Abstract P213: Furosemide-mediated Suppression Of P 38 MAPK Signaling Abrogates Cholinergic-mediated Salt Sensitive Hypertension In Young Spontaneously Hypertensive Rats

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Nandita Raikwar ◽  
Trever Maiers ◽  
Holly Hohmann ◽  
Alan Ryan ◽  
Peter Snyder ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Nicotinic Acetylcholine Receptors ◽  
Spontaneously Hypertensive Rats ◽  
Receptor Activation ◽  
Mapk Signaling ◽  
Hypertensive Rats ◽  
Inflammatory Pathway ◽  
Spontaneously Hypertensive ◽  
Fractional Excretion Of Sodium ◽  
Salt Sensitive Hypertension

Hypertension is a major cause of premature death worldwide. Inflammatory macrophages play a key role in the pathogenesis of hypertension. Our lab has observed that nicotinic acetylcholine receptors (nAChR) activation potentiates salt-sensitive hypertension in Spontaneously Hypertensive Rats (SHR). Cholinergic receptor activation causes infiltration of CD68 + macrophages into the renal cortex/medulla junction and results in enhanced expression of renal sodium-potassium chloride cotransporter (NKCC2). To determine whether or not NKCC2 plays a role in the activation of inflammatory pathway furosemide, a selective pharmacologic blocker of NKCC2, was used to block NKCC2 expression in SHR in current study. Young pre-hypertensive SHR, receiving nicotine infusion (15mg/kg/day), were fed HSD (4% NaCl) and treated with either saline or furosemide (20mg/kg/day) intraperitoneal injections. There was a 16% increase (158.5±7.3 mmHg to 183.6±7.0 mmHg) in the systolic blood pressure in SHR that received saline injections, compared to no increase in SHR that received furosemide (155±6.0 mmHg to 148±3.6 mmHg) (p<0.0016). There was over a two-fold increase in fractional excretion of sodium (FENa, p=0.03) in the furosemide group, compared to saline controls. Although furosemide injections did not alter renal NKCC2 expression, there was nearly 50% reduction in phosphorylated p38 MAPK (p=0.0002) and a 25% decrease in renal infiltration of inflammatory CD68 + macrophages in SHR receiving furosemide injections, compared to saline controls. Interestingly, there was also a significant reduction in urinary albumin in response to furosemide injections (14.7±5.7 control vs 3.3±0.9 furosemide, p=0.027). Based on these findings, we conclude that furosemide results in cessation of the development of hypertension via interruption of a p38-MAPK dependent inflammatory pathway.

scholarly journals Increased Blood Pressure Causes Lymphatic Endothelial Dysfunction via Oxidative Stress in Spontaneously Hypertensive Rats

Hypertension ◽  
2020 ◽  
Vol 76 (2) ◽  
pp. 598-606
Author(s):  
Masashi Mukohda ◽  
Risuke Mizuno ◽  
Hiroshi Ozaki
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Blood Pressure ◽  
Endothelial Dysfunction ◽  
Nadph Oxidase ◽  
Sodium Nitroprusside ◽  
P38 Mapk ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive

The lymphatic system is involved in the pathogenesis of edema, inflammation, and cancer metastasis. Because lymph vessels control fluid electrolytes and volume balance, changes in lymphatic activity can be expected to alter systemic blood pressure. This study examined possible changes in lymphatic contractile properties in spontaneously hypertensive rats (SHR). Thoracic ducts isolated from 10- to 12-week-old SHR exhibited either decreased acetylcholine-induced endothelium-dependent relaxation or sodium nitroprusside-induced endothelium-independent relaxation compared with age-matched Wister-Kyoto rats. The impairment in acetylcholine responsiveness was more pronounced than sodium nitroprusside responsiveness. N-Nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor blunted acetylcholine-induced relaxation in Wister-Kyoto rats, indicating an involvement of endothelial nitric oxide production. Endothelial dysfunction in lymph vessels of SHR was attenuated by tempol (a superoxide dismutase mimetic), apocynin, or VAS-2870 (NADPH oxidase inhibitors). Consistent with these observations, nitrotyrosine levels were significantly elevated in SHR, indicative of increased oxidative stress. In addition, protein expression of NADPH oxidase 2 and phosphorylation of p47 phox (Ser345) were significantly increased in SHR. Further, SB203580 (a p38 MAPK inhibitor) restored the acetylcholine-induced relaxation in SHR. It is notable that 4-week-old SHR, which exhibited normal blood pressure, did not show any decreased activity of acetylcholine- or sodium nitroprusside-induced relaxation. Additionally, antihypertensive treatment of 4-week-old SHR with hydrochlorothiazide and reserpine or hydrochlorothiazide and hydralazine for 6 weeks completely restored lymphatic endothelial dysfunction. We conclude that contractile activity of lymphatic vessels is functionally impaired with the development of increasing blood pressure, which is mediated through increased oxidative stress via the p38 MAPK/NADPH oxidase 2 pathway.

