scholarly journals Increased activity of the orexin system in the paraventricular nucleus contributes to salt-sensitive hypertension

2017 ◽  
Vol 313 (6) ◽  
pp. H1075-H1086 ◽  
Author(s):  
Michael J. Huber ◽  
Yuanyuan Fan ◽  
Enshe Jiang ◽  
Fengli Zhu ◽  
Robert A. Larson ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Paraventricular Nucleus ◽  
Mrna Levels ◽  
Nacl Solution ◽  
Sprague Dawley ◽  
Orexin A ◽  
Intracerebroventricular Infusion ◽  
Sd Rats ◽  
Salt Sensitive Hypertension ◽  
Increased Activity

The orexin system is involved in arginine vasopressin (AVP) regulation, and its overactivation has been implicated in hypertension. However, its role in salt-sensitive hypertension (SSHTN) is unknown. Here, we tested the hypothesis that hyperactivity of the orexin system in the paraventricular nucleus (PVN) contributes to SSHTN via enhancing AVP signaling. Eight-week-old male Dahl salt-sensitive (Dahl S) and age- and sex-matched Sprague-Dawley (SD) rats were placed on a high-salt (HS; 8% NaCl) or normal-salt (NS; 0.4% NaCl) diet for 4 wk. HS intake did not alter mean arterial pressure (MAP), PVN mRNA levels of orexin receptor 1 (OX1R), or OX2R but slightly increased PVN AVP mRNA expression in SD rats. HS diet induced significant increases in MAP and PVN mRNA levels of OX1R, OX2R, and AVP in Dahl S rats. Intracerebroventricular infusion of orexin A (0.2 nmol) dramatically increased AVP mRNA levels and immunoreactivity in the PVN of SD rats. Incubation of cultured hypothalamus neurons from newborn SD rats with orexin A increased AVP mRNA expression, which was attenuated by OX1R blockade. In addition, increased cerebrospinal fluid Na+ concentration through intracerebroventricular infusion of NaCl solution (4 µmol) increased PVN OX1R and AVP mRNA levels and immunoreactivity in SD rats. Furthermore, bilateral PVN microinjection of the OX1R antagonist SB-408124 resulted in a greater reduction in MAP in HS intake (−16 ± 5 mmHg) compared with NS-fed (−4 ± 4 mmHg) anesthetized Dahl S rats. These results suggest that elevated PVN OX1R activation may contribute to SSHTN by enhancing AVP signaling. NEW & NOTEWORTHY To our best knowledge, this study is the first to investigate the involvement of the orexin system in salt-sensitive hypertension. Our results suggest that the orexin system may contribute to the Dahl model of salt-sensitive hypertension by enhancing vasopressin signaling in the hypothalamic paraventricular nucleus.

Abstract P327: Increased Brain iNOS Contributes to Hypertension in Dahl Salt Sensitive Rats

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Michael J Huber ◽  
Fengli Zhu ◽  
Robert A Larson ◽  
Qing-Hui Chen ◽  
Zhiying Shan
Keyword(s):  
Hypertonic Saline ◽  
Neural Mechanism ◽  
Neuronal Cultures ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Inos Activity ◽  
Arterial Blood ◽  
Sd Rats ◽  
Inos Inhibitor ◽  
Salt Sensitive Hypertension

