AJP - Renal Physiology, Vol 269, Issue 4 571-F580, Copyright © 1995 by American Physiological Society
Noninvasive measurement of intrarenal blood flow distribution: kinetic model of renal 123I-hippuran handling
W. M. Janssen, H. Beekhuis, R. de Bruin, P. E. de Jong and D. de Zeeuw
Department of Medicine, University of Groningen, The Netherlands.
A new technique for noninvasive measurement of intrarenal blood flow
distribution over cortex and medulla is proposed. The technique involves
analysis of 123I-labeled hippuran renography, according to a kinetic model
that describes the flow of 123I-hippuran from the heart (input) through the
renal cortex and medulla to the bladder (output). The method is validated
and compared with the standard microsphere injection technique in
anesthetized dogs. Changes in intrarenal blood flow distribution were
induced by infusion of placebo (n = 6), angiotensin I (n = 5), or atrial
natriuretic factor (n = 5). Baseline percentage medullary blood flow in the
left kidney was 12 +/- 1% of total renal blood flow measured with
microspheres and 15 +/- 1% with renography. During infusion of the placebo,
medullary blood flow decreased slightly compared with baseline, as measured
with both methods, by 2 +/- 6 (microspheres) and 1 +/- 8% (renography).
Infusion of angiotensin I caused a marked fall in medullary blood flow by
42 +/- 11 (microspheres) and 57 +/- 8% (renography). In contrast, infusion
of atrial natriuretic factor caused a small rise in medullary blood flow as
measured with both methods (9 +/- 3 and 12 +/- 11%, respectively). The
absolute and percent changes in medullary blood flow measured with
renography correlated with those measured with microspheres (left kidney: r
= 0.67, P = 0.005; r = 0.71, P = 0.003, respectively; right kidney: r =
0.62, P = 0.01; r = 0.68, P = 0.004, respectively). We conclude that the
proposed kinetic model of renal 123I-hippuran handling can be used to
measure changes in intrarenal blood flow distribution and, because of its
noninvasive character, may be of use in clinical studies.
