ORGANIC SOLUTE PERMEABILITY IN ERYTHROCYTES OF THE LITTLE SKATE, RAJA-ERINACEA

Neutral, organic molecules with seven or less major atoms permeate ery throcytes of the little skate (Raja erinacea). Hypotonicity (80%) incr eased permeation up to 10-fold. Under both isotonic and hypotonic cond itions solute influx occurred with the same size limitation, indicatin g that the number of permeation sites, but not their size, increases w ith hypotonicity. The maximum average diameter of these neutral molecu les that penetrate the cell membrane is about 5.6 to 6.2 angstrom. Thi s is similar to that found previously for amino acid permeation, but u nlike amino acids, the entry of most of the organic, neutral molecules into skate erythrocytes is not affected by Band 3 inhibitors. These r esults suggest that the neutral molecules tested may enter the erythro cytes via the same channel as amino acids, but do not interact with th e sites blocked by Band 3 inhibitors, or through a separate channel of similar size which is also volume activated. (C) 1993 Wiley-Liss, Inc .