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Regulatory mechanisms of renal hemodynamics at the basis of arteriolar level.

基于小动脉水平的肾血流动力学调节机制。

基本信息

批准号：
62570089
负责人：
ABE Youichi
金额：
$ 1.34万
依托单位：
Kagawa Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

Renal circulation are regulated by two resistance vessels, the afferent and the efferent arterioles. Different reactions of each arteriole to endogeneous and exogenous vasoactive agents regulate renal blood flow(RBF) and glomerular filtration rate(GFR). In the present research project, the in vivo and in vitro experiments were performed to determine the sites of action of adenosine(Ad), glucagon(Gl) and acetylcholine(ACh) and the nature of an afferent arteriole isolated from the canine kidney.1) in vivo experiments: At normal renal arterial pressure(RAP), RBF was increased by the above all agents. But, GFR was increased by Gl, decreased by Ad and unchanged by ACh. The increase in RBF by Gl occurred only at RAPs within the autoregulatory pressure range, and renal autoregulatory capability was attenuated. Contrary, Ad increased RBF at RAPs both within and below the autoregulatory pressure range, and the autoregulatory capability was not perceptibly impaired. ACh completely abolished the … More autoregulation of RBF. It is generally accepted that afferent arteriolar resistance attains a minimum value at RAP near the lower limit of the autoregulatory pressure range. Thus, these data indicate that Gl and Ad preferentially dilate the afferent arteriole and the efferent arteriole, respectively, and that ACh dilates both arterioles.2) in vitro experiments: The role of cyclic AMP(cAMP) as a second messenger of hormone or drug induced vasodilation has been proposed. A rise in intracellular cAMP concentration has been believed to be responsible for the relaxation of vascular smooth muscle by certain drugs. Then, the relationship between the dilation of isolated afferent arteriole and the cAMP accumulation induced by forskolin(Fo), a potent stimulator of adenylate cyclase. Fo(10^<-6> M) dilates the isolated afferent arteriole preconstructed with norepinephrine. Fo(10^<-5> M) produced 10-fold increase in cAMP production compared with control. Thus, the close relationship between the dilation of afferent arteriole and the cAMP accumulation. Less

肾循环是由两条阻力血管，传入和传出小动脉调节的。每个小动脉对内源性和外源性血管活性药物的不同反应调节肾血流量（RBF）和肾小球滤过率（GFR）。本研究通过体内和体外实验，确定了腺苷（Ad）、胰高血糖素（Gl）和乙酰胆碱（ACh）的作用部位和犬肾传入小动脉的性质。1)体内实验：在正常肾动脉压（RAP）下，上述药物均可使RBF升高。GFR在Gl作用下升高，Ad作用下降低，ACh作用下无明显变化。Gl增加RBF仅发生在自身调节压力范围内的RAPs，肾脏自身调节能力减弱。相反，在自调节压力范围内和低于自调节压力范围内，Ad增加了RAPs的RBF，并且自调节能力没有明显受损。ACh完全废除了RBF更多的自动调节。一般认为，传入小动脉阻力在RAP时达到最小值，接近自调节压力范围的下限。因此，这些数据表明Gl和Ad分别优先扩张传入小动脉和传出小动脉，而ACh扩张两个小动脉。2)体外实验：环AMP（cAMP）作为激素或药物诱导的血管舒张的第二信使的作用已经被提出。细胞内cAMP浓度的升高被认为是某些药物使血管平滑肌松弛的原因。然后，探讨了腺苷酸环化酶的强效刺激剂福斯克林（Fo）诱导离体传入小动脉扩张与cAMP积累的关系。Fo（10^<-6> M）使预构建去甲肾上腺素的离体传入小动脉扩张。与对照相比，Fo（10^<-5> M）的cAMP产量增加了10倍。因此，传入小动脉的扩张与cAMP的积累有密切的关系。少