The hypothalamic paraventricular nucleus (PVN) is one of the key central nuclei to play an important role in regulating arterial blood pressure (ABP) of salt-sensitive hypertension (SSH). However, the detailed molecular mechanism(s) whereby the PVN increases ABP are not well understood. Here, we tested the hypothesis that high salt (HS) loading increases expression of iNOS in the PVN which contributes to SSH. Six-week-old male Dahl salt sensitive (Dahl S) rats and age matched Sprague Dawley (SD) rats were fed either a HS (4% NaCI) or a normal salt (NS, 0.4% NaCl) diet (n=4~7/group). Mean arterial pressure (MAP) was measured via tail cuff method. Five weeks following diet treatment, HS diet induced hypertension in Dahl S rats (HS: 153±9; vs. NS: 122±2 mmHg, P<0.05), but not in SD rats (HS: 107±3; vs. NS: 107±2 mmHg). Rats were then euthanized and PVN tissues were punched out for real time PCR. The HS diet induced dramatic increases in mRNA levels of iNOS (25-fold), and Fra1 (3.6-fold), a chronic neuronal activation marker, in Dahl S rat but not in SD rats. Next, we investigated the effect of intracerebroventricular (ICV) administration of hypertonic saline on PVN iNOS and Fra1 expression in SD rats. Anesthetized adult male SD rats received ICV infusion of isotonic NaCI (0.15 M, 2μl, as control) or hypertonic NaCI (2M, 2μl) (n=7~8/group). Three hours following ICV infusion, rats were euthanized and PVN mRNA levels of iNOS and Fra1 were assayed. ICV hypertonic saline increased mRNA levels of iNOS (9.5-fold) and Fra1 (4.1-fold). We further tested whether these increases in iNOS and Fra1 expression occurred in neurons. Incubation of hypertonic saline (10 mM NaCI) for 3 hours increased iNOS (6-fold) and Fra1 (2.8-fold) mRNA levels in neuronal cultures from the hypothalamus containing the PVN. Finally, we tested whether increased iNOS activity contributes to ABP elevation in Dahl SSH. In anaesthetized Dahl S rats, bilateral PVN microinjection of the iNOS inhibitor, aminoguanidine (250 pmol) significantly decreased MAP in HS treated animals compared to rats with a NS diet (HS: -13±3; vs. NS: -2±2 mmHg, P<0.05) (n=5/group). These observations suggest that HS intake increases iNOS expression in PVN neurons, which may contribute to the central neural mechanism of Dahl SSH.

scholarly journals Activation of the (pro)renin receptor in the paraventricular nucleus increases sympathetic outflow in anesthetized rats

2015 ◽  
Vol 309 (5) ◽  
pp. H880-H887 ◽  
Author(s):  
Michael J. Huber ◽  
Rupsa Basu ◽  
Cassie Cecchettini ◽  
Adolfo E. Cuadra ◽  
Qing-Hui Chen ◽  
...  
Keyword(s):  
Paraventricular Nucleus ◽  
Mrna Levels ◽  
Ros Production ◽  
Activator Protein 1 ◽  
Sprague Dawley ◽  
Neurogenic Hypertension ◽  
Napdh Oxidase ◽  
Arterial Blood ◽  
Sd Rats ◽  
Oxide Synthase

Previous studies have indicated that hyperactivity of brain prorenin receptors (PRR) is implicated in neurogenic hypertension. However, the role of brain PRR in regulating arterial blood pressure (ABP) is not well understood. Here, we test the hypothesis that PRR activation in the hypothalamic paraventricular nucleus (PVN) contributes to increased sympathetic nerve activity (SNA). In anaesthetized adult Sprague-Dawley (SD) rats, bilateral PVN microinjection of human prorenin (2 pmol/side) significantly increased splanchnic SNA (SSNA; 71 ± 15%, n = 7). Preinjection of either prorenin handle region peptide, the PRR binding blocker (PRRB), or tiron (2 nmol/side), the scavenger of reactive oxygen species (ROS), significantly attenuated the increase in SSNA (PRRB: 32 ± 5% vs. control, n = 6; tiron: 8 ± 10% vs. control, n = 5; P < 0.05) evoked by prorenin injection. We further investigated the effects of PRR activation on ROS production as well as downstream gene expression using cultured hypothalamus neurons from newborn SD rats. Incubation of brain neurons with human prorenin (100 nM) dramatically enhanced ROS production and induced a time-dependent increase in mRNA levels of inducible nitric oxide synthase (iNOS), NAPDH oxidase 2 subunit cybb, and FOS-like antigen 1 (fosl1), a marker for neuronal activation and a component of transcription factor activator protein-1 (AP-1). The maximum mRNA increase in these genes occurred 6 h following incubation (iNOS: 201-fold; cybb: 2 -fold; Ffosl1: 11-fold). The increases in iNOS and cybb mRNA were not attenuated by the AT1 receptor antagonist losartan but abolished by the AP-1 blocker curcumin. Our results suggest that PVN PRR activation induces sympathoexcitation possibly through stimulation of an ANG II-independent, ROS-AP-1-iNOS signaling pathway.

scholarly journals Differential Effects of Refeeding on Melanocortin-Responsive Neurons in the Hypothalamic Paraventricular Nucleus

