StAR expression and the long-term aldosterone response to high-potassium diet in Wistar-Kyoto and spontaneously hypertensive rats

2007 ◽  
Vol 292 (1) ◽  
pp. E16-E23 ◽  
Author(s):  
Barbara Peters ◽  
Philipp Teubner ◽  
Susanne Clausmeyer ◽  
Tanja Puschner ◽  
Christiane Maser-Gluth ◽  
...  
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Regulatory Protein ◽  
Mrna Levels ◽  
Ang Ii ◽  
Hypertensive Rats ◽  
High Potassium ◽  
Spontaneously Hypertensive ◽  
Aldosterone Production ◽  
Wistar Kyoto

ANG II and potassium are known to increase steroidogenic acute regulatory protein (StAR) levels. However, a corresponding increase in StAR mRNA levels has so far been observed only in response to ANG II. We therefore studied the regulation of adrenal StAR mRNA expression in the context of dietary potassium-stimulated aldosterone production. Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were fed a diet containing either 1 or 4% KCl for 5 days. The high-potassium diet increased StAR mRNA levels within the zona glomerulosa in both strains, as demonstrated by in situ hybridization. However, aldosterone production increased in WKY but not in SHR (WKY: from 22.8 ± 4.8 to 137 ± 25 ng/100 ml, P < 0.001, vs. SHR: from 29 ± 3.8 to 51 ± 10.2 ng/100 ml, not significant). This increase was associated with an increase in Cyp11b2 mRNA levels in WKY (3-fold; P < 0.001) but not in SHR. In both strains, the 4% KCl diet was associated with increased plasma renin-independent aldosterone production, as indicated by the marked increase of the aldosterone-to-renin ratios (from 1.4 ± 0.3 to 9 ± 3 in WKY and from 3 ± 1 to 14 ± 5 in SHR; P < 0.002). We conclude that an increase of StAR mRNA levels within the outer cortex is involved in the long-term adrenal response to potassium. This increase alone is not sufficient to increase aldosterone production in the presence of normal Cyp11b2 mRNA levels.

High-potassium diet attenuates salt-induced acceleration of hypertension in SHR

1991 ◽  
Vol 260 (1) ◽  
pp. R21-R26 ◽  
Author(s):  
Y. Sato ◽  
K. Ando ◽  
E. Ogata ◽  
T. Fujita
Keyword(s):  
Blood Pressure ◽  
Renal Function ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
High Potassium ◽  
Spontaneously Hypertensive ◽  
Antihypertensive Action ◽  
High K ◽  
Wistar Kyoto ◽  
Renal Vascular

We studied the effects of K supplementation (8% KCl) for 4 wk on blood pressure (BP), Na space, and renal hemodynamics in 5-wk-old, spontaneously hypertensive rats (SHR) or age-matched Wistar-Kyoto rats (WKY) eating normal-NaCl (0.66%) or high-NaCl (8%) diet. In WKY, high-Na and/or high-K diets had no effects on BP. In SHR, Na load accelerated the development of hypertension, whereas K supplementation did not affect BP of normal-Na SHR but attenuated the increase in BP with Na load. Correspondingly, Na load in SHR significantly increased renal vascular resistance (RVR), and K supplementation attenuated the increased RVR of Na-loaded SHR. Moreover, Na space of SHR was increased compared with that of WKY, and although Na load did not affect Na space, K supplementation tended to decrease Na space in SHR. These results indicate that 9-wk-old SHR is relatively volume-expanded compared with age-matched WKY, and K supplementation could improve the lowered slope of the pressure-Na excretion relationship in SHR, resulting in maintenance of Na balance. Thus the data suggest that changes in RVR, which might be intimately related to renal function for Na excretion, contribute to both salt sensitivity of SHR and antihypertensive action of K supplementation in Na-loaded SHR.

scholarly journals Perindoprilat Changes ANG (1-9) Production in Renal Arteries Isolated From Young Spontaneously Hypertensive Rats After ANG I Incubation

2016 ◽  
pp. 561-570
Author(s):  
P. P. WOŁKOW ◽  
B. BUJAK-GIŻYCKA ◽  
J. JAWIEŃ ◽  
R. OLSZANECKI ◽  
J. MADEJ ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Renal Artery ◽  
Spontaneously Hypertensive Rats ◽  
Renal Arteries ◽  
Ang Ii ◽  
Shr Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Old Rats ◽  
Wistar Kyoto

