Accidents by Thalassophryne nattereri
fish venom are characterised by severe local symptoms and signs including
pain of fast onset, oedema and
necrosis with impaired muscle regeneration. These effects have been related to alterations in
hemostatic mechanisms and cytolytic effects rather than to conventional inflammatory pathways. In this work we evaluated the effects induced by the
venom on microcirculatory vessels, platelets and blood coagulation. Effects evoked by topical application of
venom on cremaster muscle were visualised through intravital microscopy. Stasis was observed, concomitantly with the presence of thrombi in venules and focal transient constrictions in arterioles, all of which impaired the blood flow. Significant alterations on vessel walls took place few minutes after
venom application, characterised by increment in thickness, probably by deposition of
fibrin. Increase in vascular permeability was also observed in venules. Additionally, the action of the
venom was locally restricted since no alteration on systemic blood coagulation was observed.
Venom lacked a direct pro-
coagulant activity, but exerted a strong cytolytic effect on platelets and endothelial cells in vitro. These data suggest that
venom action on endothelium may contribute to blood stasis and to the formation of platelet and
fibrin thrombi, with the consequent
ischemia, contributing to the local effects of the
venom.