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4329-4335 ◽  
Author(s):  
Edith Sánchez ◽  
Praful S. Singru ◽  
Runa Acharya ◽  
Monica Bodria ◽  
Csaba Fekete ◽  
...  
Keyword(s):  
Gene Expression ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Early Action ◽  
Sprague Dawley Rats ◽  
Melanocortin Signaling ◽  
Agouti Related Protein ◽  
Serum Tsh

To explore the effect of refeeding on recovery of TRH gene expression in the hypothalamic paraventricular nucleus (PVN) and its correlation with the feeding-related neuropeptides in the arcuate nucleus (ARC), c-fos immunoreactivity (IR) in the PVN and ARC 2 h after refeeding and hypothalamic TRH, neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels 4, 12, and 24 h after refeeding were studied in Sprague-Dawley rats subjected to prolonged fasting. Despite rapid reactivation of proopiomelanocortin neurons by refeeding as demonstrated by c-fos IR in ARC α-MSH-IR neurons and ventral parvocellular subdivision PVN neurons, c-fos IR was present in only 9.7 ± 1.1% hypophysiotropic TRH neurons. Serum TSH levels remained suppressed 4 and 12 h after the start of refeeding, returning to fed levels after 24 h. Fasting reduced TRH mRNA compared with fed animals, and similar to TSH, remained suppressed at 4 and 12 h after refeeding, returning toward normal at 24 h. AGRP and NPY gene expression in the ARC were markedly elevated in fasting rats, AGRP mRNA returning to baseline levels 12 h after refeeding and NPY mRNA remaining persistently elevated even at 24 h. These data raise the possibility that refeeding-induced activation of melanocortin signaling exerts differential actions on its target neurons in the PVN, an early action directed at neurons that may be involved in satiety, and a later action on hypophysiotropic TRH neurons involved in energy expenditure, potentially mediated by sustained elevations in AGRP and NPY. This response may be an important homeostatic mechanism to allow replenishment of depleted energy stores associated with fasting.

scholarly journals Letrozole-Induced Polycystic Ovary Syndrome Attenuates Cystathionine-β Synthase Gene Expression in the Ovaries of Female Sprague Dawley Rats

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1244-1244
Author(s):  
Amanda Bries ◽  
Joe Webb ◽  
Brooke Vogel ◽  
Claudia Carrillo ◽  
Aileen Keating ◽  
...  
Keyword(s):  
Gene Expression ◽  
Polycystic Ovary Syndrome ◽  
Mrna Expression ◽  
Polycystic Ovary ◽  
Elevated Serum ◽  
Reproductive Age ◽  
Sprague Dawley ◽  
Polycystic Ovaries ◽  
Ovary Syndrome ◽  
Sd Rats

Abstract Objectives Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects 10% of reproductive age women and leads to hyperandrogenism, abnormal menstrual cycles, and polycystic ovaries. Moreover, PCOS has been associated with elevated serum homocysteine; however, the characterization of one-carbon metabolism (OCM) in PCOS remains incomplete. The aim of our research was to examine OCM in a genetic and chemically-induced rodent model of PCOS: 1) viable yellow Agouti (Avy) mice; and 2) letrozole (Let)-induced Sprague Dawley (SD) rats. Methods Five wk old female Avy mice (N = 18), their lean controls (N = 18), and SD rats (N = 36) were acclimated for one wk. Following acclimation, the animals were placed on a modified standard AIN93G diet (energy, %: 50.4, carbohydrate; 17.3, protein; and 32.3, fat). Rats were randomly assigned to Let (1 g/kg BW) treatment or vehicle (carboxymethylcellulose) control that was administered via a subcutaneously implanted slow-release pellet every 30-d. For both models, 12 animals were randomly assigned to be euthanized during proestrus at one of the following ages: 8, 16 or 24 wk. Bodyweight and estrous cycles were measured daily. Ovaries were collected to assess gene expression of OCM. These data were analyzed using linear mixed models to determine the main effects of age and treatment at a significance level of P &lt; 0.05. Results Letrozole significantly reduced the occurrence of proestrus and estrus stages (P = 0.0001 and P = 0.006, respectively). Additionally, Let-induced rats had increased BW compared to control rats, across all age groups (P &lt; 0.0001). In contrast, Avy mice weighed less than their controls by 24 wk of age (P &lt; 0.0001). Cystathionine-β synthase (CBS) mRNA expression was downregulated in the Let-induced vs. control rats at 16 (59%; P &lt; 0.05) and 24 (77%; P &lt; 0.01) wk of age. As expected, Cyp19A1, aromatase mRNA was downregulated in the Let-induced rats (P = 0.02). Interestingly, betaine-homocysteine s-methyltransferase (BHMT) mRNA increased as a function of age in Let-induced rats (P = 0.03). Conclusions These data demonstrate that Letrozole-induced PCOS temporally decreases ovarian CBS mRNA expression; whereas, BHMT mRNA is upregulated as a function of age. Funding Sources This work was supported by the National Institute of Child Health and Human Development.

