Computation of the osmotic water permeability of perfused tubule segments

Abstract

In this technical note the hydraulic conductivity of tubule segments is calculated from measurements made from in vitro perfusion of isolated tubules. The variables include the resorbed volume/minute, the area of the membrane, the reflection coefficient of the solute and the mean difference between the osmotic pressures of the bath and the luminal fluid. Calculations on the arithmetic or on the logarithmic means may give values which are significantly different from the exact analytical solution. Six equations are produced to compute a seventh which allows for a more accurate calculation of hydraulic conductivity near conditions of osmotic equilibrium. (Parsons - London)