Primary action of Clostridium perfringens type A enterotoxin on HeLa and Vero cells in the absence of extracellular calcium: rapid and characteristic changes in membrane permeability.

Clostridium perfringens type A enterotoxin bound rapidly to HeLa and Vero cells in the absence of extracellular Ca2+ at 37 degrees C. The bound toxin rapidly (within 2 min) caused influx of Na+ and efflux of K+ and Mg2+. Changes in membrane permeability occurred in the absence or presence of extracellular Ca2+ and to the similar extents at 37 degrees C and 4 degrees C, in contrast to the subsequent bleb and balloon formation, which required both extracellular Ca2+ and incubation at 37 degrees C. Substances with molecular weights of over ca. 200 protected the cells from the morphological alterations induced by the toxin, whereas substances with molecular weights of less than ca. 200 did not. The mechanism of the primary action of the enterotoxin is discussed.