Abstract
The venom of cobra could be divided into three type of toxins that is neurotoxin, cardiotoxin and phospholipase A2. Among these three toxins, the target of cardiotoxin is the only one not clarify yet. The cardiotoxin of cobra venom could divided into two type: S-type and P-type, which is differenciate by the existence of P31 and S29, and the binding affinity toward phospholipid. The previous work show that the cardiotoxin will cause the increase in the concentration of Ca2+ in the cytosol. Beside that apoptosis induced by various molecules also to show the same effect of Ca2+ level in cytosol. Therefore, here we perform the apoptosis study induced by the cardiotoxins. We also elucidate the different apoptosis level between S-type and P-type cardiotoxins.Our result indicated that there are two pathway of cell death induced by cardiotoxins: one is necrosis and the other is apoptosis with the ratio of necrosis is usually higher than apoptosis. The apoptosis phenomena between S-type and P-type showed no significant different, the CTX-A4 perform a slightly higher apoptosis level than other cardiotoxins do. The observation of shrinkage of cell volume, nuclear condensation, sub-G1 fraction, and DNA fragmentation ladder provide us enough evidence of apoptosis occurrence. The early stage of apoptosis effect is the decrease in the mitochondria transmembrane potential. Pretreated with CsA (PTP inhibitor) are proved to be unable to inhibit apoptosis and transmembrane potential decrease. Beside that we also try the broad caspase inhibitor (z-VAD-fmk) which result in no effect of inhibition. This result may be due to the apoptosis induce by CTX-A4 is caspase- independent.