Cardiotoxicity of verrucotoxin, a protein isolated from the venom of Synanceia verrucosa.
Freshly purified but unstable verrucotoxin (VTX) and a more stable proteic complex of the toxin (p-VTX) were isolated from the venom of the stonefish Synanceia verrucosa and applied to frog atrial fibres. VTX and p-VTX decreased the amplitude and the duration of the stimulated peak tension and accelerated the relaxation phase of the contraction. The negative inotropic effect of p-VTX decreased with increasing the external Ca concentration ([Ca]o) in the Ringer solution. The negative chronotropic effect induced by p-VTX was insensitive to change in [Ca]o. It is reversed by glibenclamide. p-VTX shortened the duration of the plateau and the repolarizing phase of the action potential. Glibenclamide but not tetraethylammonium reversed the p-VTX-induced shortening of the AP repolarizing phase. The data suggest that the toxin isolated from the venom of S. verrucosa inhibits Ca channels and might activate ATP-sensitive potassium channels in frog atrial heart muscle.
Garnier
P
P
Laboratoire de Biologie Animale, Faculté de Pharmacie Université de Paris Sud, France.
Sauviat
M P
MP
Goudey-Perriere
F
F
Perriere
C
C
D000818:Animals; D016275:Atrial Function; D004558:Electric Stimulation; D005397:Fish Venoms / Q000633:toxicity*; D005400:Fishes, Poisonous; D006023:Glycoproteins / Q000302:isolation & purification / Q000633:toxicity*; D006325:Heart Atria / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D009498:Neurotoxins / Q000633:toxicity*; D011506:Proteins / Q000633:toxicity; D011893:Rana esculenta
D005397:Fish Venoms; D006023:Glycoproteins; D009498:Neurotoxins; D011506:Proteins; C094408:verrucotoxin protein, Synanceia verrucosa