8/14/2019 Mystery of Anesthetic Mechanism May Be Solved
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Mystery of anesthetic mechanism may be solved
by MIKE MARTIN, UPI Science Correspondent
NEW YORK, Feb. 15, (UPI) -- Although more than 150 years have
past since the discovery ofgeneral anesthetics, how they precisely
work remains a mystery. Biophysicists at the Mount SinaiMedical
Center in New York may be close to solving this riddle.
Huping Hu and Maoxin Wu have proposed a mechanism that may lead
to better, saferanesthetics, a revolution in the treatment of pain,
and a more complete understanding of theeffects of alcohol on brain
function. General (as opposed to local) anesthetics affect a
variety ofneurotransmitter receptors.
However, a universally accepted mechanism of anesthesia remains
elusive. Presently, two schoolsof thought exist. The "lipid theory"
proposes that anesthetics interact directly with cellmembranes that
are involved in brain functions. The "protein theory" suggests that
anestheticsdirectly interact with cell proteins such as the ion
channels and receptors that are involved inneurotransmission.
Neither concept is supported by direct experimental evidence.
Wu and Hu, on the other hand, speculate that general anesthetics
perturb the pathways of oxygen,the most essential component of
brain function, in both cellular membranes and cellular proteins.In
essence, their mechanism holds that anesthetics act as barriers to
oxygen transport in bothmembranes and proteins, reducing oxygen
availability to the brain. When the brain detectsoxygen
deprivation, or hypoxia, it immediately reduces its workload. Part
of this workload issensing pain. Wu and Hu claim that anesthesia,
then, is a byproduct of the brain's own self-preservation
mechanism.
Wu and Hu predict that better anesthetics can be formulated that
more effectively block oxygenpathways by enhancing their ability to
be absorbed by the fatty membranes that serve as oxygen
gateways. Anesthetics with shorter hydrocarbon chains would be
more effective than anestheticswith longer-chain hydrocarbons
because the membranes that control oxygen uptake in the brainmore
easily absorb them. Additionally, clinicians may use the proposed
mechanism to bettercontrol and predict side effects.
"Anesthesiologists need consider direct monitoring of
intracellular or even sub-cellular oxygenconcentrations during
anesthetic procedures since our hypothesis suggests hypoxia or
hypoxia-mimicking situations at the sub-cellular or molecular
level," Dr. Hu told UPI. Too much oxygendeprivation at this level
can lead to tissue death, he said.
Dr. Judith Tharp, a chief clinician with the Federal Bureau of
Prisons, expressed fascination withthe results. "There's no
question that a mechanism such as the one proposed by Drs. Wu and
Hu
could result in the formulation of better anesthetics, simply by
defining their exact targets moreprecisely," she said. "It is
true--we still don't know exactly what we are aiming for with
generalanesthesia."
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11/24/2009http://www.quantumbrain.org/anesthesia.html
