OF TOXIC EVENTS IN ARSINE-INDUCED HEMOLYSIS IN-VITRO - IMPLICATIONS FOR THE MECHANISM OF TOXICITY IN HUMAN ERYTHROCYTES

Arsine, the hydride of arsenic (AsH3), is the most acutely toxic form of arsenic, causing rapid and severe hemolysis upon exposure. The mech anism of action is not known, and there are few detailed investigation s of the toxicity in a controlled system. To examine arsine hemolysis and understand the importance of various toxic responses, human erythr ocytes were incubated with arsine in vitro, and markers of toxicity we re determined as a function of time. The earliest indicators of damage were changes in sodium and potassium levels. Within 5 min incubation with 1 mM arsine, the cells lost volume central, manifested by leakage of potassium, influx of sodium, and increases in hematocrit. Arsine d id not, however, significantly alter ATP levels nor inhibit ATPases. T hese changes were followed by profound disturbances in membrane ultras tructure (examined by light and electron microscopy). By 10 min, signi ficant numbers of damaged cells formed, and their numbers increased ov er time. These events preceded hemolysis, which was not significant un til 30 min. It has been proposed that arsine interacts with hemoglobin to form toxic hemoglobin oxidation products, and this was also invest igated as a potential cause of hemolysis. Essentially on contact with arsine, methemoglobin was formed but only reached 2-3% of the total ce llular hemoglobin and remained unchanged for up to 90 min. There was n o evidence that further oxidation products (hemin and Heinz bodies) we re formed in this system. Based on these observations, hemolysis appea rs to be dependent on membrane disruption by a mechanism other than he moglobin oxidation. (C) 1997 Society of Toxicology.