INFLUENCE OF pH, TEMPERATURE, HALOTHANE AND ITS METABOLITES ON OSMOTIC FRAGILITY OF ERYTHROCYTES OF MALIGNANT HYPERTHERMIA-SUSCEPTIBLE AND RESISTANT PIGS

Erythrocytc fragility of malignant hyperthermia-susccptible and resistant pigs has been examined as a function of pH and temperature in the absence and presence of halothane and its metabolites. A decrease in pH from 7.40 to 6.95 increased the fragility of both susceptible and resistant pigs, but the increase in susceptible animals was significantly greater than that in resistant animals. An increase in temperature led to a reduction of erythrocyte fragility of both types of pig. The most consistent differences in haemolysis between susceptible and resistant pigs occurred at sodium chloride concentrations of 0.120 and 0.137mollitre " '. At all pH values examined and at 39 and 41 °C, but not at 43°C, erythrocytes from susceptible pigs showed greater haemolysis in sodium chloride 0.120 and 0.137mollitre~ ' than did erythrocytes from resistant pigs. Halothane or its metabolites, at concentrations occurring during anaesthesia, did not alter erythrocyte fragility. There is much to suggest that erythrocyte fragility is increased in individuals and swine susceptible to malignant hyperthermia (MH). Harrison and Verburg (1973) found that the median erythrocyte fragility of MH-susceptible pigs lay betwee