Muscle and nerve toxins Flashcards
What are potential sources of tetrodotoxin
Ingestion of animal containing tetrodotoxin - puffer fish
Bitten/stung by an animal with tetrodotoxin - blue ringed octupus
Is tetrodotoxin produced by the animals in which the sources arise
No, marine bacteria located in the animal produce it - symbiotic relationship - unclear as to how the animals show immunity to the toxin
What are some symptoms of tetrodotoxin
Numbness in lips and tongue, headache, vomiting, increased levels of paralysis, respiratory muscle paralysis leads to death (20mins-8hours)
What is the treatment for tetrodotoxin
Keep alive until tetrodotoxin is broken down by the body
Mechanically ventilate the patient to prevent death by respiratory paralysis - allows this time
What is the action of tetrodotoxin
Blocking of Nav channels
No action potential in motor/sensory neurons
Reduction in neurotransmitter release at the neuromuscular junction - No muscular action potential produced leading to paralysis
Which Nav channels are sensitive to tetrodotoxin
- 1,2,3,4,6,7
1. 5,8,9 are insensitive channels
What are sources of dendrotoxins
Snake neurotoxins, mamba snake family
What are the symptoms of dendrotoxins
Early weakness/numbness at bite site
Ptosis - drooping eyelids, dysphagia (difficulty swallowing), Paresis (mild general paralysis around the body), Resp failure leads to death
What is the physiology of dendrotoxins
Blockage of Kv channels - depolarisation lasts longer so depletion of Ach stores at the presynapse
No more Ach to release results in no action potentials so no contraction
How do dendrotoxins affect K channels
Decrease K current to 25%
How are dendrotoxins treated
Antivenom, removes toxin from bound channels, prevents binding with channels
What are conotoxin sources
Cone snails
What is the target of conotoxins
Cav2.2 and Nav1.8 - block the channels in peripheral and CNS - may be beneficial for blocking pain signals
Conotoxin symptoms
Burning pain - paradoxically short term symptom due to nociceptor stimulation
Swelling at site
Numbness, CV and resp distress, loss of coordination, nausea, stomach cramp
