Venom Information
- Komodo dragons produce a venom that contains a small cocktail of toxins that cause effects such as peripheral vasodilation of areas around the bite area, causing an increase in vascular permeability (5). The increased vascular permeability leads to extreme hypotension in the victim, which is a severe lowering of blood pressure. The Komodo dragon's toxins have been categorized based on their action within the body, and are classified as follows:
- Natriuretic-type toxins: Causes an increase in vascular permeability and dilation, leading to hypotension
- Kallikrein toxin: Assists in causing hypotension, also causes pain
- PLA2 toxin: Phospholipase that alters blood chemistry; causes blood to become anti-coagulative
- CRISP toxin: Assists in causing hypotension
- AVIT toxin: Helps immobilize prey by causing hyperalgesic cramping
Natriuretic Type Peptides
- Natriuretic-type peptides are a major component that are found in the venom of Varanus komodoensis and thus will be our focus. These peptides have been found to cause dilation of blood vessels in order to lower blood pressure are create shock-like symptoms in potential prey. Using the LD50 measurement system of toxicity, the natriuretic peptides found in V. komodoensis venom is lethal in 50% of administered mice at a dosage ratio of 0.4mg of venom per 1 kg of victim weight. Not much is known about these specific types of peptides that are used in V. komodoensis venom, but the homology between peptides found in other vertebrate systems provide the best speculation to how they function. These peptides were given the name of natriuretic-type peptides due to their high sequence and structure homology to natriuretic peptides that are found in human systems. Humans contain natriuretic peptides and hormones that are responsible for facilitating functions such as:
- (1)vasodilation, which is the dilation of blood vessels to cause lowering of blood pressure,
- (2)diuretic properties, which promotes urine production and urination (facilitates excretion)
- (3)natriuretic properties, which promote the excretion of excess sodium via urination.
- Sequence homologies have revealed that the natriuretic-type peptides are very similar to human natriuretic peptides and hormones. Both V. komodoensis natriuretic-type peptides and H. sapiens natriuretic peptides contain rounghly 120-130 long amino acid sequences (2) Certain regions of the natriuretic peptides in humans have been linked to certain functions such as altering ionic channels (6), and it would be speculated that the natriuretic-type peptides work in similar fashion.