Dahl-Iwai盐敏感大鼠高血压发展过程中脑和肾中的α2肾上腺素能受体

Alpha 2-adrenoceptors in brain and kidney during development of hypertension in Dahl-Iwai salt-sensitive rats.

作者信息

Tozawa M, Takishita S, Sunagawa O, Muratani H, Imai C, Kawazoe N, Fukiyama K

机构信息

Third Department of Internal Medicine, University of The Ryukyus, Okinawa, Japan.

出版信息

Clin Exp Hypertens. 1995 Aug;17(6):955-76. doi: 10.3109/10641969509033645.

DOI:10.3109/10641969509033645

PMID:7581263

Abstract

BACKGROUND

Both renal and extrarenal factors have been considered to contribute to the development of hypertension in Dahl salt-sensitive rats, but contents of both factors have not been established precisely.

AIM

To clarify the role of those factors in the sympathetic nervous system, we examined the regulation of alpha2-adrenoceptors in the lower brainstem and the renal tubular basolateral membranes simultaneously during the development of salt-induced hypertension in Dahl-Iwai salt-sensitive rats.

METHODS

Dahl-Iwai salt-sensitive or resistant rats were fed a high (8.0% NaCl)- or low (0.3%)- salt diet from 4 to 6 or 10 weeks of age. At 4, 6 and 10 weeks of age, the plasma membranes of the lower brainstem and the renal tubular basolateral membranes were obtained simultaneously and alpha 2-adrenoceptors were quantified by a radioligand binding assay using 3H-rauwolscine.

RESULTS

In the salt-sensitive rats, systolic blood pressure was significantly higher in those fed a high-salt diet than in those fed a low-salt diet. In the salt-resistant rats, both the high- and the low-salt groups showed similar blood pressure levels. At 6 weeks of age, alpha 2-receptor densities of the salt-sensitive rats fed a high-salt diet were lower in the lower brainstem and higher in the renal basolateral membranes than those fed a low-salt diet. In contrast, in the salt-resistant rats, both the high- and the low-salt groups had similar densities. At 10 weeks of age, the difference between the high- and the low-salt groups in the salt-sensitive rats disappeared in both the brainstem and the renal basolateral membranes.

CONCLUSIONS

Alpha 2-adrenoceptor regulation in the brainstem and the renal basolateral membranes differs between Dahl-Iwai salt-sensitive and salt-resistant rats. The modulation of alpha 2-adrenoceptors by a high salt intake may be essential particularly in the early phase of the development of salt-induced hypertension.

摘要

背景

肾性和肾外因素均被认为与 Dahl 盐敏感大鼠高血压的发生有关，但这两种因素的具体情况尚未明确。

目的

为阐明这些因素在交感神经系统中的作用，我们在 Dahl-Iwai 盐敏感大鼠盐诱导高血压的发展过程中，同时检测了低位脑干和肾小管基底外侧膜中α2-肾上腺素能受体的调节情况。

方法

将 Dahl-Iwai 盐敏感或抗性大鼠从 4 周龄至 6 周龄或 10 周龄分别给予高盐（8.0% NaCl）或低盐（0.3%）饮食。在 4 周、6 周和 10 周龄时，同时获取低位脑干和肾小管基底外侧膜的质膜，并用 3H-萝芙木碱通过放射性配体结合试验对α2-肾上腺素能受体进行定量。

结果

在盐敏感大鼠中，高盐饮食组的收缩压显著高于低盐饮食组。在盐抗性大鼠中，高盐和低盐组的血压水平相似。6 周龄时，高盐饮食的盐敏感大鼠低位脑干中的α2-受体密度低于低盐饮食组，而肾小管基底外侧膜中的α2-受体密度则高于低盐饮食组。相反，在盐抗性大鼠中，高盐和低盐组的密度相似。10 周龄时，盐敏感大鼠高盐和低盐组在脑干和肾小管基底外侧膜中的差异均消失。