We used mass spectrometry to quantitate production of angiotensinogen metabolites in renal artery of 3- and 7-month-old Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR). Tissue fragments were incubated for 15 min in oxygenated buffer, with added angiotensin I. Concentrations of angiotensins I (ANG I), II (ANG II), III (ANG III), IV (ANG IV), angiotensin (1-9) [ANG (1-9)], angiotensin (1-7) [ANG (1-7)], and angiotensin (1-5) [ANG (1-5)], excreted into the buffer during experiment, were measured using liquid chromatography-mass spectrometry (LC/MS) and expressed per mg of dry tissue. Effects of pretreatment with 10 μM perindoprilat on the production of ANG I metabolites were quantitated. Background production of any of ANG I metabolites differed neither between WKY and SHR rats nor between 3- and 7-month-old rats. Perindoprilat pretreatment of renal arteries resulted, as expected, in decrease of ANG II production. However, renal arteries of 7-month-old SHR rats were resistant to ACE inhibitor and did not change ANG II production in response to perindoprilat. In renal arteries, taken from 3-month-old rats, pretreated with perindoprilat, incubation with ANG I, resulted in the level of ANG (1-9) significantly higher in SHR than WKY rats. Our conclusion is that in SHR rats, sensitivity of renal artery ACE to perindoprilat inhibition changes with age.

Modification of mesangial cell function by chloride is attenuated in spontaneously hypertensive rats

1994 ◽  
Vol 266 (4) ◽  
pp. F586-F591 ◽  
Author(s):  
T. Okuda ◽  
Y. Inishi ◽  
T. Arakawa ◽  
M. Ohara ◽  
K. Kurokawa
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Cell Function ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Pge2 Production ◽  
Ang Ii ◽  
Hypertensive Rats ◽  
Cell Contraction ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

The effects of extracellular Cl- concentration ([Cl-]o) on cultured mesangial cells from spontaneously hypertensive rats (SHR) were examined. Angiotensin II (ANG II)- and vasopressin (VP)-induced cell contraction and Ca2+ transients of SHR mesangial cells were unaffected when the cells were preincubated with 10 mM [Cl-]o, while obvious suppression of the responses to these agents was observed in Wistar-Kyoto (WKY) mesangial cells. Enhanced prostaglandin E2 (PGE2) production was elicited by a decrease in [Cl-]o in WKY mesangial cells. In contrast, PGE2 synthesis by SHR mesangial cells was not enhanced by low [Cl-]o. However, ANG II-stimulated PGE2 production and the attenuation of ANG II-induced cell contraction and Ca2+ transients by the addition of exogenous PGE2 were present equally in both WKY and SHR mesangial cells. Based on these findings, we conclude that the absence of modification of mesangial cell function by [Cl-]o in SHR is due to the inability of low [Cl-]o to enhance PGE2 production. Insensitivity of SHR mesangial cells to changes in [Cl-]o might underlie the dysregulation of renal function in SHR.

Altered muscle metabolism associated with vasoconstriction in spontaneously hypertensive rats

1998 ◽  
Vol 275 (6) ◽  
pp. E1007-E1015 ◽  
Author(s):  
Ji-Ming Ye ◽  
Eric Q. Colquhoun
Keyword(s):  
Glucose Uptake ◽  
Spontaneously Hypertensive Rats ◽  
Perfusion Pressure ◽  
Lactate Production ◽  
Ang Ii ◽  
Hypertensive Rats ◽  
Response Curves ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

In the rat muscle vascular bed, vasoconstrictors either increase or decrease oxygen consumption (V˙o 2). The present study compared the effects of norepinephrine (NE), angiotensin II (ANG II), and 5-hydroxytryptamine (5-HT) on vasoconstriction-associated metabolism in the constant-flow perfused hindlimb of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) in the absence of insulin. Basal perfusion pressure,V˙o 2, glucose uptake, and lactate production were increased by 21.4, 11.9, 46.4, and 44.9% ( P < 0.05 for all), respectively, in SHR, which also had higher blood pressure and metabolic rate ( P < 0.05) in vivo. Dose-response curves for NE-induced perfusion pressure,V˙o 2, and lactate production in SHR were shifted to the left compared with WKY. Associated with the increased perfusion pressure, NE-inducedV˙o 2 and glucose uptake were both decreased ( P < 0.01), particularly at high concentrations. These differences were unaffected by 10 μM propranolol but were all diminished by further addition of prazosin (2.5 nM). ANG II stimulatedV˙o 2, glucose uptake, and lactate production in both strains, but the increased lactate production was smaller in SHR ( P < 0.05) with a proportional decrease ( P< 0.05) in glucose uptake. Conversely, 5-HT decreasedV˙o 2 in both strains ( P < 0.01), and this effect was greater in SHR ( P < 0.01). These data suggest that SHR muscle thermogenesis and glucose uptake are impaired during vasoconstriction, especially in response to NE.

