Faculty Opinions recommendation of Novel role of fumarate metabolism in dahl-salt sensitive hypertension.

Author(s):  
Daniel Beard
2019 ◽  
Vol 20 (14) ◽  
pp. 3495 ◽  
Author(s):  
Yanling Yan ◽  
Jiayan Wang ◽  
Muhammad A. Chaudhry ◽  
Ying Nie ◽  
Shuyan Sun ◽  
...  

We have demonstrated that Na/K-ATPase acts as a receptor for reactive oxygen species (ROS), regulating renal Na+ handling and blood pressure. TALLYHO/JngJ (TH) mice are believed to mimic the state of obesity in humans with a polygenic background of type 2 diabetes. This present work is to investigate the role of Na/K-ATPase signaling in TH mice, focusing on susceptibility to hypertension due to chronic excess salt ingestion. Age-matched male TH and the control C57BL/6J (B6) mice were fed either normal diet or high salt diet (HS: 2, 4, and 8% NaCl) to construct the renal function curve. Na/K-ATPase signaling including c-Src and ERK1/2 phosphorylation, as well as protein carbonylation (a commonly used marker for enhanced ROS production), were assessed in the kidney cortex tissues by Western blot. Urinary and plasma Na+ levels were measured by flame photometry. When compared to B6 mice, TH mice developed salt-sensitive hypertension and responded to a high salt diet with a significant rise in systolic blood pressure indicative of a blunted pressure-natriuresis relationship. These findings were evidenced by a decrease in total and fractional Na+ excretion and a right-shifted renal function curve with a reduced slope. This salt-sensitive hypertension correlated with changes in the Na/K-ATPase signaling. Specifically, Na/K-ATPase signaling was not able to be stimulated by HS due to the activated baseline protein carbonylation, phosphorylation of c-Src and ERK1/2. These findings support the emerging view that Na/K-ATPase signaling contributes to metabolic disease and suggest that malfunction of the Na/K-ATPase signaling may promote the development of salt-sensitive hypertension in obesity. The increased basal level of renal Na/K-ATPase-dependent redox signaling may be responsible for the development of salt-sensitive hypertension in polygenic obese TH mice.


Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Bernardo Lopez ◽  
Galina Petrova ◽  
Justine M Abais-Battad ◽  
Hayley Lund ◽  
Daniel Fehrenbach ◽  
...  

Epidemiological data indicates that acute kidney injury (AKI) is an independent risk factor for the development of hypertension and chronic kidney disease in patients. Previous studies demonstrated that rats develop sodium-dependent hypertension and kidney damage following experimental AKI induced by a renal ischemia-reperfusion (IR) insult; furthermore, these high salt deleterious effects could be blunted by administration of immunosuppressive agents. The present study was performed on Dahl SS (SS) rats and SS rats with a null mutation in the CD247 gene (SS-CD247) leading to depletion of T-lymphocytes in order to specifically examine the role of T cells in this response (n=5-6 rats/group). As assessed by serum creatinine (SCr) levels, no difference was observed in the initial response to IR injury between SS and SS-CD247: SCr increased from 0.44±0.03 to 2.16±0.32 mg/dl in SS rats 24 hours after an initial 30 minute period of renal ischemia and returned to control levels after 8 days of recovery. Moreover, no differences were noted in mean arterial pressure (MAP) or albumin excretion rate (UAlb) between SS and SS-CD247 after 43 days of recovery from IR injury while the rats were maintained on a low salt (0.4% NaCl) diet. When the rats were fed a 4.0% NaCl diet for two weeks, MAP and UAlb significantly increased in the sham SS to 178±9 mmHg and 189±25 mg/day, respectively; values significantly greater than observed in the sham SS-CD247 rats (148±2 mmHg and 87±17 mg/day). As expected, the SS rats recovered from IR injury demonstrated an exaggerated increase in MAP (peaking at 183±2 mmHg) and UAlb (275±54 mg/day) in response to high salt. There was no difference in the number of total CD3+ lymphocytes in the kidneys of IR and sham SS after high salt, though the ratio of CD4+/CD8+ T cells was increased in the IR group. Compared to sham CD247, an exaggerated elevation of MAP (157±9 mmHg) and UAlb (210±32 mg/day) was also observed in the SS-CD247 rats recovered from IR injury, demonstrating enhanced responsiveness following IR injury in animals lacking T cells. These data indicate that T lymphocytes amplify salt-sensitive hypertension and renal damage, but other mechanisms also mediate the salt-sensitive hypertension and renal damage that occurs in animals recovered from IR injury.


Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Amrita V Pai ◽  
Crystal A West ◽  
Aline Souza ◽  
Parnika S Kadam ◽  
Emma J Pollner ◽  
...  

