Quantitative estimation of renal blood flow by power Doppler ultrasonography in renovascular hypertensive dogs.
BACKGROUND
We estimated the value of power Doppler (PD) imaging analysis for the quantitative assessment of renal cortical blood flow (RCBF) in chronic two-kidney, one-clip (2K-1C) hypertensive dogs.


METHODS
To evaluate the correlation between RCBF and PD signals, RCBF and the mean pixel intensity (MPI) of PD signals were simultaneously obtained at same region in renal cortex under progressive constriction of left main renal artery in five mongrel dogs. RCBF was measured by electrolytic hydrogen gas clearance method, and PD images were transferred to computer and analyzed by the image-analysis software Openlab. To assess the value of quantitative PD imaging analysis on RCBF in renovascular hypertension, in six mongrel dogs with chronic 2K-1C hypertension, PD images in both of clipped kidneys (CK) and non-clipped kidneys (NK) were obtained and analyzed before and 60 minutes after the intravenous infusion of captopril or sodium nitroprusside at 10-minute intervals.


RESULTS
There was a linear correlation between RCBF and MPI (r= 0.878, P < 0.0001). MPI in both CK and NK significantly increased after the infusion of captopril, while no significant change was observed in both CK and NK after the infusion of sodium nitroprusside, despite similar reduction of mean arterial blood pressure.


CONCLUSIONS
Our data suggest that the acute inhibition of angiotensin-converting enzyme increased RCBF in both CK and NK of chronic 2K-1C dogs. The quantitative analysis of PD flow signals in kidney is noninvasive and a useful method to evaluate regional changes of renal tissue blood flow in various renal diseases.
Miyajima
Tetsumasa
T
Department of Urology, Fukuoka University School of Medicine, Fukuoka, Japan. tetsu@minf.med.fukuoka-u.ac.jp
Yokoyama
Hiroshi
H
Taira
Hiroshi
H
Tsuji
Yuji
Y
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D002216:Captopril / Q000494:pharmacology; D002908:Chronic Disease; D004285:Dogs; D006977:Hypertension, Renal / Q000000981:diagnostic imaging* / Q000188:drug therapy; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D012079:Renal Circulation / Q000187:drug effects; D012083:Renin / Q000097:blood; D012815:Signal Processing, Computer-Assisted; D013525:Surgical Instruments; D018608:Ultrasonography, Doppler / Q000379:methods*
D000959:Antihypertensive Agents; D009599:Nitroprusside; D002216:Captopril; D012083:Renin