兔急性肾动脉狭窄对肾脏组织弹性的影响

Impact of acute renal artery stenosis on tissue elasticity of the kidney: an animal study

目的研究不同程度急性肾动脉狭窄对肾皮质、肾锥体及肾窦的超声弹性模量值的影响。方法 10只日本大耳白兔,麻醉、开腹、分离左肾动脉,用束扎法造成不同程度肾动脉狭窄后,分为3组:肾动脉狭窄0%组(10只)、肾动脉狭窄≥50%组(9只)及肾动脉狭窄100%组(8只)。采用超声剪切波弹性成像技术检测左肾中部肾皮质、肾锥体及肾窦的杨氏模量平均值,比较不同程度肾动脉狭窄时左肾组织硬度变化。在上述3种程度肾动脉狭窄超声剪切波弹性模量值测量后,各取1个肾脏进行病理学研究。结果肾动脉狭窄0%组,左肾中部肾皮质、肾锥体及肾窦的杨氏模量值分别为(16.31±1.70)k Pa、(13.38±1.63)k Pa、(12.75±2.26)k Pa;肾动脉狭窄≥50%组,左肾中部肾皮质、肾锥体及肾窦的杨氏模量值分别为(14.16±2.34)k Pa、(11.49±2.70)k Pa及(10.72±2.56)k Pa;肾动脉狭窄100%组,左肾中部肾皮质、肾锥体及肾窦的杨氏模量值分别为(11.35±1.48)k Pa、(8.39±1.29)k Pa及(7.08±1.52)k Pa。不同程度肾动脉狭窄时,肾皮质的杨氏模量值均高于肾锥体及肾窦,即肾皮质硬度均大于肾锥体及肾窦,且差异均有统计学意义(肾动脉狭窄0%组:t=11.912、P<0.001,t=4.510,P=0.001;肾动脉狭窄50%组:t=7.116、9.313,P<0.001;肾动脉狭窄100%组:t=7.412、9.125,P<0.001)。随着肾动脉狭窄程度增加,肾皮质、肾锥体、肾窦的杨氏模量值均逐渐降低,即肾皮质、肾锥体、肾窦的硬度均逐渐降低,且差异均有统计学意义(肾皮质:t=2.630、P=0.025,t=6.086、P<0.001,t=3.460、P=0.014;肾锥体:t=7.102、P<0.001,t=3.460、P=0.007;肾窦:t=3.885、P=0.003,t=6.405、P<0.001,t=4.164、P=0.002)。病理结果显示,随着狭窄程度的加重,肾小球体积缩小,其内红细胞减少,肾间质内微血管口径减小,其内红细胞逐渐减少。肾动脉狭窄100%时,局部肾间质可见灶状变性,少量炎细胞浸润,肾小管上皮细胞轻度变性,细胞界限稍模糊。结论兔肾皮质的杨氏模量值高于肾锥体及肾窦,急性肾动脉狭窄时亦是如此。随着急性肾动脉狭窄程度加重,肾皮质、锥体及肾窦的杨氏模量值均逐渐减低,提示动脉狭窄造成的血流动力学改变可明显影响肾脏组织超声弹性测量值。

Objective To study the changes of Young＇s modulus value of the renal cortex, vertebral body and sinus when there was a different degree of acute renal artery stenosis. Methods lO Japanese white rabbits were used for this study. The left renal artery was dissected. An ultrasound probe was placed onthe left kidney, Young＇s modulus of the renal cortex, vertebral body and sinus were recorded using shear wave ultrasound elastic imaging technique during three stages： when the renal artery was intact （0% stenosis）, tied with a suture （ 〉 50% stenosis）, and ligated （100% stenosis）. Renal tissue elasticity with different degrees of renal artery stenosis were compared. Pathological study was carried out in the kidneys, each with either 0%, 〉 50% or 100% renal artery stenosis. Results The mean values of Young＇s modulus from the renal cortex, vertebral body and sinus with different degrees of renal artery stenosis were as follows： 0% stenosis, （16.31 ± 1.70） kPa, （13.38±1.63） kPa, and （12.75±2.26） kPa; 〉 50% stenosis, （14.16±2.34） kPa, （11.49±2.70） kPa, and （10.72±2.56） kPa; 100% stenosis, （11.35± 1.48） kPa, （8.39± 1.29） kPa, and （7.08± 1.52） kPa. The mean value of Young＇s modulus from the renal cortex was significantly higher than those from the renal vertebral body and sinus （P 〈 0.05）. The mean values of Young＇s modulus from different parts of the kidney decreased progressively with an increase in renal artery stenosis （P 〈 0.05）. The pathological study demonstrated that with the increase in the severity of renal artery stenosis, glomerular volume, renal interstitial capillary diameter and red blood cells decreased. When renal artery stenosis reached 100%, there was patch degeneration and inflammatory cell infiltration within the renal interstitium, and mild degeneration of tubular epithelial cells with obscure cell borders. Conclusions The value of Young＇s modulus from the renal cortex was higher than those from the renal pyramid and sinus in rabbits. The values of Young＇s modulus from the renal cortex, pyramid and sinus decreased with an increase in the severity of renal artery stenosis, which suggest that, in the study of the elasticity of the kidney, the renal artery blood flow dynamic state can obviously affect the value of the elasticity of the kidney.