The osmotic fragility and critical hemolytic volume of red blood cells of Amazon fishes

Abstract

The osmotic fragility and critical hemolytic volume were determined in red cells obtained from common Amazon fishes including the arawana (Osteoglossum bicirrhosum), the armored catfish (Pterygoplichthys), the electric eel (Electrophorus electrocus), the pirarucu (Arapaima gigas), and the lungfish (Lepidosiren paradoxa). The red cells of the pirarucu and the electric eel displayed the osmotic fragility profile remarkedly akin to human red cells, whereas the red cells of the armored catfish were considerably more resistant to hemolysis than human cells. The arawana cells exhibited a broad shoulder in the region of 120 mM to 70 mM followed by a complete hemolysis near 40 mM NaCl as in other fishes. Unexpectedly, the lungfish red cells were found to be extraordinarily resistant to hemolysis. A 15-min and a 1-h exposure of the lungfish cells to distilled water resulted in hemolysis of 55 and 80%, respectively. The critical hemolytic volume of Amazon fish red cells thus far examined was of the order of 1.83–2.03, except the pirarucu red cells which had a low value of 1.25.