title: Noninvasive measurement of concurrent single-kidney perfusion, glomerular filtration, and tubular function.
abstract: To assess the reliability of electron beam computed tomography (EBCT), measurements of single-kidney renal blood flow (RBF), glomerular filtration rate (GFR), and intratubular contrast medium concentration (ITC) of radiographic contrast media were quantified in anesthetized pigs before and after acetylcholine-induced vasodilation and diuresis. EBCT measurements were compared with those obtained with intravascular Doppler and inulin clearance. The capability of EBCT to detect chronic changes in single-kidney function was evaluated in pigs with unilateral renal artery stenosis, and their long-term reproducibility in normal pigs was studied repeatedly at 1-mo intervals. EBCT-RBF (ml/min) correlated with Doppler-RBF as RBF(EBCT) = 45 + 1.07 * RBF(Doppler), r = 0.81. EBCT-GFR (ml/min) correlated with inulin clearance as GFR(EBCT) = 11.7 + 1.02 * GFR(inulin), r = 0.80. During vasodilation, RBF and GFR increased, whereas ITC decreased along the nephron. In renal artery stenosis, single-kidney GFR decreased linearly with the degree of stenosis, and ITC increased along the nephron, indicating increased fluid reabsorption. EBCT-RBF, GFR, and ITC were similar among repeated measurements. This approach might be invaluable for simultaneous quantification of regional hemodynamics and function in the intact kidneys, in a manner potentially applicable to humans.
authors.affiliation: Division of Hypertension, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Krier
authors.forename: E L
authors.initials: EL
authors.lastname: Ritman
authors.forename: Z
authors.initials: Z
authors.lastname: Bajzer
authors.forename: J C
authors.initials: JC
authors.lastname: Romero
authors.forename: A
authors.initials: A
authors.lastname: Lerman
authors.forename: L O
authors.initials: LO
authors.lastname: Lerman
mesh_terms: D000818:Animals; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D007444:Inulin / Q000493:pharmacokinetics; D007668:Kidney / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology; D007684:Kidney Tubules / Q000502:physiology*; D017078:Laser-Doppler Flowmetry; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging*; D012079:Renal Circulation / Q000502:physiology*; D015203:Reproducibility of Results; D013552:Swine; D014057:Tomography, X-Ray Computed
chemical_list: D007444:Inulin