BACKGROUND: Angiotensin Ⅱ (Ang Ⅱ) can induce cardiac hypertrophy and platelet-derived growth factor(PDGF) also stimulates cardiac hypertrophy. Is AngⅡ responsible for the pathogenesis of cardiac hypertrophy by inducing PDGF receptor expression?OBJECTIVE: To investigate the effect of mitogen activated protein kinase (MAPK) on the role of cardiac hypertrophy induced by Ang Ⅱ in cardiac myocytes so as to provide theoretical basis for clinical prevention and cure of cardiac hypertrophy.DESIGN: Controlled experimental study taking cardiac myocytes of cultured neonatal rats as subjects.SETTING: Department of pathophysiology in a university.MATERIALS: The experiment was completed in the Department of Pathophysiology, Medical College of Peking University. A total of 80 Wistar rats of either gender, aged 1 - 3 days, were provided by the Animal Center of Medical College, Peking University. Their hearts were removed for myocyte culture in the Cell Culture Laboratory.INTERVENTIONS: The cultured neonatal rat cardiac myocytes treated with 10-7mol/L Ang Ⅱ were Ang Ⅱ group, and those preincubated with 10-5mol/L PD98059(an antagonist of MAPK) for 30 minutes and then treated with Ang Ⅱ were PD98059 group. Cardiac myocytes of normal neonatal rats were as control group. The expression of PDGF-β was detected by western blot at 24 hours.MAIN OUTCOME MEASURES: Content of PDGF-β receptor in neonatal rat cardiac myocytes.RESULTS: The expression of PDGF-β receptor induced by Ang Ⅱ at neonatal rat cardiac myocytes markedly increased at 24 hours (432.41 ± 54.08) compared with that of control group(197.65 ± 44. 10) ( q = 6.77, P< 0.01 ). PDGF-β receptor expression of PD98059 group(317.2 ± 21.12) decreased compared with that of Ang Ⅱ group(q = 3.91, P < 0.05) .However, the expression did not return to the level of control group, and there was significant difference between PD98059 group and control group( q= 3.85, P <0.05).CONCLUSION: The results indicate that angiotensin Ⅱ promotes cardiac hypertrophy through inducing expression of PDGF receptor, in which mitogen activated protein kinase participates in. Maybe it is another important mechanism for Ang Ⅱ -induced cardiac hypertrophy. The results can provide experimental data for the primary and secondary prevention in heart rehabilitation.

AIM: To investigate the crosstalk between angiotensin Ⅱ (AngⅡ)-mediated and platelet-derived growth factor (PDGF)-mediated signal transduction in vascular smooth muscle proliferation.METHODS: A model of renal hypertension was made by two kidney/one-clip operation. Level of PDGF receptor β subunit of aorta was measured by Western Blot analysis. The effect of Ang Ⅱ on PDGF receptor β subunit expression was investigated in culture rat aortic vascular smooth muscle cells (VSMC).RESULTS: Systolic blood pressure obviously increased at 8th week after operation, whereas the level of PDGF receptor β subunit of aorta significantly increased by 126.6% (P＜0.05) in 2K1C rats compared with control group. The expression of PDGF receptor β subunit in cultured VSMC stimulated by AngⅡ was higher than that of control by 192.74%(P＜0.01). The effect of AngⅡ was inhibited remarkably by pretreated with losartan, a kind of specific AngⅡ receptor 1 (AT1) subtype antagonist and U73122, a kind of phospholipase C inhibitor. The effect was partly blocked by PD98059, which inhibit the activity of mitogen-activated, ERK-activating kinase (MEK).CONCLUSION: AngⅡ-induced PDGF receptor β subunit expression is regulated by the AT1 and its downstream signal molecule-PLC and ERK, might participate in the intracellular signal transduction pathway.

