What, exactly, poisoned Russian activist?
Blood tests confirmed the presence of nerve agent that overstimulates system
Alexei Navalny took a few sips of tea at the airport in Tomsk, Siberia, before boarding a plane bound for Moscow. On the flight he became so ill that the plane had to make an emergency landing in Omsk where the doctors suspected but were unable to confirm some sort of drug overdose.
Since Navalny was an activist who had been investigating government corruption in Russia, and had previously claimed to have been sprayed by some sort of toxic chemical by assailants, a German humanitarian organization, Cinema for Peace, took an interest in the case and chartered a plane to bring Navalny to Berlin. There doctors concluded that the symptoms — namely vomiting, sweating, respiratory distress, pinpoint pupils, foaming at the mouth and a slower than normal heart rate — were consistent with the inhibition of cholinesterase, an enzyme that normally degrades the neurotransmitter acetylcholine. This suggested possible exposure to a “nerve agent,” a chemical that interferes with the transmission of information from one nerve cell to another.
Such transmission involves the release of chemicals called neurotransmitters from a nerve ending followed by the migration of this substance across the tiny gap separating nerve cells, known as the synapse.
The neurotransmitter then stimulates an adjacent cell by fitting into a “receptor site” on its surface, very much as a key fits into a lock. Acetylcholine, the first neurotransmitter ever discovered (1921), stimulates muscle contraction, increases bodily secretions, pinpoints pupils and slows heart rate. Once acetylcholine has carried out its job of triggering a reaction in an adjacent cell, it is decomposed by an enzyme present in the synapse. Overstimulation is therefore prevented. It is this enzyme, acetylcholinesterase, that is inactivated by nerve agents.
Unless this activity is restored, overstimulation by acetylcholine will lead to convulsions, paralysis and respiratory failure.
Blood tests carried out by a special military lab in Germany confirmed the presence of a nerve agent in Navalny's system. Furthermore, the chemical belonged to a series developed by the Soviets in the 1970s named “Novichok,” which in Russian means “newcomer.” These newcomers were more potent than existing nerve agents and could be disseminated as powders and liquids.
The Russians had used one of these chemicals before in the celebrated case that has come to be known as the Salisbury Poisonings in the U.K. In 2018, Sergei Skripal, a former Russian spy who British intelligence managed to recruit as a double agent, and his daughter Yulia were poisoned with a Novichok agent that was applied to the doorknob of their home. A passerby found the Skripals incapacitated on a park bench and alerted police. When doctors in the hospital discovered Sergei's history, and considered both Skripals's symptoms, they began to suspect that a nerve agent had been used and initiated treatment.
Antidotes for poisoning by nerve agents have been extensively investigated. Since the 1930s, the first line of defence after exposure has been the injection of atropine, a drug derived from the belladonna plant. It is named after Atropos, the goddess in Greek mythology who decided when mortals would die by cutting their thread of life. Her sister Clotho spun the thread, and another, Lachesis, measured its length.
Atropine is known as an acetylcholine antagonist because it dislodges acetylcholine from receptor sites and thus reduces the risk of overstimulation. Atropine injection by itself is effective only for a short time since acetylcholinesterase remains inactivated by the nerve agent, so that the concentration of acetylcholine will keep increasing and eventually will overpower the protective effect of atropine. A second substance, called pralidoxime chloride, must be administered to release the nerve gas from the enzyme and destroy it. The patient may still be left with convulsions that can be treated with diazepam (Valium).
Exactly what else may have been involved in the treatment of the Skripals is not known, but both survived and were given new identities and are believed to be living in New Zealand.
Navalny is still in a German hospital and has received care similar to the Skripals and is expected to survive.
Dawn Sturgess was not as lucky. Soon after the Salisbury incident, she was poisoned when she sprayed what she thought was perfume on her wrist from a bottle her partner had found in a garbage bin. This was no perfume. The bottle had been made to look like perfume, but was actually a very sophisticated container that had been designed to sneak a Novichok nerve agent into the U.K by two Russians who were later caught on closed circuit TV and identified as secret agents. Sturgess was exposed to a much higher dose than the Skripals and the chemical was applied to a thinner, more permeable area of skin. Unfortunately, prompt medical treatment was unable to prevent her death. Sturgess's partner, Charlie Rowley, reportedly spilled some of the contents of the perfume bottle onto his hands, but immediately washed off the oily residue.
Of course, the Russians, in spite of overwhelming evidence, deny involvement in any of these poisonings and even deny the existence of Novichok agents. World leaders such as Germany's Angela Merkel and Britain's Boris Johnson have called for answers about the poisoning from Russian President Vladimir Putin but U.S. President Donald Trump has been silent on the subject. joe.schwarcz@mcgill.ca
Joe Schwarcz is director of Mcgill University's Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.