Effects of danshensu on the transforming growth factor-β1/smads signaling pathway in rats with lung injury

2020 ◽  
Vol 10 (11) ◽  
pp. 1816-1823
Author(s):  
Jing Qin ◽  
Xiaoqiang Zhang ◽  
Shengyan Wang ◽  
Yongming Zhang
Keyword(s):  
Lung Injury ◽  
Mrna Expression ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Abdominal Cavity ◽  
Physiological Saline ◽  
Transforming Growth Factor Β1 ◽  
Control Group ◽  
Sprague Dawley ◽  
Sd Rats

Observe the therapeutic effect of Danshensu on lung injury for rats, as well as explore the mechanism of Danshensu in TGF-β1/Smads signaling. Thirty Sprague-Dawley (SD) rats were intratracheally instilled with bleomycin to induce lung injury and interstitial fibrosis. Divided Thirty rats into three groups. DA group (η = 10): Inject 15 mg/kg Danshensu into the abdominal cavity; DXM group (η = 10): Inject 1 mg/kg dexamethasone into the abdominal cavity; BLM group (η = 10): Inject 2 mL physiological saline into the abdominal cavity. Then ten SD rats were intratracheally instilled with physiological saline as normal control group, NC group: Inject 2 mL physiological saline into the abdominal cavity. After a period of 28 days, the degree of pulmonary alveolitis was evaluated using hematoxylin-eosin (HE) staining, and the degree of lung fibrosis was evaluated using Masson?s trichrome (MT) staining. The immunohistochemistry was used to determine the expression of α-SMA. Magnetic nanoparticles+rtQ-PCR was used to determine the mRNA expressions for TGF-β1, Smad3, and Smad7. The alveolitis and pulmonary fibrosis in DA rats were obviously less than those in BLM rats and DXM rats. The expression of α-SMA in DA rats was obviously less than that of in BLM rats and DXM rats; the mRNA expression of TGF-β1 and Smad3 in DA rats were obviously reduced; the Smad7 mRNA expression was obviously up-regulated. DA can alleviate rat lung injury caused by bleomycin. Inhibiting the TGF-β1 and Smad3 mRNA expression, as well as boosting the Smad7 mRNA expression is one of the mechanisms by which Danshensu reduces lung injury.

Osmotically inactive skin Na+ storage in rats

2003 ◽  
Vol 285 (6) ◽  
pp. F1108-F1117 ◽  
Author(s):  
Jens Titze ◽  
Rainer Lang ◽  
Christoph Ilies ◽  
Karl H. Schwind ◽  
Karl A. Kirsch ◽  
...  
Keyword(s):  
Dry Weight ◽  
The Body ◽  
Sprague Dawley ◽  
Connective Tissues ◽  
Salt Diet ◽  
Sd Rats ◽  
Ovx Rats ◽  
Dry Ashing ◽  
Total Body ◽  
Salt Sensitive Hypertension

