atracotoxins

Atracotoxins are a group of neurotoxic peptides found in the venom of Australian funnel-web spiders, primarily belonging to the genus Atrax. These toxins are responsible for the severe envenomation symptoms observed after a bite from these spiders, which can include intense pain, muscle spasms, excessive sweating, and potentially life-threatening cardiovascular and respiratory effects. The most well-studied atracotoxin is delta-atracotoxin-Ar1a, the principal toxic component of the Sydney funnel-web spider's venom (Atrax robustus).

Atracotoxins exert their effects by targeting voltage-gated sodium channels in nerve and muscle cells. They act as potent modulators of these channels, preventing their inactivation and leading to prolonged channel opening. This sustained influx of sodium ions causes repetitive firing of neurons and uncontrolled muscle contractions, ultimately leading to neurotoxicity. While structurally diverse, most atracotoxins share a common structural motif that allows them to bind to specific sites on the sodium channel.

The clinical significance of atracotoxins is considerable due to the potent venom of the spiders that produce them. Fortunately, effective antivenoms have been developed, significantly reducing the mortality rate associated with funnel-web spider bites. Research into atracotoxins has not only aided in understanding their mechanism of action for therapeutic purposes but also contributed to broader knowledge of ion channel physiology.