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02-08-2013, 03:08 PM
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The Spider Bite That Gives You an Erection for Hours
Phoneutria, commonly known as Brazilian wandering spiders, armed spiders ("armadeiras", as they are known in Portuguese), or banana spiders (not to be confused with the relatively harmless Nephila), are a genus of defensive and venomous spiders of potential medical significance to humans. They are mainly found in tropical South America, with one species in Central America. These spiders are members of the Ctenidae family of wandering spiders. The Brazilian wandering spiders appear in Guinness World Records from 2010 as the world's most venomous spider. However, several venomous species of arachnid are far more likely to attack a human, and the Guinness book of World Records states that although the Brazilian wandering spider is the most toxic, more deaths actually occur from black widow and brown recluse spider bites, due to the rarity of the Wandering spider biting anyone. Wandering spiders are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web. During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants and bromeliads. P. nigriventer is known to hide in dark and moist places in or near human dwellings. P. nigriventer mates during the dry season from April to June, which leads to frequent observations of the species during this time. P. fera and P. nigriventer are widely considered the most venomous species of spider. Its venom contains a potent neurotoxin, known as PhTx3, which acts as a broad-spectrum calcium channel blocker that inhibits glutamate release, calcium uptake and also glutamate uptake in neural synapses. At deadly concentrations, this neurotoxin causes loss of muscle control and breathing problems, resulting in paralysis and eventual asphyxiation. In addition, the venom causes intense pain and inflammation following a bite due to an excitatory effect the venom has on the serotonin 5-HT4 receptors of sensory nerves. This sensory nerve stimulation causes a release of neuropeptides such as substance P which triggers inflammation and pain. Aside from causing intense pain, the venom of the spider can also cause priapism in humans. Erections resulting from the bite are uncomfortable, can last for many hours and can lead to impotence. A component of the venom (Tx2-6) is being studied for use in erectile dysfunction treatments. The amount of P. nigriventer venom necessary to kill a 20 g mouse has been shown to be only 6 μg intravenously and 134 μg subcutaneously as compared to 110 μg and 200 μg respectively for Latrodectus mactans (Southern black widow). This ranks Phoneutria venom among the most deadly spider venoms to mice. http://en.wikipedia.org/wiki/Brazilian_wandering_spider |