Models of the urinary concentrating mechanism

Abstract

After describing the Kuhn models and outlining their successes and failure, we will describe some of the current modeling efforts. These have taken two general directions. The first emphasizes conservation analysis and qualitative considerations of the permeability characteristics of the various nephron segments. The second relies on numerical solution of the differential equations describing transport in medullary tubules and vasculature to calculate flow and concentration profiles. These computer simulations attempt to correlate transport parameters measured in experiments on isolated renal tubules with data obtained in micropuncture studies, slice studies, or whole kidney experiments. We will conclude by outlining some of the apparent contradictions revealed by these simulations.