Validation of miniature ultrasonic transit-time flow probes for measurement of renal blood flow in rats.
This study validates the accuracy of miniature ultrasonic transit-time flow probes for measuring renal blood flow (RBF) in the rat. Probes for 1-mm and 2-mm vessels were calibrated ex vivo using excised arteries at varying flow rates and hematocrit (Hct). Correlation between measured and true flow rates for the 2-mm probe were identical (r = 1.0) at both normal and subnormal Hct values. Correlation for the 1-mm probe was high (r = 0.994) at normal Hct, but varied at both high flow rates and subnormal Hct values. In vivo correlation of RBF measurements using the 1-mm probe with the clearance and extraction of p-aminohippuric acid showed a high correlation (r = 0.84; n = 72, P < 0.0001) over a wide range of flow rates (0.5-21 ml/min) and Hct (36-74%). Zero flow levels remained steady, averaging -0.2 +/- 0.2 ml/min during occlusion in the living animal and -0.1 +/- 0.3 ml/min after exsanguination. This study shows that the ultrasonic transit-time flowmeter (1-mm and 2-mm probes) is a reasonably accurate and reliable method with which to measure RBF in the anesthetized, acute-instrumented rat.
Division of Nephrology, University of Florida, Gainesville.
W J
WJ
Welch
X
X
Deng
H
H
Snellen
C S
CS
Wilcox
D000818:Animals; D002250:Carbon Radioisotopes; D006400:Hematocrit; D007668:Kidney / Q000098:blood supply*; D051381:Rats; D012039:Regional Blood Flow; D012044:Regression Analysis; D012212:Rheology; D013997:Time Factors; D014465:Ultrasonics; D010130:p-Aminohippuric Acid
D002250:Carbon Radioisotopes; D010130:p-Aminohippuric Acid