24 Aug 2017: Chang-Joon Lee

Thu 24 Aug 2017 3:30pm (Murdoch University, Senate Room 121.1.002)

Dude, where’s my oxygen? – A computational study of factors that predispose the kidney to hypoxia

Chang-Joon Lee

School of Engineering and IT, Murdoch University & Faculty of Engineering and Mathematical Sciences, The University of Western Australia

great interest due to the perplexing fact that the kidney is highly susceptible to hypoxia despite being well-supplied with oxygenated blood and having the lowest oxygen extraction ratio of the major organs. One leading hypothesis for this paradox is that a fraction of the oxygen delivered to the kidney never reaches renal tissue, but instead diffuses from arterial to venous segments of the cortical vasculature. However the biological significance of arterial-to-venous (AV) oxygen shunting in the renal cortex remains a matter of controversy.

To assess the physiological significance of AV oxygen shunting and identify other potential factors that may play a major role in renal hypoxia, we generated a new pseudo-three-dimensional computational model of renal cortex based on the cortical vasculature in the rat kidney. The model provides estimates of oxygen tension (PO2) in the renal tissue and how it changes for given combinations of renal oxygen delivery and/or consumption, as well as the magnitude of oxygen shunted from the arterial to venous segments.

While a number of lines of evidence suggest AV shunting is significant, most importantly our computational model predicts AV shunting is small under normal physiological conditions (~0.9% of total renal oxygen delivery), but increases under pathologic states (up to ~3.0% of total renal oxygen delivery). We conclude that AV oxygen shunting normally has only a small impact on renal oxygenation, but may exacerbate renal hypoxia during certain pathologic states. We further conclude that, among other factors that may predispose the kidney to renal hypoxia, renal hypoxia is most likely to be initiated by drastic reduction in the surface area of peritubular capillaries.