Diffusion of sodium in extracellular space of the crystalline lens.

PATERSON, CHRISTOPHER A., AND DAVID M. MAURICE. Di$usion of sodium in extracellular space of the crystalline lens. Am. J. Physiol. 220( 1) : 256-263. 197 1 .-The diffusion coefficients of radioactive ions were measured in bovine lens cortex, which is composed of closely packed long hexagonal cells. Diffusion could therefore be measured a) along the length of the cells, b) at right angles to the cells, parallel to the lens surface, and c) at right angles to the cells, but perpendicular to the surface. From the geometry of the cells, the diffusion coefficients in the extracellular space in the three directions should be in the ratio 100 : 82 : 16 (a: b :c). Experimentally obtained sodium diffusion coefficients were in the ratio 100 : 81: 14. This implies that sodium diffuses almost exclusively in the lens extracellular space. The ratio for potassium and rubidium diffusion coefficients was 100 : 89 : 39, suggesting that different factors control the movement of these ions. The unrestricted (direction a) diffusion coefficient of sodium was 0.97 X 10M5 cm2 see-l, which is within the range reported for the diffusion of sodium in the extracellular space of several tissues” The intracellular potassium diffusion coefficient along direction a (0.98 cm2 set-I) is considerably less than that reported by other investigators. This is considered to be due to the high intracellular protein concentration in the lens.