Effect of erabutoxin on respiration of rabbits

The effect of erabutoxin (ETX) was examined on respiration of rabbits. A single dose of 15 microgram/kg or 25 microgram/kg of ETX did not cause respiratory paralysis, but repeated administration of 15 microgram/kg of ETX at 3 hour intervals (three times) or 25 microgram/kg at 4 hour intervals (twice) caused fatal respiratory paralysis. Furthermore, a single administration of 50 microgram/kg of ETX caused fatal respiratory paralysis within 2 hours after the administration in all animals. This respiratory paralysis caused by ETX was reversible and of long duration (10-20 hour). This respiratory paralysis was not blocked by the administration of anticurare agents (neostigmine, edrophonium) or respiratory stimulants (nikethamide, picrotoxin, dimorpholamine). Since ETX had no influence on the circulatory system, death caused by ETX was prevented with application of artificial respiration.