Permeation of glycerol and propane-1,2-diol into human platelets

The permeability of human platelets to glycerol (GLY) and propane-1,2-diol (propylene glycol, PG) has been determined by measuring the time course of their change in volume following abrupt immersion in solutions of these solutes. A simple light-scattering method, and its calibration to measure mean platelet volume is described. The data are analyzed by means of the Kedem-Katchalsky (K-K) equations, modified to take into account the nonideal behavior of both intracellular and extracelular solutes. The values of the K-K parameters at 2, 21, and 37 °C, respectively, were as follows: the hydraulic conductivities ( L p) were 1 × 10 −7, 7 × 10 −7 and 3 × 10 −6 cm · sec −1 · atm −1; the solute permeabilities for PG (ω RT PG) were 1.9 × 10 −6, 2.8 × 10 −5, and 1.3 × 10 −4 cm · sec −1; the solute permeabilities for GLY (ω RT GLY), at 21 and 37 °C only, were 2.6 × 10 − and 1.4 × 10 −6 cm · sec −1. The reflection coefficient (σ) was 1 throughout. The relevant activation energies were - L P 16.5 kcal · mol −1; ω RT PG, 20.5 kcal · mol −1; and ω RT GLY, 17.9 kcal · mol −1. The use of these data is illustrated by computing schedules for the addition and removal of GLY and PG so that the amplitudes of changes in platelet volume are held within predetermined limits.