Kidney blood flow modeled from structural morphology of renal vasculature in the rat

Abstract

The kidney extracts and excretes urea and other metabolic wastes from the blood, and maintains levels of plasma salt and hydrogen ions by differentially regulating the concentration of these ions in the urine. Since solute and water transport in the kidney is tied to the control and distribution of flow in the vasculature of the kidney, an understanding of renal microcirculatory dynamics is needed to understand the physiological function of this organ.Using dimensional and ordering data obtained from a microtomography (Micro‐CT) study of structural morphology of renal vasculature, separate functions describing the transit time distribution of blood flow through the arterial and venous trees were derived. Separately, three regional microcirculatory models (cortical, juxtamedullary, and shunting) were used to connect the arterial and venous trees. Simulation of the combined model yields a renal intravascular washout function that describes the transit of blood throughout the kidney. Using optimization methods, simulations were fit to experimental data obtained from rat kidney washout studies to estimate functional blood flow to the three microcirculatory beds. This modeling approach can be applied to analyzed data from imaging modalities using contrast measurements in animal studies as well as the clinical setting.