A pseudo-three-dimensional model for quantification of oxygen diffusion from preglomerular arteries to renal tissue and renal venous blood

• Published in: American journal of physiology. Renal physiology Vol. 313; no. 2; p. F237
• Main Authors: Lee, Chang-Joon, Ngo, Jennifer P, Kar, Saptarshi, Gardiner, Bruce S, Evans, Roger G, Smith, David W
• Format: Journal Article
• Language: English
• Published: United States 01-08-2017
• Subjects: Animals; Cardiovascular Diseases - blood; Cardiovascular Diseases - physiopathology; Cell Hypoxia; Computer Simulation; Diffusion; Glomerular Filtration Rate; Ischemia - blood; Ischemia - physiopathology; Kidney - blood supply; Kidney - metabolism; Models, Cardiovascular; Oxygen - blood; Oxygen Consumption; Rats; Renal Artery - diagnostic imaging; Renal Artery - physiology; Renal Circulation; Renal Veins - diagnostic imaging; Renal Veins - physiology; Reproducibility of Results; X-Ray Microtomography; arterial-to-venous oxygen shunting; computational model; renal oxygenation
• ISSN: 1522-1466
• DOI: 10.1152/ajprenal.00659.2016

To assess the physiological significance of arterial-to-venous (AV) oxygen shunting, we generated a new pseudo-three-dimensional computational model of oxygen diffusion from intrarenal arteries to cortical tissue and veins. The model combines the 11 branching levels (known as "Strahler" orders) of the preglomerular renal vasculature in the rat, with an analysis of an extensive data set obtained using light microscopy to estimate oxygen mass transfer coefficients for each Strahler order. Furthermore, the AV shunting model is now set within a global oxygen transport model that includes transport from arteries, glomeruli, peritubular capillaries, and veins to tissue. While a number of lines of evidence suggest AV shunting is significant, most importantly, our AV oxygen shunting model predicts AV shunting is small under normal physiological conditions (~0.9% of total renal oxygen delivery; range 0.4-1.4%), but increases during renal ischemia, glomerular hyperfiltration (~2.1% of total renal oxygen delivery; range 0.84-3.36%), and some cardiovascular disease states (~3.0% of total renal oxygen delivery; range 1.2-4.8%). Under normal physiological conditions, blood Po
is predicted to fall by ~16 mmHg from the root of the renal artery to glomerular entry, with AV oxygen shunting contributing ~40% and oxygen diffusion from arteries to tissue contributing ~60% of this decline. Arterial Po
is predicted to fall most rapidly from Strahler
, under normal physiological conditions. We conclude that AV oxygen shunting normally has only a small impact on renal oxygenation, but may exacerbate renal hypoxia during renal ischemia, hyperfiltration, and some cardiovascular disease states.