| You may have read newspaper or
magazine articles about the possible use of chemicals during a war or a
terrorist attack. Many of these chemicals affect the nervous system and
are therefore called nerve agents. Nerve agents
are similar to insecticides and they can be deadly if people are exposed
to them. Unfortunately, this has already happened. On March 20, 1995,
twelve people were killed and over 5,000 were injured when a nerve gas
called "sarin" was released in the Tokyo subway system. People may have
also been exposed to nerve agents during the conflict ("Gulf War") in the
Middle East. It is possible that many countries have access to these
dangerous weapons and future human exposure to these chemicals is
possible. In fact, the nerve
agent "VX" is suspected in the attack and death of Kim Jong Nam,
half-brother of North Korean leader Kim Jong Un in February, 2017.|
HistoryMost nerve agents belong to a group of chemicals called "organophosphates". The first of these chemicals was made in 1854 and was originally developed to be used to control insects and save crops. The first nerve agent (called "Tabun" or "GA") for military use was made in Germany in 1936. Another nerve agent, "sarin" or "GB," was made in 1938 and "Soman" or "GD" was made in 1944. It appears that these nerve agents were not used by the Germans during World War II. However, it has been estimated that the Germans had stockpiles of tons of both Tabun and Sarin. The United States and Russia continued producing and stockpiling these nerve agents after the War. In the 1950s another nerve agent, "VX," was produced in England.
Breathing a lethal dose or getting a lethal dose on the skin can kill in only a few minutes! To get an idea of how deadly these chemicals are, do the math.
1 kilogram = 1,000 gm = 2.2 lbs 1 gm = 1,000 mg = 0.0022 lbs 10 mg = 0.000022 lbs10 mg (0.000022 lbs) is not much more than a single grain of rice!!
Nerve agents are clear and colorless and may have no odor or a faint, sweetish smell. They are all extremely dangerous and they can enter the body through the air or on contact with the skin. They can be released using bombs, missiles, spray tanks, rockets and land mines. VX is the most deadly and Tabun is the least deadly (although still very hazardous). Nerve agents are more dense than air so they are especially dangerous to people in low areas.
Method of ActionAcetylcholine is a common neurotransmitter found in the central and peripheral nervous system. When acetylcholine is released from an axon terminal, it moves across the synaptic cleft to bind to a receptor on the other side of the synapse (on the post-synaptic membrane). In the peripheral nervous system, acetylcholine is located at the "neuromuscular junction" where it acts to control muscular contraction. Acetylcholine is also used in the autonomic nervous system. The action of acetylcholine is stopped by an enzyme called "acetylcholinesterase" (AChE).
Nerve agents bind to part of the AChE molecule. This
makes the AChE inactive and blocks the
action of AChE. Therefore,
The Acetylcholine Synapse
Symptoms of Nerve Agent PoisoningNerve agents attack all synapses that use acetylcholine as a neurotransmitter...this means both the central and peripheral nervous systems are affected. Symptoms of nerve agent poisoning include:
Treatment for Nerve Agent ExposureImmediate treatment of person who has been exposed to a nerve agent exposure includes a complete washing of the eyes and skin with water. A diluted (0.5%) bleach solution should also be applied to the skin if possible.
Two drugs, atropine and pralidoxime chloride, have been used as antidotes for nerve agent poisoning. Atropine works by blocking one type of acetylcholine receptor so that the acetylcholine that is already in the synapse cannot work. Pralidoxime works by blocking the binding of the nerve agent to the AChE. Both of these drugs were issued to US troops during the Persian Gulf War in the form of an antidote kit called the Mark I. Diazepam (Valium) may be used to reduce convulsions and seizures brought on by exposure to nerve agents.
Effects of Atropine
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Neuroscience for Kids