Spring 2016 – Effects of proximal tubule-capillary interaction on renal function

Most fluid reabsorption in the kidney occurs in the nephron’s proximal tubule (~65%). Alhough the equations governing flows across proximal tubule and peritubular capillary membranes are known, interaction among the mechanical properties balancing tubule reabsorption and capillary uptake has yet to be elucidated. Current understanding of tubular-capillary fluid balance is therefore piecemeal; and experimental design and interpretation remain difficult. While computational models have examined tubular reabsorption, numerical solutions are particularly sensitive and specific to chosen parameters and do not qualify underlying mechanics of multi-dimensional systems well. Two tools have yet to be applied: analytical and graphical balance point methods. Analytical approaches provide generalized algebraic solutions that reveal the qualitative relationships among mechanical properties. Balance point analysis can also be used to understand how complex subsystems interact. Therefore, the purpose of the present work is to provide analytical solutions and graphical balance point representation to characterize complex mechanical interactions underlying tubular-capillary fluid balance.