Differential regulation of blood pressure and renal function by renal at1 receptors in normotensive and spontaneously hypertensive rats

2004 ◽  
Vol 17 (5) ◽  
pp. S95-S96
Author(s):  
M YONEDA
1991 ◽  
Vol 81 (1) ◽  
pp. 107-112 ◽  
Author(s):  
K. Fujito ◽  
M. Yokomatsu ◽  
N. Ishiguro ◽  
H. Numahata ◽  
Y. Tomino ◽  
...  

1. The purpose of this study was to determine the effect of dietary Ca2+ intake on blood pressure and erythrocyte Na+ transport in spontaneously hypertensive rats. 2. Spontaneously hypertensive rats and Wistar-Kyoto rats were fed diets with three different Ca2+ contents, 0.1% (low-Ca2+ diet), 0.6% (normal-Ca2+ diet) and 4.0% (high-Ca2+ diet), between 6 and 20 weeks of age. At 20 weeks of age, the levels of erythrocyte Na+ efflux, as well as Na+ and K+ contents in erythrocytes, were measured. 3. On the low-Ca2+ diet, spontaneously hypertensive rats showed an enhancement of hypertension. Conversely, on the high-Ca2+ diet, they showed an attenuation of the increase in blood pressure. Spontaneously hypertensive rats had a lower erythrocyte Na+ content and increased activity of the Na+ pump at higher levels of dietary Ca2+. Passive Na+ permeability and Na+-K+ co-transport were similar in spontaneously hypertensive rats on the low-, normal- and high-Ca2+ diets. There were no significant differences in blood pressure and in Na+ pump activity in WKY on the three different diets. 4. It is concluded that dietary Ca2+ might affect the regulation of blood pressure in spontaneously hypertensive rats by changing the activity of Na+ pump in the cell membrane.


1998 ◽  
Vol 76 (1) ◽  
pp. 63-67 ◽  
Author(s):  
María Reverte ◽  
Olga Flores ◽  
Belén Gallego ◽  
Antonio Lestón ◽  
José Miguel López-Novoa

We have studied during 30 days the effect of a low dose of NG-nitro-L-arginine methyl ester (1 mg ·kg-1 ·day-1 in drinking water) in the presence of D- or L-arginine (1 mg ·kg-1 ·day-1 in drinking water) in comparison with D- or L-arginine alone on blood pressure and renal function in conscious uninephrectomized female spontaneously hypertensive rats. At the end of the study, there was a significant increase in systolic blood pressure in the NG-nitro-L-arginine methyl ester + D-arginine group (307 ± 6 mmHg (1 mmHg = 133.3 Pa), n = 14, p << 0.05) in comparison with NG-nitro-L-arginine methyl ester + L-arginine (281 ± 6 mmHg, n = 14), L-arginine (262 ± 5 mmHg, n = 13), and D-arginine (258 ± 7 mmHg, n = 12) groups. There were no changes in diuresis, proteinuria, or sodium and potassium excretion between differently treated animals during this study. These results suggest that in uninephrectomized female spontaneously hypertensive rats, after 1 month blockade of NO synthesis with a low dose of NG-nitro-L-arginine methyl ester, vasculature is under tonic control by NO and it is not correlated with renal dysfunction.Key words: Key words: NG -nitro-L-arginine methyl ester (L-NAME), kidney, hypertension, spontaneously hypertensive rats, renaldysfunction, uninephrectomy.


1991 ◽  
Vol 260 (1) ◽  
pp. R21-R26 ◽  
Author(s):  
Y. Sato ◽  
K. Ando ◽  
E. Ogata ◽  
T. Fujita

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.


2014 ◽  
Vol 60 (01) ◽  
pp. 53-59
Author(s):  
Kalina Gjorgjievska ◽  
Dimce Zafirov ◽  
Maja Jurhar Pavlova ◽  
Svetlana Cekovska

The goal of this study was to compare the effects of valsartan and amlodipin on the systolic blood pressure and parameters specific to the renal function in salt loaded spontaneously hypertensive rats (SHR). 32 male SHR were used at age of 20 weeks and body weight ranging between 265-300 g. From 8 weeks of age tab water was replaced with a solution of NaCl (1%) given ad libitum. Rats were divided into 2 groups: valsartan treated group SHRVAL (n=16) in which valsartan was given at a dose of 10 mg/kg b. w. and amlodipine treated group SHRAMLO (n=16) in which amlodipine was given at a dose of 5 mg/kg b. w. For a period of 12 weeks we have evaluated the effect of the investigated drugs on systolic blood pressure, body weight and renal function tests. In salt loaded rats amlodipine was more effective in reducing the systolic blood pressure in contrast to valsartan who had more pronounced effect on renal parameters most evident in proteinuria. Since both treatment groups have different mechanism of action a combination therapy may be beneficial in improving renal function in SHR rats.


