Latrotoxin (α-Latrotoxin) found in venom of widow spiders also affects the neuromuscular junction by causing the release of acetylcholine from the presynaptic cell. Mechanisms of action include binding to receptors on the presynaptic cell activating the IP3/DAG pathway and release of calcium from intracellular stores and pore formation resulting in influx of calcium ions directly. Either mechanism causes increased calcium in presynaptic cell, which then leads to release of synaptic vesicles of acetylcholine. Latrotoxin causes pain, muscle contraction and if untreated potentially paralysis and death.
