Identification of hemolytic and neuroactive fractions in the venom of the sea anemone Bunodosoma cangicum.
Sea anemones are a rich source of biologically active substances. In crayfish muscle fibers, Bunodosoma cangicum whole venom selectively blocks the I K(Ca) currents. In the present study, we report for the first time powerful hemolytic and neuroactive effects present in two different fractions obtained by gel-filtration chromatography from whole venom of B. cangicum. A cytolytic fraction (Bcg-2) with components of molecular mass ranging from 8 to 18 kDa elicited hemolysis of mouse erythrocytes with an EC50 = 14 microg/ml and a maximum dose of 22 microg/ml. The effects of the neuroactive fraction, Bcg-3 (2 to 5 kDa), were studied on isolated crab nerves. This fraction prolonged the compound action potentials by increasing their duration and rise time in a dose-dependent manner. This effect was evident after the washout of the preparation, suggesting the existence of a reversible substance that was initially masking the effects of an irreversible one. In order to elucidate the target of Bcg-3 action, the fraction was applied to a tetraethylammonium-pretreated preparation. An additional increase in action potential duration was observed, suggesting a blockade of a different population of K+ channels or of tetraethylammonium-insensitive channels. Also, tetrodotoxin could not block the action potentials in a Bcg-3-pretreated preparation, suggesting a possible interaction of Bcg-3 with Na+ channels. The present data suggest that B. cangicum venom contains at least two bioactive fractions whose activity on cell membranes seems to differ from the I K(Ca) blockade described previously.
Lagos
P
P
Departamento de Farmacologia, Faculdade de Medicina, Universidade de São Paulo, Ribeirão Preto, SP, Brasil. lagos@usp.br
Duran
R
R
Cerveñansky
C
C
Freitas
J C
JC
Silveira
R
R
D000200:Action Potentials / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D003386:Brachyura / Q000187:drug effects*; D002850:Chromatography, Gel; D003064:Cnidarian Venoms / Q000302:isolation & purification / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects*; D051379:Mice; D009498:Neurotoxins / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects; D012615:Sea Anemones; D015222:Sodium Channels / Q000187:drug effects
D003064:Cnidarian Venoms; D009498:Neurotoxins; D015221:Potassium Channels; D015222:Sodium Channels