Determination of Renal Hemodynamic Parameters with RDUS

The RDUS technique, which is considered to be the first clinical imaging technique with the hallmarks of being readily available, safe and noninvasive,¹⁶ was used to detect renal hemodynamic parameters of blood flow changes after the DN stage was confirmed.

At the end of the 13th week, the rats were fasted but with water overnight and anesthetized with intraperitoneal injection of 35 mg/kg pentobarbitone sodium (Solarbio Technology Company, Beijing, China) in the morning. Doppler ultrasound examination (MyLab 60 equipment (Esaote, Genova, Italy) with a 4~13 MHz transducer (LA523)) of the left kidney was performed by two experienced sonographers. The examination was performed as follows: the abdomen was depilated and cleaned, and the ultrasonic coupling agent was applied appropriately. To display the kidney well, the sonographer adjusted the probe angle, image depth, gain, and focus. When the color Doppler procedure was activated, the sonographer adjusted the probe angle again so that the main renal artery and intrarenal branches, including segmental arteries and interlobar arteries, were displayed well. Hemodynamic parameters were measured by pulse Doppler with a sampling volume of 0.5 mm and an angle less than 60°.

After obtaining a stable flow spectrum, peak systolic velocity (PSV), end-diastolic flow velocity (EDV) and mean velocity (MV) were measured in the main, segmental and interlobar arteries. The pulsatility index (PI) was calculated based on the above indices.¹⁷

The resistive index (RI) was also calculated based on the above indices.¹⁸

PSV, EDV and MV were measured three times in each rat, and the mean value was calculated. PI and RI were calculated from the three measurements, and the mean value was taken.