Compared with age-matched men, women are resistant to the hypertensive effects of dietary NaCl; however, after menopause, the incidence of salt-sensitive hypertension is similar in women and men. We recently suggested that osmotically inactive Na+ storage contributes to the development of salt-sensitive hypertension. The connective tissues, including those immediately below the skin that may serve as a reservoir for osmotically inactive Na+ storage, are affected by menopause. We tested the hypothesis that ovariectomy (OVX) might reduce osmotically inactive Na+ storage capacity in the body, particularly in the skin. Male, female-fertile, and female OVX Sprague-Dawley (SD) rats were fed a high (8%)- or low (0.1%)-NaCl diet. The groups received the diet for 4 or 8 wk. At the end of the experiment, subgroups received 0.9% saline infusion and urinary Na+ and K+ excretion was measured. Wet and dry weight (DW), water content in the body and skin, total body Na+ (rTBNa+) and skin Na+ (rSKNa+) content were measured relative to DW by desiccation and dry ashing. There were no gender differences in osmotically inactive Na+ storage in SD rats. All SD rats accumulated Na+ if fed 8% NaCl, but rTBNa+ was lower in OVX rats than in fertile rats on a low ( P < 0.001)- and a high ( P < 0.05)-salt diet. OVX decreased rSKNa+ ( P < 0.01) in the rats. A high-salt diet led to Na+ accumulation (ΔSKNa+) in the skin in all SD rats. Osmotically inactive skin Na+ accumulation was ∼66% of ΔSKNa+ in female and 82% in male-fertile rats, but there was no osmotically inactive Na+ accumulation in OVX rats fed 8% NaCl. We conclude that skin is an osmotically inactive Na+ reservoir that accumulates Na+ when dietary NaCl is excessive. OVX leads to an acquired reduction of osmotically inactive Na+ storage in SD rats that predisposes the rats to volume excess despite a reduced Na+ content relative to body weight.

scholarly journals Effects of tiletamine-xylazine-tramadol combination and its specific antagonist on AMPK in the brain of rats

2019 ◽  
Vol 63 (2) ◽  
pp. 285-292
Author(s):  
Ning Ma ◽  
Xin Li ◽  
Hong-bin Wang ◽  
Li Gao ◽  
Jian-hua Xiao
Keyword(s):  
Mrna Expression ◽  
Opposite Effect ◽  
Brain Regions ◽  
Control Group ◽  
Sprague Dawley ◽  
Sd Rats ◽  
The Central Nervous System ◽  
Specific Antagonist ◽  
Sedation And Analgesia ◽  
The Brain

AbstractIntroduction:Tiletamine-xylazine-tramadol (XFM) has few side effects and can provide good sedation and analgesia. Adenosine 5’-monophosphate-activated protein kinase (AMPK) can attenuate trigeminal neuralgia. The study aimed to investigate the effects of XFM and its specific antagonist on AMPK in different regions of the brain.Material and Methods:A model of XFM in the rat was established. A total of 72 Sprague Dawley (SD) rats were randomly divided into three equally sized groups: XFM anaesthesia (M group), antagonist (W group), and XFM with antagonist interactive groups (MW group). Eighteen SD rats were in the control group and were injected intraperitoneally with saline (C group). The rats were sacrificed and the cerebral cortex, cerebellum, hippocampus, thalamus, and brain stem were immediately separated, in order to detect AMPKα mRNA expression by quantitative PCR.Results:XFM was able to increase the mRNA expression of AMPKα1 and AMPKα2 in all brain regions, and the antagonist caused the opposite effect, although the effects of XFM could not be completely reversed in some areas.Conclusion:XFM can influence the expression of AMPK in the central nervous system of the rat, which can provide a reference for the future development of anaesthetics for animals.

Abstract 296: Norepinephrine Evoked Salt-Sensitive Hypertension Results in Impaired NCC Function, but Not Expression

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Kathryn Walsh ◽  
Sarah Mahne ◽  
Jill T Kuwabara ◽  
Richard D Wainford
Keyword(s):  
Salt Intake ◽  
Pcr Analysis ◽  
Kidney Cortex ◽  
Sprague Dawley ◽  
Sodium Homeostasis ◽  
Sd Rats ◽  
High Salt Intake ◽  
Induced Hypertension ◽  
Salt Sensitive Hypertension ◽  
The Impact