AIM: To investigate the crosstalk between angiotensin Ⅱ (AngⅡ)-mediated and platelet-derived growth factor (PDGF)-mediated signal transduction in vascular smooth muscle proliferation.METHODS: A model of renal hypertension was made by two kidney/one-clip operation. Level of PDGF receptor ? subunit of aorta was measured by Western Blot analysis. The effect of Ang Ⅱ on PDGF receptor ? subunit expression was investigated in culture rat aortic vascular smooth muscle cells (VSMC).RESULTS: Systolic blood pressure obviously increased at 8th week after operation, whereas the level of PDGF receptor ? subunit of aorta significantly increased by 126.6% ( P

AIM: To investigate the role of G?q/11-mediated signal transduction pathway in cardiac hypertrophy induced by angiotensin II (AngII). METHODS: Renal hypertension was performed by placing a sliver clip around the left renal artery(2K1C). Hemodynamic parameters, the ratio of left ventricular weight to body weight, the AngII contents and the activities of phospholipase C (PLC) in myocardium were measured at 1st, 2nd, 4th and 8th week after operation, respectively. The levels of G?q/11 were assayed by Western blot analysis. -leucine incorporation and levels of G?q/11 were measured in cultured neonatal rats ventricular myocyte after AngII stimulation. RESULTS: In 2K1C group, blood pressure and the ratio of left ventricle of heart to body weight were significantly increased compared with sham group between 2nd to 8th week. AngII content increased from 1st to 8th week after operation. Compared with the sham group, levels of G?q/11 in 2K1C group increased by 25.0% and 35.8% at 4th and 8th week( P

AIM: To investigate the changes of G?q/11 and phospholipase C(PLC) of the aorta and to evaluate the role of signal transduction pathway mediated by G?q/11 in the pathogenesis of spontaneous hypertension. METHODS: Blood pressure was measured by intubation of carotid, and the level of plasma angiotension Ⅱ was measured by radioimmunoassay. In addition, G?q/11 and PLC contents in aorta were determined by Western blot analysis. RESULTS: Arterial blood pressure was not changed in 4-week-old spontaneously hypertensive rats(SHR), but it was increased markedly in 12-week-old SHR. The G?q/11 expression of aorta in 4-week-old SHR was increased by 69 2%( P

Objective To explore the action mechanism of tauroursodeoxycholic acid(TUDCA)promoting intracellular clearance of Burkholderia pseudomallei(B.pseudomallei)in RAW264.7 macrophages.Methods After TUDCA of different concentrations were used to treat RAW264.7 cells pre-infected with B.pseudomallei for 8 h or not,flow cytometry was applied to detect the apoptosis of the infected and control cells.In addition,another endoplasmic reticulum stress(ERS)inhibitor 4-PBA was used to detect the apoptosis and proliferation of host cells after B.pseudomallei infection with Annexin-V/PI double staining and MTT cell proliferation assay.Furthermore,after transfected with CHOP siRNA,Western blotting and flow cytometry were employed to detect the effect of TUDCA on the expression levels of Caspase-3 and Caspase-12 and the changes in apoptotic rate after B.pseudomallei infection,respectively.Finally,the effect of TUDCA on intracellular multiplication of infected RAW264.7 cells were observed to estimate the CFU value in the presence and absence of CHOP siRNA.Results Under different concentrations of TUDCA,100 or 200 μmol/L TUDCA significantly reduced B.pseudomallei-induced apoptosis in RAW264.7 cells(P＜0.05).Meanwhile,both TUDCA and 4-PBA treatment could decrease the apoptosis induced by B.pseudomallei infection by ERS(P＜0.05).Further,the expression levels of Caspase-3 and Caspase-12 were obviously increased after B.pseudomallei infection compared with uninfected groups,but their expression levels in the siCHOP group was significantly lower than that in the siC group.Besides,flow cytometry also showed that TUDCA could reduce apoptosis induced by B.pseudomallei infection(P＜0.05),but no significant effect of TUDCA on apoptosis was observed under CHOP knockdown.Finally,intracellular CFU assay indicated that TUDCA treatment promoted the host cell clearance of B.pseudomallei(P＜0.05),but no such effect was observed in siCHOP group.Conclusion In B.pseudomallei infected RAW264.7 cells,TUDCA promotes the intracellular clearance of the bacteria by inhibiting ERS-induced apoptosis.