Effects of eplerenone on expression and activity of aortic endothelial nitric oxide synthase in hypertensive rats induced by high-salt intake / 中国病理生理杂志

[ ABSTRACT] AIM:To explore the effects of eplerenone on the expression and activity of aortic endothelial nitric oxide synthase ( eNOS) in high salt-induced hypertensive rats .METHODS: Male Wistar rats (4 week old, weighting 50~60 g) were randomly divided into control group , high-salt diet group and eplerenone group .The rats in control group were fed with ordinary rodent animal diet , the rats in high-salt group and eplerenone group were exposed to 5%salt diet for 16 weeks and administrated with the same dosage of saline or eplerenone (40 mg? kg-1? d-1 ) by gavage for 4 weeks, re-spectively.Systolic blood pressure (SBP) was measured by tail-cuff every 2 weeks.The rats were sacrificed after 16 weeks and the thoracic aorta was collected .The aldosterone content in the aorta was measured by ELISA .The protein levels of mineralocorticoid receptor (MR) and eNOS were determined by Western blot.The activitie of constitutive NOS (cNOS) was measured by chemocolorimetry .The protein localization of eNOS , neuronal nitric oxide synthase ( nNOS) and MR was observed by immunohistochemistry .RESULTS: A process of 8-week high-salt diet increased SBP gradually .SBP in the rats exposure to high salt for 16 weeks was significantly higher than that in control group ( P<0.05 ) .After 4 weeks of eplerenone treatment, SBP in the rats was significantly lower than that before treatment (P<0.05).Compared with control group, the aldosterone content in the aorta were significantly increased in high-salt diet group and eplerenone group ( P<0.05), the expression level of MR also increased significantly (P<0.05).Compared with control group, both eNOS pro-tein expression (P<0.05) and cNOS activity in high-salt diet group were significantly decreased (P<0.05).The protein expression of eNOS as well as cNOS activity in aorta increased significantly in eplerenone group compared with high -salt diet group (P<0.05).CONCLUSION:Aldosterone content in aorta of high-salt-induced hypertensive rats increases signifi-cantly .Aldosterone attenuates the protein expression of eNOS and reduces the enzyme activity through the activation of min -eralocorticoid receptor .The selective mineralocorticoid receptor antagonist eplerenone enhances the protein expression of eNOS and its activity , thereby improves eNOS function .

Effects of hypoxia on endothelial nitric oxide synthase expression in cerebral artery endothelial cells / 中国病理生理杂志

AIM: To investigate the molecular mechanism by which hypoxia affect the endothelial nitric oxide synthase (eNOS) expression in cerebral artery endothelial cells (CAECs). METHODS: Primary cultured porcine CAECs were exposed to hypoxia for 2 h, 6 h, 12 h, 24 h and 48 h. The eNOS mRNA level was determined by RT-PCR. The level of eNOS protein was detected by Western blotting. After specific PKC inhibitors BIM Ⅰ(1 ?mol/L) and G6983 (1 ?mol/L) were added, CAECs were exposed to hypoxia for 24 h. The effect of hypoxia on eNOS mRNA stability was analyzed after actinomycin D was added. RESULTS: After exposure to hypoxia for 2 h, the levels of eNOS mRNA and protein in CAECs were increased. The levels of eNOS mRNA and protein reached peak after 12 h of hypoxia (about 2 5 fold and 2 0 fold, respectively, compared to control), and remained at higher level even after 48 h of hypoxia. Moreover, hypoxia did not change the stability of eNOS mRNA. The specific PKC inhibitors BIM Ⅰ and G6983 attenuated significantly the effects of hypoxia on eNOS gene expression. CONCLUSION: These results suggest that hypoxia may enhance the expression of eNOS gene in CAECs through PKC signaling pathway, which might be one of the mechanisms of cerebral artery dilation and neuroprotection during cerebral hypoxia.