Further studies of toxic material from nematocysts of the cubomedusan Chironex fleckeri southcott

Abstract

Saline extracts of intracapsular material from the nematocysts of C. fleckeri lost their activity against muscle if incubated with protease, heated at 42°, exposed to strong salt solutions, acid solutions of pH 3 and below, alkaline solutions of pH 10·5 and above, iodine, sodium fluoride, sodium iodoacetate or sodium azide. Their activity against muscle was unimpaired in the presence of ouabain or by exposure to EDTA for 5 min. Haemolytic activity was exhibited by extracts; the extracts showed no phospholipase A or proteolytic activity. ATPase activity, inhibited by ouabain, was shown by the extracts. Neither the haemolytic activity or the ATPase activity appeared to be directly associated with the activity shown by the extracts against muscle. No evidence for a release of pharmacologically active products from isolated muscle preparations was obtained. The extracts had no action on glycerinated muscle fibres or on muscles exposed to high K. However, they elicited activity in ‘skinned’ toad muscle fibres and in barnacle muscle fibres after the action potential had been suppressed by Mn ions. The Ca content of barnacle muscle fibre bundles exposed to dilute toxin extracts for 2 min rose markedly but there was a marked decline in the Ca content of bundles exposed to concentrated extracts for 2 min.