Members of the spider genus Phoneutria are commonly called armed spiders, banana spiders for their tendency to hide in banana clumps, or Brazilian wandering spiders for their habit of finding a new resting place each day. They are large, highly aggressive and are known to be the most venomous spiders in the world. They live in tropical regions Central and South America. Brazilian wandering spiders will seek out any available dark and sheltered place to hide during the day, including closets, shoes, cars and clothing. Its fangs are not developed for attacking large prey, making it difficult for these spiders to bite humans. Tx2-6, a component of their venom, is currently being researched for potential medical applications.
The neurotoxin PhTx3 is the most toxic component of the Brazilian wandering spider's venom. This component has a wide variety of systemic effects in the human body. PhTx3 causes excruciating pain due to its powerful stimulating effects on serotonin receptor sites on nerves throughout the body. This stimulation causes an outpouring of pain-promoting chemicals, including "substance P."
The stimulation of the same receptor sites responsible for pain also causes intense, local inflammation by causing the cells to dump out all of the stored inflammatory chemical histamine. This produces redness, heat, swelling and immobility in the area immediately surrounding the bite. The inflammation caused locally can be severe enough to cause the skin, muscle and bone cells in the tissue around the bite to die, causing the flesh to rot away in survivors of the spider's bite.
PhTx3 is also a broad-spectrum calcium channel blocker, much like the common heart medicine Procardia. It inhibits the release of glutamate as well as its absorption by nerve cells, interfering with the part of the nervous system responsible for muscle contraction. This results in increasing levels of muscle paralysis, beginning with a loss of muscle control. At lethal concentrations, this is followed by paralysis, including paralysis of the diaphragm, resulting in death by asphyxiation. In this case, death can be prevented through artificial respiration. Yet higher doses cause paralysis of the heart. Although an antidote exists for the venom, it must be administered extremely quickly, as death can occur in less than 45 minutes.
Tx2-6, another component of Brazilian wandering spider venom, causes intense four-hour penile erections. These erections are quite painful and are caused by a different mechanism than that of Viagra, making this chemical a possible source of a new class of drugs used to treat erectile dysfunction in the human male.
- "Toxicon"; Tarantulas: Eight-Legged Pharmacists and Combinatorial Chemists; May 2004
- Live Science; Natural Viagra: Spider Bite Causes Erection; Jeanna Bryner ; April 2007
- Environmental Graffiti; The Brazilian Wandering Spider: The Most Venomous Spider on Earth; Tony Leather
- "Journal of Toxicology"; Spider Venoms and Spider Toxins; Ori Masahisa and Ikeda Hiroyoshi; December 1998
- Photo Credit Jupiterimages/Photos.com/Getty Images
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