Structural organization of the renal medulla has a significant impact on oxygen distribution (890.11)

Abstract

A theoretical model is presented to analyze the impact on oxygen distribution of the heterogeneous organization of the rat outer and inner medulla revealed in anatomical studies.In the inner stripe, tubules and vessels are organized around vascular bundles; in the upper inner medulla, clusters of collecting ducts form the organizing motif. The present study extends a detailed mathematical model of the urine concentrating mechanism of the rat renal medulla developed (Layton, AJP Renal 300: F356‐F371, 2011), which was formulated to represent NaCl and urea, to include transport of red blood cells (RBCs), deoxyhemoglobin (Hb), oxyhemoglobin (HbO2), and free oxygen (O2). Both basal cellular oxygen consumption throughout the whole medulla and active oxygen consumption via active NaCl transport in proximal tubules, thick ascending limbs, and collecting ducts are considered. Model equations are based on conservation of water and solutes, as well as transmural transport, and are solved to steady state. Results from the model suggest that the structural organization of the renal medulla produces significant axial and radial PO2 gradients, and impacts the effectiveness of the medullary urine concentrating mechanism. This research was supported in part by NIH grant DK‐89066.Grant Funding Source: NIH DK089066