1999 ◽  
Vol 126 (8) ◽  
pp. 1769-1776 ◽  
Author(s):  
Costanza Emanueli ◽  
Julie Chao ◽  
Domenico Regoli ◽  
Lee Chao ◽  
Aiguo Ni ◽  
...  

Endocrinology ◽  
2006 ◽  
Vol 147 (7) ◽  
pp. 3539-3546 ◽  
Author(s):  
Walter Raasch ◽  
Christian Wittmershaus ◽  
Andreas Dendorfer ◽  
Inga Voges ◽  
Friedrich Pahlke ◽  
...  

Angiotensin II type 1 (AT1) receptors are expressed within organs of the hypothalamo-pituitary-adrenal (HPA) axis and seem to be important for its stress responsiveness. Secretion of CRH, ACTH, and corticosterone (CORT) is increased by stimulation of AT1 receptors. In the present study, we tested whether a blockade of the angiotensin II system attenuates the HPA axis reactivity in spontaneously hypertensive rats. Spontaneously hypertensive rats were treated with candesartan (2 mg/kg), ramipril (1 mg/kg), or mibefradil (12 mg/kg) for 5 wk. In addition to baseline levels, CORT and ACTH responses to injection of CRH (100 μg/kg) were monitored over 4 h. mRNA of CRH, proopiomelanocortin, AT1A, AT1B, and AT2 receptors was quantified by real-time PCR. All treatments induced equivalent reductions of blood pressure and had no effect on baseline levels of CORT and ACTH. However, both candesartan and ramipril significantly reduced CRH-stimulated plasma levels of ACTH (−26 and −15%) and CORT (−36 and −18%) and lowered hypothalamic CRH mRNA (−25 and −29%). Mibefradil did not affect any of these parameters. Gene expression of AT1A, AT1B, and AT2 receptors within the HPA axis was not altered by any drug. We show for the first time that antihypertensive treatment by inhibition of AT1 receptors or angiotensin-converting enzyme attenuates HPA axis reactivity independently of blood pressure reduction. This action is solely evident after CRH stimulation but not under baseline conditions. Both a reduced pituitary sensitivity to CRH and a down-regulation of hypothalamic CRH expression have the potential to reduce HPA axis activity during chronic AT1 blockade or angiotensin-converting enzyme inhibition.


2019 ◽  
Vol 9 (8) ◽  
pp. 1563-1567
Author(s):  
Zhigang Huang ◽  
Lin Shi ◽  
Ningling Sun

Objective: To investigate and statistically analyze homocysteine and folate on the regulation of blood pressure in spontaneously hypertensive rats (SHR), and explore whether the effect is related to angiotensin II type L receptor (AT1R) with bioinformatics. Methods: Eighteen SHRs were randomly divided into three groups: control group, methionine (Met) group and folate group (Met plus folate). Heart rate and blood pressure were monitored at different times. Serum Hcy levels were measured by ELISA kits. The expression of AT1R was detected by protein immunoblot. Results: Statistical analysis results indicated that mean arterial pressure (MAP) of the Met group at 4 and 6 weeks showed an increasing trend compared with the control group. And the Folate group at 4 weeks presented a decreasing trend compared with the Met group. The MAP of the other groups presented that great variation and no obvious trend. Serum Hcy levels were significantly increased in Met group, but decreased in folate group. AT1R protein were significantly decreased in Met and folate group. Conclusion: Hcy increased the MAP to a certain extent, and folic acid had a weak response to intervention to the effect. AT1R protein in renal tissue may not be a major effector in the pathway of elevated blood pressure.


1997 ◽  
Vol 25 (01) ◽  
pp. 21-26 ◽  
Author(s):  
Ho Sub Lee ◽  
Yun Cho Yu ◽  
Seong Tae Kim ◽  
Kyung Sik Kim

The aim of this study was to investigate the effects of moxibustion at the meridian points BL-15 (Xin-shu) and BL-27 (Xiao-chang-shu) on renal function, systolic blood pressure, plasma levels of renin activity, aldosterone and atrial natriuretic peptide in spontaneously hypertensive rats. The results showed that urine volume increased significantly after moxibustion at the meridian points BL-15, but decreased at BL-27. Urinary excretion of Na + decreased after moxibustion at the meridian points BL-15 and BL-27. Systolic blood pressure decreased after moxibustion at the meridian point BL-15. No effect was observed at BL-27. Plasma levels of aldosterone and renin activity increased significantly, but the levels of atrial natriuretic peptide decreased significantly after moxibustion at BL-15. Plasma levels of aldosterone and atrial natriuretic peptide increased significantly after moxibustion at the meridian points BL-27. These results suggest that the meridian points BL-15 and BL-27 are related to the regulation of renal function and the secretion of hormone with body fluid metabolism.


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