Study of conductance with pericardium: effect of binding site asymmetry on conductance of ions

Abstract

The observed values of specific conductance of different uni-univalent and uni-bivalent electrolytes were measured with the uptake side, discharge side and across the pericardial membrane in an experimental setup developed in our laboratory. The values of specific conductance (K) were found to be increased with the increase in concentration of the different electrolyte and attain maximum limiting value. The sequence of observed specific conductance for the alkali chlorides and sulphate under the same condition was found to be Na2SO4 > KCl > NaCl > LiCl which is in accordance with their ionic concentration and ionic radii order. The values of specific conductance of all the electrolytes were found different for the uptake side (Kup), discharge side (Kdis) and across the membrane (Kac). The order of three kinds under identical condition being: Kup > Kdis > Kac. This sequence is in good accordance with the higher ion binding affinity of the uptake side than discharge side of the membrane and the asymmetric location of ion binding site with respect to the two sides of pericardium. This asymmetricity of binding site is most likely to cause the variation in the values of Kup and Kdis. The corresponding values of Kac is the lowest which seems to be due to the lower value of dielectric constant of the channel medium of the protein membrane interior than the aqueous phase on both sides of the membrane. In this study the outer layer of pericardium behaved as an uptake side and inner layer as a discharge side.