Abstract
The effects of tetrachlorobiphenyl (TCB) isomers on the osmotic fragility and shape of human erythrocytes were examined. Low concentrations of 2, 3, 2', 3'-, 2, 4, 2', 4'-and 2, 5, 2', 5'-TCB protected erythrocytes from hypotonic hemolysis, but at high concentrations, these compounds greatly promoted hypotonic hemolysis. Along with the anti-hemolytic effect, the compounds caused alterations in cell shape that ranged from normal discocytes to cup-formed cells and to spherocytes. Thus, these compounds can be classified as cup-formers. The alterations in shape were brought about by conditions in which the membranes were protected from hypotonic hemolysis. The break point in the Arrhenius plot for hypotonic hemolysis was decreased by about 3°C when 2, 3, 2', 3'-TCB was added. Therefore, these compounds increase fluidity of the bilayer, which is clearly demonstrated by the ability of 2, 3, 2', 3'-TCB to lower the break point temperature, which enables it to protect erythrocytes from osmotic swelling. By contrast, 2, 6, 2', 6'-and 3, 4, 3', 4'-TCB neither protected erythrocytes from hypotonic hemolysis nor altered cell shape. The relation between these phenomena and chemical structure is discussed.
