCR.

RESULTSMyocardial AngII level in the diabetic model group was significantly higher than that in the control group (P<0.001). Irbesartan administration significantly lowered cardiac AngII levels in the diabetic rats (P<0.001). The rats in irbesartan group showed significantly increased myocardial ACE2 mRNA expression compared with those in the control and diabetic rat groups (P<0.05).

CONCLUSIONIrbesartan can increase ACE2 mRNA expression in the myocardium, which might be one of the mechanisms underlying its effect in improving the cardiac function in diabetic rats.

Animals ; Biphenyl Compounds ; pharmacology ; Diabetes Mellitus, Experimental ; enzymology ; Male ; Myocardium ; enzymology ; Peptidyl-Dipeptidase A ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Wistar ; Tetrazoles ; pharmacology

OBJECTIVETo evaluate the effect of irbesartan on the proliferation, apoptosis, and VEGF mRNA expression of human umbilical vein cell line EA.hy926 in vitro.

METHODSThe human umbilical vein cell line EA.hyY926 were treated with various concentrations of irbesartan for 24 h. The cell proliferation after the treatment was detected by CCK8 assay, flow cytometry and FITC Annexin V/PI kit were used to detect changes in the cell apoptosis. RT-PCR was used to evaluate the expression of VEGF mRNA.

RESULTSThere were no changes in cell shape with various concentration of irbesartan. CCK-8 assay showed a greater rate of the cell proliferation in irbesartan group than that in control group with a dose-independent manner after 24 h treatment. After incubation with irbesartan, cell proliferation rate was significant (P < 0.05). FCM analysis showed no significantly changes in the cell apoptosis. Irbesartan increased the proliferation of EA.hy926 cells. At concentration of 1 x 10(-4), 1 x 10(-5), 1 x 10(-6) mol/L, VEGF mRNA expression enhanced either (P < 0.05).

CONCLUSIONIrbesartan could promote the proliferation and up-regulated VEGFmRNA expression in EA.hy926 cell line. This result suggested that in addition to antihypertensive effect, angiotensin receptor antagonist might be a novel therapeutic approach to chronic ischemic heart disease as heart failure.

Apoptosis ; drug effects ; Biphenyl Compounds ; pharmacology ; Cell Line ; Cell Proliferation ; drug effects ; Humans ; RNA, Messenger ; genetics ; Tetrazoles ; pharmacology ; Umbilical Veins ; cytology ; metabolism ; Vascular Endothelial Growth Factor A ; metabolism

OBJECTIVETo investigate the relationship between the dosage of irbesartan and the renal tissue structure in diabetic rats.

METHODSMale Wistar rats was given a single intraperitoneal dose (mg/kg) of streptozotocin to induce diabetes. The diabetic rats were randomized into 4 groups and received 4 weeks later 25 mg/kg (n=9), 50 mg/kg (n=9), 200 mg/kg (n=9) irbesartan intragastrically, or equal volume of water (model group, n=11) on a daily basis. Seven normal rats receiving with equal volume of water served as the normal control. All the rats were sacrificed after 8 weeks and the 24-hour albumin excretion, renal mass index and the volume of the glomerulus were measured.

RESULTSThe 24-hour albumin excretion, renal mass index and volume of the glomerulus in the 3 irbesartan groups were significantly decreased as compare with those in the model group; the reductions in 50 and 200 mg/kg irbesartan groups were significant greater than those in 25 mg/kg irbesartan group.

CONCLUSIONIrbesartan can decrease the 24-hour urinary albumin excretion and relive glomerulopathy in diabetic rats. Within a certain dose range, irbesartan produces a dose-dependent protective effect on the renal structures in the diabetic rats.

Animals ; Biphenyl Compounds ; adverse effects ; pharmacology ; Diabetes Mellitus, Experimental ; pathology ; Dose-Response Relationship, Drug ; Kidney ; pathology ; Male ; Rats ; Rats, Wistar ; Tetrazoles ; adverse effects ; pharmacology

OBJECTIVETo investigate of the regulatory effect of Rho-kinase pathway activation on angiotensin II (Ang II)-induced contraction of human airway smooth muscle cells (HASMCs) in vitro.

METHODSCultured primary HASMCs were divided into control group, AngII group, AngII + irbesartan group and AngII + Y-27632 group with corresponding treatment. AngII-induced contraction of HASMCs was evaluated using collagen gel lattices and observed morphologically using immunofluorescence assay. Western Blotting was significantly performed to examine the protein expression of Rho-kinase signal pathway.

RESULTSAngII-induced HASMC contraction was inhibited by treatments with irbesartan and Y-27632 as shown by gel contraction assay (P<0.001). Y-27632 treatment produced a stronger inhibitory effect than irbesartan on the expression of phosphorylated moesin, a substrate of Rho kinase (P<0.05).

CONCLUSIONAngII induces the contraction of HASMCs partially as a result of activation of Rho-kinase pathway.

Amides ; pharmacology ; Angiotensin II ; pharmacology ; Asthma ; physiopathology ; Biphenyl Compounds ; pharmacology ; Bronchi ; cytology ; Humans ; Muscle Contraction ; drug effects ; Muscle, Smooth ; cytology ; Primary Cell Culture ; Pyridines ; pharmacology ; Signal Transduction ; drug effects ; Tetrazoles ; pharmacology ; rho-Associated Kinases ; metabolism