According to experiments with rodents,<unk>  is one of the most potent alkaloids known: its intravenous in mice is 2-3 µg/kg. Meanwhile, its derivative,<unk> in A, has a much lower toxicity with an of 1000 µg/kg. The toxin is released through colourless or milky secretions from glands located on the back and behind the ears of frogs from the genus Phyllobates. When one of these frogs is agitated, feels threatened or is in pain, the toxin is reflexively released through several canals. Neurotoxicity As a neurotoxin, it affects the nervous system. Neurological function depends on depolarization of nerve and muscle fibres due to increased sodium ion permeability of the excitable cell membrane. Lipid-soluble toxins such as<unk>  act directly on sodium ion channels involved in action potential generation and by modifying both their ion selectivity and voltage sensitivity.<unk>  irreversibly binds to the Na+ channels which causes a conformational change in the channels that forces the sodium channels to remain open.<unk>  not only keeps voltage-gated sodium channels open but also reduces single-channel conductance. In other words, the toxin binds to the sodium channel and keeps the membrane permeable to sodium ions in an "all or none" manner. This has a direct effect on the peripheral nervous system (PNS).<unk>  in the PNS produces increased permeability (selective and irreversible) of the resting cell membrane to sodium ions, without changing potassium or calcium concentration. This influx of sodium depolarizes the formerly polarized cell membrane.<unk>  also alters the ion selectivity of the ion channel by increasing the permeability of the channel toward larger cations. Voltage-sensitive sodium channels become persistently active at the resting membrane potential.<unk>  kills by permanently blocking nerve signal transmission to the muscles.<unk>  binds to and irreversibly opens the sodium channels of nerve cells and prevents them from closing. The neuron can no longer send signals and this results in paralysis. Although generally classified as a neurotoxin,<unk>  has marked effects on heart muscles and its effects are mediated through sodium channel activation. Heart conduction is impaired resulting in arrhythmias, extrasystoles, ventricular fibrillation and other changes which lead to asystole and cardiac arrest.<unk>  induces a massive release of acetylcholine in nerves and muscles and destruction of synaptic vesicles, as well.<unk>  R is more toxic than related<unk>  A. Structural changes in nerves and muscles are due to a massive influx of sodium ions, which produces osmotic alterations. It has been suggested that there may also be an effect on the central nervous system, although it is not currently known what such an effect may be.<unk>  activity is temperature-dependent, with a maximum activity at . Its activity is also more rapid at an alkaline pH, which suggests that the unprotonated form may be more active.
Batrachotoxin
Psalmotoxin
Staphylotoxin
Jingzhaotoxin
Vanillotoxin
Conotoxin
Bungarotoxin
Maitotoxin