Assessment of intrarenal blood flow distribution and sodium excretion using contrast ultrasonography

肾内血流分布在调节各种肾功能（如尿浓度和钠排泄）中的重要性已得到充分认识。然而，目前还没有可靠的方法来测量体内肾脏的局部血流。我们利用对比超声结合5%超声白蛋白在杂种狗的主动脉内注射，研究了局部肾血流量与体内钠排泄的相关性。5%白蛋白超声浓度0.15 ~ 0.25ml/kg对肾实质超声增强效果满意。此外，在肾内乙酰胆碱输注期间，内/外肾皮质峰值强度比显著增加。低剂量静脉输注一氧化氮（NO）合成抑制剂N^ g -硝基- l -精氨酸甲酯（L-NAME）可显著抑制等渗生理盐水细胞外扩张的利钠反应，但不改变肾总血浆流量和肾皮质血流分布。L-NAME的这种抑制作用被血管紧张素II受体（AT_1）拮抗剂L-158,809预处理完全消除，这表明在NO合成抑制期间，血管紧张素II对急性细胞外体积扩张的肾脏排泄反应的降低依赖于血管紧张素II。此外，我们通过静脉注射由半乳糖/棕榈酸组成的造影剂，在肾脏血管或实质疾病患者的彩色多普勒血流显像中获得了有效的信号增强。因此，这些结果表明，局部肾血流量和钠排泄之间的相关性可以通过对人类信号增强的定量分析来检测。

The importance of the distribution of intrarenal blood flow in the regulation of various renal functions, such as urine concentration and sodium excretion, has been well recognized. However, there have been no reliable methods to measure local blood flow in the kidney in vivo. We studied the correlations between regional renal Blood flow and sodium excretion in vivo using contrast ultrasonograpy combined with intraaortic injection of a sonicated 5% albumin in mongrel dogs. Satisfactory sonographic enhancement in renal parenchyma was obtained by the sonicated 5% albumin of 0.15-0.25ml/kg. Furthermore, the inner/outer renal cortex ratio of peak intensity significantly increased during the intrarenal acetylcholine infusion. Intravenous infusion of nitric oxide (NO) synthesis inhibitor, N^G-nitro-L-arginine methyl ester (L-NAME), at a low dose significantly inhibited the natriuretic response to acte extracellular volume expansion with isotonic saline without altering total renal plasma flow and the distribution of renal cortical blood flow. This inhibitory effect of L-NAME was completely abolished by the pretreatment with angiotensin II receptor (AT_1) antagonist, L-158,809, suggesting an angiotensin II dependency of the reduced renal excretory response to acute extracellular volume expansion during NO synthesis inhibition.In addition, we obtained effective signal enhancement in color Doppler flow imaging in the kidney with an intravenous injection of the contrast agent consisting of galactose/palmitic acid in patients with renal vascular or parenchymal diseases. Thus, these results suggest that the correlations between regional renal blood flow and sodium excretion can be detected by a quantitative analysis of signal enhancement in humans.