Aim: Recent controversial studies have proposed that excess norepinephrine (NE) evokes impaired NCC regulation to drive salt-sensitive hypertension. The following studies examine the impact of excess NE on salt-sensitivity and sodium homeostasis in conscious Sprague-Dawley (SD) rats. Methods: Naïve male SD rats, rats receiving a s.c. vehicle infusion (DMSO/Saline, 50:50), or rats receiving a s.c. NE infusion (600ng/min) were fed a 0.4% (NS) or 8% NaCl (HS) diet for 14 days. Additional rats received s.c. hydrochlorothiazide (HCTZ, 4mg/kg/d) in combination with NE (600ng/min) for 14 days on HS. On day 14, MAP, FENa, MAP response to i.v. hexamethonium (30mg/kg), and peak natriuresis to i.v. HCTZ (2mg/kg) infusion were assessed (N=4/gp). A PCR array examining NCC associated genes was performed on kidney cortex samples from each group. Results: NE increased MAP, FENa and vascular sympathetic tone (MAP [mmHg] NS 127±2, NE+NS 151±3, p<0.05). We observed no difference between the naïve and vehicle rats. A HS diet exacerbated NE induced hypertension (MAP [mmHg] HS 129±2, NE+HS 172±4, p<0.05), reduced FENa and prevented a salt stimulated reduction in HCTZ evoked natriuresis. Co-infusion of HCTZ with NE abolished the salt-sensitive component of NE-induced hypertension (MAP [mmHg] NE+HCTZ+HS: 152±3, p<0.05). PCR analysis revealed a significant increase in serine/threonine kinase 39 (0.83-fold increase vs. Naïve SD on NS) mRNA in NE+HS rats. We did not see NE or HS evoked changes in OSR-1, WNK4 or NCC mRNA in any group. Conclusion: The results support previous studies in mice and highlight an opposing interaction between excess NE and high salt intake on sodium homeostasis which exacerbated NE-induced hypertension via a mechanism independent of NE-mediated vascular constriction. Physiologically, our results show impaired NCC function, supporting previous data. In contrast, we failed to detect elevated NCC or WNK4 mRNA in response to NE infusion contradicting data generated in mice and suggesting a key role of altered NCC phosphorylation versus expression in NE treated rats.

scholarly journals Failure to upregulate the adenosine2A receptor-epoxyeicosatrienoic acid pathway contributes to the development of hypertension in Dahl salt-sensitive rats

2008 ◽  
Vol 295 (6) ◽  
pp. F1696-F1704 ◽  
Author(s):  
Elvira L. Liclican ◽  
John C. McGiff ◽  
John R. Falck ◽  
Mairéad A. Carroll
Keyword(s):  
Renal Perfusion ◽  
Epoxyeicosatrienoic Acid ◽  
Sprague Dawley ◽  
Salt Loading ◽  
Vasodilator Response ◽  
Sd Rats ◽  
Acid Pathway ◽  
Salt Sensitive Hypertension ◽  
Dose Dependent

Adenosine-activated renovascular dilatation in Sprague-Dawley (SD) rats is mediated by stimulating adenosine2A receptors (A2AR), which is linked to epoxyeicosatrienoic acid (EET) synthesis. The A2AR-EET pathway is upregulated by high salt (HS) intake in normotensive SD rats. Because this pathway is antipressor, we examined the role of the A2AR-EET pathway in Dahl salt-sensitive (SS) rats. Male Dahl salt-resistant (SR) and SS rats were fed either HS (8.0% NaCl) or normal salt (NS; 0.4% NaCl) diet for 7 days. On day 8, isolated kidneys were perfused with Krebs-Henseleit buffer containing indomethacin and NG-nitro-l-arginine methyl ester and preconstricted with phenylephrine. Bolus injections of the stable adenosine analog 2-chloroadenosine (2-CA; 0.1–20 μg) elicited dose-dependent dilation in both Dahl SR and SS rats. Dahl SR rats fed a HS diet demonstrated a greater renal vasodilator response to 10 μg of 2-CA, as measured by the reduction in renal perfusion pressure, than that of Dahl SR rats fed a NS diet (−104 ± 6 vs. −77 ± 7 mmHg, respectively; P < 0.05). In contrast, Dahl SS rats did not exhibit a difference in the vasodilator response to 2-CA whether fed NS or HS diet (96 ± 6 vs. 104 ± 13 mmHg in NS- and HS-fed rats, respectively). In Dahl SR but not Dahl SS rats, HS intake significantly increased purine flux, augmented the protein expression of A2AR and the cytochrome P-450 2C23 and 2C11 epoxygenases, and elevated the renal efflux of EETs. Thus the Dahl SR rat is able to respond to HS intake by recruiting EET formation, whereas the Dahl SS rat appears to have exhausted its ability to increase EET synthesis above the levels observed on NS intake, and this inability of Dahl SS rats to upregulate the A2AR-EET pathway in response to salt loading may contribute to the development of salt-sensitive hypertension.

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