Introduction: Several studies in Dahl salt-sensitive ( DS ) rats suggest that T cells play a role in salt-sensitive hypertension. To further investigate the role of T cells, we compared T cell profiles in hypertensive DS and normotensive Dahl salt-resistant ( DR ) rats as well as in DS rats treated with hydralazine ( HYD ) to attenuate the development of hypertension. Methods: Mean arterial pressure ( MAP ) was measured by telemetry in DS rats (n=13) from 1 to 4.5 months ( mo ) of age. At 1.5 mo, all of the DR (n=8) and half of the DS rats were treated with vehicle (VEH, n=7). The other half of the DS rats (n=6) received HYD (25 mg/kg/day) in the drinking water. At 4.5 mo, renal T helper ( Th ) and cytotoxic ( Tc ) cells were assessed by multicolor flow cytometry. Results: In the DS kidney, the frequency of CD4 + Th cells [(%): DS-VEH, 76±1.2* vs. DR-VEH, 55±0.7; *p<0.0001; n=7-8/group] was higher while the frequency of CD8 + Tc cells [(%): DS-VEH, 14±1.2* vs. DR-VEH, 35±1; *p<0.0001; n=7-8/group] was lower compared to DR rats. 10 weeks of HYD treatment attenuated the age-associated increase in MAP observed in DS rats [p<0.0001, Two-Way ANOVA (time, treatment); MAP (mmHg): DS-VEH, 157±4 vs. DS-HYD, 133±3; *p<0.0004; n=6-7/group]. HYD had no effect on the frequency of CD4 + [(%):77±1.5] or CD8 + [(%):15.5±0.9] T cells in the kidney of DS rats [(CD4 + ): DS-VEH vs. DS-HYD, p=0.83; (CD8 + ): DS-VEH vs. DS-HYD, p=0.5; n=7-8/group]. In summary, the ratio of Th (CD4 + ) to Tc (CD8 + ) cells is higher in the kidney of DS compared to DR rats and HYD had no effect on the T cell profile in the DS rat kidney under conditions in which the MAP was attenuated by 20 mm Hg. Conclusions: These findings indicate the DS rat has more active Th cells in the kidney compared to the DR rat. Our study also suggests that vasodilators can attenuate the development of hypertension in the DS rat in a Th- and Tc-independent manner.


Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Rohan U Parekh ◽  
Abdel A Abdel-rahman ◽  
Srinivas Sriramula

Hyperactivity of the orexin system contributes to several animal models of hypertension and enhances arginine vasopressin (AVP) release. We previously reported higher neuronal kinin B1 receptor (B1R) expression and brain AVP levels in hypertensive mice. However, the role of B1R and its interaction with orexin system in neurogenic hypertension have not been studied. In the present study, we tested the hypothesis that kinin B1R contributes to hypertension by upregulation of orexin-AVP signaling in the brain. Deoxycorticosterone acetate (DOCA)-salt treatment (1 mg/g body weight DOCA, 1% saline in drinking water, 3 weeks) of wild-type (WT) male mice produced a significant increase in mean arterial pressure (MAP; radio-telemetry) (138 ±3 mmHg, n=8, p<0.01) that was blunted in B1R knockout mice (121±2 mmHg, P <0.05 vs. WT+DOCA). In WT mice, DOCA-salt, compared to vehicle, increased mRNA levels of orexin receptor 1 (2.5 fold, n=9, p<0.001), orexin receptor 2 (3 fold, n=9, p<0.001) and AVP (3 fold, n=9, p<0.01) in the hypothalamic paraventricular nucleus (PVN), and these DOCA-salt evoked effects were attenuated in B1RKO mice. Similarly, DOCA-salt evoked increases in protein expression of orexin receptor 1 and 2 in the hypothalamic PVN of WT mice were attenuated by 25±5% and 33±5% (p<0.05), respectively, in B1RKO vs WT+DOCA mice. Furthermore, DOCA-salt treatment increased plasma AVP levels in WT mice compared to vehicle treated mice (13.69±1.1 vs. 47.86±8.7 pg/ml, p<0.05), but not in B1RKO mice. Together, these data provide novel evidence that kinin B1R plays an important role in mediating DOCA-salt induced hypertension possibly via upregulating the orexin-AVP signaling in the brain.


2019 ◽  
Vol 316 (6) ◽  
pp. H1345-H1353 ◽  
Author(s):  
Jiafa Ren ◽  
Steven D. Crowley

The contributions of T lymphocytes to the pathogenesis of salt-sensitive hypertension has been well established. Under hypertensive stimuli, naive T cells develop into different subsets, including Th1, Th2, Th17, Treg, and cytotoxic CD8+ T cells, depending on the surrounding microenviroment in organs. Distinct subsets of T cells may play totally different roles in tissue damage and hypertension. The underlying mechanisms by which hypertensive stimuli activate naive T cells involve many events and different organs, such as neoantigen presentation by dendritic cells, high salt concentration, and the milieu of oxidative stress in the kidney and vasculature. Infiltrating and activated T subsets in injured organs, in turn, exert considerable impacts on tissue dysfunction, including sodium retention in the kidney, vascular stiffness, and remodeling in the vasculature. Therefore, a thorough knowledge of T-cell actions in hypertension may provide novel insights into the development of new therapeutic strategies for patients with hypertension.


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