scholarly journals Ganglionic Long-Term Potentiation in Prehypertensive and Hypertensive Stages of Spontaneously Hypertensive Rats Depends on GABA Modulation

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Luis A. Martínez ◽  
Fredy Cifuentes ◽  
Miguel A. Morales
Keyword(s):  
Synaptic Plasticity ◽  
Spontaneously Hypertensive Rats ◽  
Long Term Potentiation ◽  
Hypertensive Rats ◽  
Gaba A ◽  
Spontaneously Hypertensive ◽  
Term Potentiation ◽  
Cervical Ganglia ◽  
Wistar Kyoto

The sympathetic nervous system (SNS) regulates body functions in normal and pathological conditions and is characterized by the presence of a neuroplastic phenomenon, termed ganglionic long-term potentiation (gLTP). In hypertension, either in spontaneously hypertensive rats (SHR) or in humans, sympathetic hyperfunction, such as elevated SNS outflow and changes in synaptic plasticity have been described. Because enhanced SNS outflow is detected in the hypertensive stage and, more importantly, in the prehypertensive phase of SHR, here we explored whether synaptic plasticity, particularly gLTP, was modified in the superior cervical ganglia (SCG) of prehypertensive SHR. Furthermore, considering that GABA modulates sympathetic synaptic transmission and gLTP in Wistar rats, we studied whether GABA might modulate gLTP expression in SHR. We characterized gLTP in the SCG of young prehypertensive 6-week-old (wo) and adult hypertensive (12 wo) SHR and in the SCG of Wistar Kyoto (WKy) normotensive control rats of the same ages. We found that gLTP was expressed in 6 wo SHR, but not in 12 wo rats. By contrast, in WKy, gLTP was expressed in 12 wo, but not in 6 wo rats. We also found that gLTP depends on GABA modulation, as blockade of GABA-A subtype receptors with its antagonist bicuculline unmasked gLTP expression in adult SHR and young WKy. We propose that (1) activity-dependent changes in synaptic efficacy are altered not only during hypertension but also before its onset and (2) GABA may play a modulatory role in the changes in synaptic plasticity in SHR, because the blockade of GABA-A receptors unmasked the expression of gLTP. These early changes in neuroplasticity and GABA modulation of gLTP could be part of the sympathetic hyperfunction observed in hypertension.

scholarly journals Proteomic identification of the proteins related to cigarette smoke-induced cardiac hypertrophy in spontaneously hypertensive rats

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuki Kitamura ◽  
Nathan Mise ◽  
Yurie Mori ◽  
Yuka Suzuki ◽  
Tomoki Ohashi ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Cigarette Smoke ◽  
Spontaneously Hypertensive Rats ◽  
High Dose ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Difference Gel Electrophoresis ◽  
Wistar Kyoto ◽  
Shock Proteins

Abstract Smoking increases the risk of cardiovascular diseases. The present study was designed to determine the effects of 2-month exposure to cigarette smoke (CS) on proteins in the left ventricles of spontaneously hypertensive rats (SHR) and to identify the molecular targets associated with the pathogenesis/progression of CS-induced cardiac hypertrophy. SHR and Wistar Kyoto rats (WKY) were exposed to CS at low (2 puffs/min for 40 min) or high dose (2 puffs/min for 120 min), 5 days a week for 2 months. Using the two-dimensional fluorescence difference gel electrophoresis combined with MALDI-TOF/TOF tandem mass spectrometry, we compared differences in the expression levels of proteins in the whole left ventricles induced by long-term smoking. High-dose CS mainly caused cardiac hypertrophy in SHR, but not WKY, but no change in blood pressure. Proteomic analysis identified 30 protein spots with significant alterations, with 14 up-regulated and 16 down-regulated proteins in the left ventricles of CS-exposed SHR, compared with control SHR. Among these proteins, two members of the heat shock proteins (HSP70 and HSP20) showed significant up-regulation in the left ventricles of CS high-dose SHR, and the results were confirmed by western blot analysis. Our findings suggested that HSPs play an important role in regulation of CS-induced cardiac hypertrophy.

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