Renal interstitial hydrostatic pressure during pressure natriuresis in hypertension

1988 ◽  
Vol 255 (5) ◽  
pp. R756-R759 ◽  
Author(s):  
A. A. Khraibi ◽  
F. G. Knox
Keyword(s):  
Hydrostatic Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Left Kidney ◽  
Hypertensive Rats ◽  
Polyethylene Matrix ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto Rats ◽  
Fractional Excretion Of Sodium ◽  
Wistar Kyoto ◽  
Pressure Natriuresis

The objective of this study was to test the hypothesis that changes in renal perfusion pressure (RPP) are not fully transmitted to the renal interstitium in spontaneous hypertension in comparison with normotensive states. Okamoto spontaneously hypertensive and normotensive Wistar-Kyoto rats were used in this study. Renal interstitial hydrostatic pressure (RIHP) was measured directly and continuously via a polyethylene matrix that was implanted chronically in the left kidney 3 wk before RIHP measurement. When RPP was allowed to increase from 136 +/- 0.5 to 162 +/- 1.3 mmHg in male spontaneously hypertensive rats, RIHP was not significantly changed from 3.7 +/- 0.9 to 4.6 +/- 1.1 mmHg, and fractional excretion of sodium (FENa) increased significantly from 0.26 +/- 0.12 to 0.65 +/- 0.15% (P less than 0.05). When RPP was allowed to change from 104 +/- 0.9 to 127 +/- 1.3 mmHg in male Wistar-Kyoto rats, RIHP increased markedly from 4.0 +/- 0.3 to 7.2 +/- 0.4 mmHg (P less than 0.05), and FENa was significantly elevated from 0.27 +/- 0.08 to 2.02 +/- 0.55% (P less than 0.05). In conclusion, spontaneously hypertensive rats have a blunted increase in RIHP and pressure natriuresis response in comparison with Wistar-Kyoto rats. Thus, in Okamoto spontaneously hypertensive rats, the effect of RPP on RIHP is attenuated, leading to a blunted pressure natriuresis response.

scholarly journals Involvement of complement 3 in the salt-sensitive hypertension by activation of renal renin-angiotensin system in spontaneously hypertensive rats

2018 ◽  
Vol 315 (6) ◽  
pp. F1747-F1758 ◽  
Author(s):  
Eriko Negishi ◽  
Noboru Fukuda ◽  
Tomoyasu Otsuki ◽  
Mayumi Katakawa ◽  
Kazutoshi Komatsu ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Renin Angiotensin System ◽  
Hypertensive Rats ◽  
Angiotensin System ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Complement 3 ◽  
Salt Sensitive Hypertension ◽  
E Cadherin

We previously showed that complement 3 (C3) is highly expressed in mesenchymal tissues in spontaneously hypertensive rats (SHR). We targeted C3 gene by zinc-finger nuclease (ZFN) gene-editing technology and investigated blood pressure and phenotype in SHR. Blood pressure was measured by tail-cuff and telemetry methods. Histology and expression of liver X receptor α (LXRα), renin, Krüppel-like factor 5 (KLF5), and E-cadherin were evaluated in kidneys. Mesangial cells (MCs) were removed from glomeruli from three strains, and we evaluated the phenotype in vitro. SHR showed the salt-sensitive hypertension that was abolished in C3 knockout (KO) SHR. Proliferation of MCs from SHR was higher than that from Wistar-Kyoto (WKY) rats and showed a synthetic phenotype. Renal injury scores were higher in SHR than in WKY rats and C3 KO SHR. Expression of E-cadherin was lower, and expression of renin was higher in the nephrotubulus from SHR than WKY rats and C3 KO SHR. Expression of C3 α-chain protein and α-smooth muscle actin protein was significantly higher in renal medulla from SHR than from WKY rats. Expression of angiotensinogen, LXRα, renin, and KLF5 mRNA was increased in kidney from SHR compared with C3 KO SHR. Intrarenal angiotensin II levels were significantly higher in kidney from SHR than WKY rats and C3 KO SHR. Urinary epinephrine and norepinephrine excretions were significantly higher in SHR than in WKY rats and C3 KO SHR. These findings showed that increased C3 induces salt-sensitive hypertension with increases in urinary catecholamine excretion and intrarenal activation of the renin-angiotensin system by the dedifferentiation of mesenchymal tissues in kidney from SHR.

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