States of altered consciousness have long fascinated philosophers, junkies, and priestesses, yet the complete loss of consciousness is not considered to be either rarified or impressive.
By way of anesthesia, nearly 250 million people each year “go under” during one or another medical procedure. What is remarkable in this is that these everyday drugs remain utterly mysterious to the scientists who develop and use them.
“We still don’t know how they work,” Dr. Roderic G. Eckenhoff, a professor in the Department of Anesthesiology and Critical Care at the University of Pennsylvania, told Medical Daily.
Among the most original hypotheses in currency today is that of Dr. Luca Turin of the Alexander Fleming Research Center in Athens, Greece. Rather than through more conventional pharmacological mechanisms, general anesthetics “perturb electron currents in cells” and so extinguish consciousness by subtly changing the electronic state of proteins, Turin believes. His theory reaches far beyond the two more common though still quite controversial schools of thought.
On one side of the divide, scientists believe anesthetics work by interacting with a few key ion channels that regulate synaptic transmission and membrane potentials in the brain and spinal cord. On the other side, researchers including Eckenhoff, theorize anesthetics interact with dozens, maybe even hundreds of molecular targets to produce their effects.
The authors of “Consciousness and Anesthesia,” which appeared in Science in 2009, suggest that agents of anesthesia target, either directly or indirectly, a “posterior lateral corticothalamic complex centered around the inferior parietal lobe, and perhaps a medial cortical core.”
Unconsciousness results, then, when anesthetics “deactivate” the posterior corticothalamic complex, yet also because they produce what the authors describe as “a functional disconnection” between subregions of this complex.
“Anesthetics also tend to have a certain physical-chemical profile,” Eckenhoff explains, noting how they are, for the most part, uniformly small, uncharged molecules. While the blood brain barrier is able to filter out other drugs, the unique qualities of an anesthetic molecule allow it to slip past this guard. “It’s like the blood-brain barrier doesn’t even exist,” he says.
This much, then, may be common knowledge today, but there were many years when even less was known about these drugs.
Western historians point to the 18th century as the beginning of the modern age of anesthesia. However, since recorded time, scientists have been experimenting with plants and other herbal remedies to produce the necessary effects of immobilization and loss of consciousness. While various ancient civilizations discovered one form or another, the Chinese doctor Bian Que notably created his own toxic drink for use during surgical procedures as far back as 300 B.C.
In Europe, an Italian physician, Theodoric of Lucca, reportedly soaked sponges in opium and mandragora to relieve the pain of patients undergoing operations during the 13th Century. And less than 200 years later, Paracelsus, the Swiss German physician and Renaissance man who found the discipline of Toxicology, began using ether on animals.
Still, a safe, effective, and most importantly consistent anesthesia did not emerge for some years. According to Eckenhoff, who is no stranger to the lab, “Empiricism and trial and error has characterized most of anesthetic discovery,” and this is evidenced in most accounts.
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