Overview of endocrine systems in primary hypertension

Antioxidant Associated Antihypertensive Performance of Purified Gambir (Uncaria gambir Roxb.) on Prednisone Salt-Induced Hypertensive Rats

Introduction: Purified gambier (Uncaria gambir Roxb.) is potential for treating hypertension based on its antioxidant bioactivity. In this study, we investigated the antihypertensive performances of purified gambier on hypertensive rats and the correlation with its antioxidant activity. Methods: Rats (2-3 months old and the bodyweight of 200-250 g) were divided into five groups. Groups 1, 2, and 3 were treated orally with water suspension of purified gambier at doses of 2.5; 5; and 10 mg/kg BW once a day for 14 days, group 4 and 5 were acted as positive control (treated with vehicle) and captopril treated group (comparison) respectively.  The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), blood flow (BF) and blood volume (BV) were recorded once a day before and 1,3,7 and 14 days after commencement. The blood was taken before and at the end of recording for the plasma NO measurement. Two-way ANOVA was used to analyze the changes of those parameters, except for plasma NO analyzes by one-way ANOVA, followed by Duncan multirange test (95% confidence interval). Results: The study showed that significant antihypertensive effects (p<0.05), influenced by doses and gambier administration duration. The plasma NO of animals was increased after administration of purified gambier (p<0.05), although there was no significant difference in plasma NO in doses variation. Conclusion: These indicated that purified gambier proceed antioxidant associated antihypertensive effects  at doses of 2.5 – 10 mg/kg BW when administered for 14 days on the salt-prednisone induced hypertensive rats. KEYWORDS: antioxidant, antihypertensive, purified gambier, Uncaria gambir Roxb., salt-prednisone induced, hypertension rat

Phosphorylation at distinct subcellular locations underlies specificity in mTORC2-mediated activation of SGK1 and Akt

mTORC2 lies at the intersection of signaling pathways that control metabolism and ion transport through phosphorylation of the AGC-family kinases, the Akt and SGK1 proteins. How mTORC2 targets these functionally distinct downstream effectors in a context-specific manner is not known. Here, we show that the salt- and blood pressure-regulatory hormone, angiotensin II (AngII) stimulates selective mTORC2-dependent phosphorylation of SGK1 (S422) but not Akt (S473 and equivalent sites). Conventional PKC (cPKC), a critical mediator of the angiotensin type I receptor (AT₁R, also known as AGTR1) signaling, regulates the subcellular localization of SIN1 (also known as MAPKAP1) and SGK1. Inhibition of cPKC catalytic activity disturbs SIN1 and SGK1 subcellular localization, re-localizing them from the nucleus and a perinuclear compartment to the plasma membrane in advance of hormonal stimulation. Surprisingly, pre-targeting of SIN1 and SGK1 to the plasma membrane prevents SGK1 S422 but not Akt S473 phosphorylation. Additionally, we identify three sites on SIN1 (S128, S315 and S356) that are phosphorylated in response to cPKC activation. Collectively, these data demonstrate that SGK1 activation occurs at a distinct subcellular compartment from that of Akt and suggests a mechanism for the selective activation of these functionally distinct mTORC2 targets through subcellular partitioning of mTORC2 activity.

An assessment of the relationship between excess fluoride intake from drinking water and essential hypertension in adults residing in fluoride endemic areas

In this study, the relationships between high water fluoride exposure and essential hypertension as well as plasma ET-1 levels were investigated. A total of 487 residents aged 40 to 75 were randomly recruited from eight villages in Zhaozhou County from Heilongjiang Province in China and were divided into 4 groups according to the concentrations of fluoride in their water. Consumption levels of drinking water fluoride for normal, mild, moderate, and high exposure groups were 0.84±0.26 mg/L, 1.55±0.22 mg/L, 2.49±0.30 mg/L, and 4.06±1.15 mg/L, respectively. The prevalence of hypertension in each group was 20.16%, 24.54%, 32.30%, and 49.23%, respectively. There were significant differences between all the groups; namely, with the increase in water fluoride concentrations, the risk of essential hypertension in adults grows in a concentration-dependent manner. Significant differences were observed in the plasma ET-1 levels between the different groups (P<0.0001). In the multivariable logistic regression model, high water fluoride concentrations (F(-)≥3.01 mg/L, OR(4/1)=2.84), age (OR(3/1)=2.63), and BMI (OR(2/1)=2.40, OR(3/1)=6.03) were closely associated with essential hypertension. In other words, the study not only confirmed the relationship between excess fluoride intake and essential hypertension in adults, but it also demonstrated that high levels of fluoride exposure in drinking water could increase plasma ET-1 levels in subjects living in fluoride endemic areas.

Contribution of cytochrome P450 1B1 to hypertension and associated pathophysiology: a novel target for antihypertensive agents

The aim of this review is to discuss the contribution of cytochrome P450 (CYP) 1B1 in vascular smooth muscle cell growth, hypertension, and associated pathophysiology. CYP1B1 is expressed in cardiovascular and renal tissues, and mediates angiotensin II (Ang II)-induced activation of NADPH oxidase and generation of reactive oxygen species (ROS), and vascular smooth muscle cell migration, proliferation, and hypertrophy. Moreover, CYP1B1 contributes to the development and/or maintenance of hypertension produced by Ang II-, deoxycorticosterone (DOCA)-salt-, and N(ω)-nitro-L-arginine methyl ester-induced hypertension and in spontaneously hypertensive rats. The pathophysiological changes, including cardiovascular hypertrophy, increased vascular reactivity, endothelial and renal dysfunction, injury and inflammation associated with Ang II- and/or DOCA-salt induced hypertension in rats, and Ang II-induced hypertension in mice are minimized by inhibition of CYP1B1 activity with 2,4,3',5'-tetramethoxystilbene or by Cyp1b1 gene disruption in mice. These pathophysiological changes appear to be mediated by increased production of ROS via CYP1B1-dependent NADPH oxidase activity and extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Src.