Permeability Characteristics of Ovine Primordial Follicles Calculated with Two Parameter Kedem-Katchalsky Formulation

Abstract

The osmotic responses of isolated ovine primordial follicles when suspended in various concentrations of several cryoprotective additives (CPAs) have recently been published. We have used the Kedem-Katchalsky formulation, written with two parameters as variables, to calculate permeability of the follicle membrane to water, Lp, and permeability to CPAs, ω. By fitting the model to the osmotic responses of follicles determined by Amorim and colleagues, we were able to calculate the permeability coefficients in the presence of 0.5, 1.0, 1.5, 2.0, or 2.5 M solutions of each of the following CPAs: dimethylsulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PROH), and glycerol (GLY). In the presence of DMSO, the best-fit values of L p ranged from 0.15 to 0.29 × 10-14 m 3/N-sec, and ω ranged from 0.30 to 0.50 × 10 -11 mol/N-sec. In the presence of EG, the corresponding values of Lp ranged from 0.25 to 0.47 × 10-14 m 3/N-sec, and ω ranged from 0.20 to 0.65 × 10 -11 mol/N-sec. In the presence of PROH, Lp ranged from 0.10 to 0.62 × 10-14 m3/N-sec, and ω ranged from 0.10 to 0.40 × 10-11 mol/N-sec. And finally, in the presence of GLY, the best-fit values of Lp ranged from 0.19 to 0.32 × 10-14 m3/N-sec, and ω ranged from 0.05 to 0.32 × 10-11 mol/N-sec. The cross correlation or the reflection coefficient, σ, defined as σ = 1 - ωυCPA/ Lp, where υCPA is the partial mole volume of the CPA, ranged from 0.763 to 0.926 in the presence of DMSO, from 0.870 to 0.977 in the presence of EG, from 0.813 to 0.983 in the presence of PROH, and from 0.918 to 0.988 in the presence of GLY. These values of Lp and ω (and σ) can be used to predict the volumetric response of ovine follicles under arbitrary CPA loading and unloading conditions and consequently, the presumptive optimal conditions. © Mary Ann Liebert, Inc.