Myasthenia gravis is a disease caused when acetylcholine (Ach) receptors on the post synaptic side of the neuromuscular junction are destroyed. What is the role of acetylcholine in muscle function? Insecticides kill insects by blocking the enzyme acetylcholinesterase which breaks down acetylcholine. As a result the insects have uncontrolled muscle contractions and effectively dive exhaustion. How could acetylcholinesterase inhibitors people with myasthenia gravis?

Acetylcholine is the neurotransmitter released from motor nerves. When it combines with receptors on the post synaptic membrane it initiates muscle depolarisation. The acetylcholine must be broken down by the enzyme acetylcholinesterase in order to terminate its effect. Acetylcholinesterase inhibitors are the basic treatment for myasthenia gravis. They work by inhibiting the enzyme and decreasing the breakdown of ACh, increasing the amount of ACh available at the neuromuscular junction. This increases the likelihood that the muscle cell will depolarise.