Fish venoms can be lethal for Vertebrates. The effect depends of dose and subject, more than incriminated fish. The most constant symptom is a violent
pain; but the serious pharmacological effects are respiratory and
heart failure with marked
hypotension and cardiac perturbations, neurologic damage, such as seizure and
coma. Experimentation is difficult due to
venom instability. Activity is lost by distilled water, lyophilisation in
buffers, several successive freezing and defreezing. In addition, when
venom is broken, other pharmacological effects are evidenced, for instance, with Synanceia verrucosa
venom, hypertensive phase takes the place of
hypotension. It is difficult to distinguish toxin effect from this of denaturation products of the toxin.
Noradrenaline is present in Synanceia
venom, and it seems that
acetylcholine exists in some
venom, at least when diluted in
saline solution. Other
biological active products are present. Purified toxins allow pharmacological investigations. Stonefish
venom is better studied, because venomous glands contain relatively high
venom quantity.
Stonustoxin from Synanceia horrida exerts its action through
NO-synthase liberation, and its primary action can be attributed to its potent
vasorelaxant activity, causing a rapid, marked and irreversible
hypotension.
Trachynilysin, from Synanceia trachynis, causes massive release and depletion of
acetylcholine and damage to nerve and muscle fibres, which can account for the inhibition of neuromuscular function, and skeletal
paralysis. But the used doses are not compatible with respiratory arrest. Verrucotoxin from Synanceia verrucosa activates
potassium channels dependent from
ATP; this can explain damage, and probably neurologic and respiratory distress.