Amiri F, Garcia R
Laboratory of Experimental Hypertension and Vasoactive Peptides, Clinical Research Institute of Montreal, Quebec, Canada.
Am J Physiol. 1996 May;270(5 Pt 1):E810-5. doi: 10.1152/ajpendo.1996.270.5.E810.
The activity of the renin-angiotensin system (RAS) can be influenced by sodium intake and angiotensin II (ANG II) infusion. It has been shown that ANG II can regulate the density of its receptors. Therefore, we investigated the regulation of glomerular and preglomerular vascular ANG II receptors by changes in RAS activity. Sprague-Dawley rats were fed a low- or high-sodium diet or were infused with nonpressor or pressor doses of ANG II for 7 days. ANG II receptor characteristics were determined by radioligand binding assays with use of ANG II antagonists losartan and PD-123319. AT1 was the only receptor type found in membrane preparations from all groups. Glomerular ANG II receptor characteristics in all groups were unchanged compared with their controls, whereas vascular receptor density was significantly downregulated by sodium restriction. We conclude that glomerular and preglomerular vascular ANG II receptors are differentially regulated such that AT1 receptors in preglomerular vessels can be regulated by changes in endogenous RAS. ANG II infusion did not induce any modification of either glomerular or vascular AT1 receptors, suggesting a predominant role of the endogenous local renal RAS.
肾素-血管紧张素系统（RAS）的活性可受钠摄入量和血管紧张素II（ANG II）输注的影响。研究表明，ANG II可调节其受体的密度。因此，我们研究了RAS活性变化对肾小球和球前血管ANG II受体的调节作用。将Sprague-Dawley大鼠喂食低钠或高钠饮食，或输注非升压或升压剂量的ANG II，持续7天。使用ANG II拮抗剂氯沙坦和PD-123319，通过放射性配体结合试验测定ANG II受体特征。AT1是所有组膜制剂中发现的唯一受体类型。与对照组相比，所有组的肾小球ANG II受体特征均未改变，而血管受体密度因钠限制而显著下调。我们得出结论，肾小球和球前血管ANG II受体受到不同调节，使得球前血管中的AT1受体可受内源性RAS变化的调节。ANG II输注未引起肾小球或血管AT1受体的任何改变，提示内源性局部肾RAS起主要作用。
