The lysis of isolated fish (Oncorhynchus mykiss) gill epithelial cells by surfactants

Abstract 1. The interaction of a wide range of surfactants with isolated gill epithelial cells of rainbow trout ( Oncorhynchus mykiss ) was investigated as a function of the surfactant concentration up to and above the critical micelle concentration (cmc). The surfactants included a homologous series of n -alkyl sulphates, single and double chain tri and dimethylammonium bromides (TABs and DABs), cholates and the nonionics n -octylglucoside and Triton X-100. 2. With the exception of the C 22 alkyl chain TAB and the double chain [(C 12 ) 2 ] DAB, the surfactants solubilized between 84 and 100% of the cell protein at high concentrations (>cmc). 3. At low concentrations n -dodecyltrimethylammonium bromide and, to a lesser extent, Triton X-100 and sodium n -dodecylsulphate release a larger proportion of cell protein than they solubilize lipid in contrast to sodium cholate which initially preferentially solubilizes cell lipid. This differential pattern of solubilization is similar to that observed for other plasma membranes such as those of human erythrocytes and platelets. 4. The surfactant concentration required to solubilize 50% ( S 50% ) of cell protein increases with the cmc. There is an approximately linear relationship between log( S 50% ) and log cmc. 5. Light microscopy shows that the surfactants at high concentrations (>cmc) fragment the secondary lamellae of the gill filaments.