The effect of dithiothreitol on the activity of tityustoxin from the scorpion Tityus serrulatus venom.

The acetylcholine (ACh) liberating effect on rat brain slices of tityustoxin, an alpha toxin from the scorpion Tityus serrulatus venom, was measured in the absence and presence of dithiothreitol (DTT). The rate of net ACh liberation by toxin concentrations of 2 nmol in 5 ml of organ bath, was 7.5 +/- 0.09 nmol g-1 min-1. If DTT at a final concentration of 1 mM was added after a 10-min incubation period with toxin alone, inhibition of tityustoxin activity was 94%. With DTT 0.1 or 0.01 mmolar inhibition was 74% and 57%, respectively. The intense secretagogue effect, both in salivary and pancreatic glands of adult rats, induced by sublethal doses of tityustoxin was not affected by i.v. injection 10 min later of DTT 1 mumol g-1 of rat weight. When tityustoxin was injected i.p. at a dose 3 times the LD50 in mice, death ensued in 40 to 60 min. If toxin inoculation in mice was followed 10 min later by DTT 1 mumol g-1 of mouse weight, injected i.p. or i.v., deaths were delayed to 90 to 110 min, but no survival was observed. At necropsy, none of the mice treated with DTT showed any signs of pulmonary edema.