Curare

We are continuing my 3 part series on neurotoxins.  Today we are discussing Curare.  Everyone needs to put on their big girl pants for this one because it gets technical.  All the way technical, which is the best kind of technical.

Today's Medical Topic:  Curare:  What is it, how does it work, and why is my tongue numb?

Off the Top of My Head:   An almost mythical poison the actuality of what curare is has become quite skewed throughout history.  In novels like Sherlock Holmes it is the mysterious poison created by witch doctors in jungle tribes and used with devastating accuracy in blow guns.  But how much of this is true and how much is myth?  Let's find out.

My Research Today:  "Curare" used by South American tribes is actually a strange syrupy concoction of plants, roots, toxins, and venoms assembled from various sources.  These items are crushed, cooked, and mixed to make a black sticky poison that tribal hunters use on the tips of their arrows.

They aren't wearing much but I feel
like 90% of it is still frivolous.

Regardless of what else is mixed into this concoction the active ingredient of curare is D-tubocurarine the product of a root of a vine called Chondroendron tomentosum.  D-tubocurarine is a non-depolarizing muscle relaxant drug (NDMRD).  Many NDMRD's have been developed from D-tubocurarine but let's look at how this class of drug works.

The name gives you a hint as to how it works, what with the non-depolarizing in the title, but if you look closer you will see it is more complicated than that.  NDRMD's diffuse through blood vessels into the synaptic cleft of motor neuromuscular junctions.  There NDMRD's compete with acetylcholine (ACh) molecules released into the synaptic cleft and then bind to the ACh receptors on the synaptic endplate.  This blocks the ACh from binding and therefore prevents the initiation of the depolarization process of muscle contraction.

NDMRD's also act on presynaptic receptors which interfere with the entry of calcium ions into the axon terminal which in turn doesn't allow as much ACh to be released magnifying the effect of the NDRMD.

It is importanant to note the NDMRD's must be injected into the bloodstream and cannot work if they are simply ingested by other means.  NDMRD's follow a simillar paralyzation pattern as Botulism does. Starting from top to bottom.  You need a fairly significant dose for NDMRD's to affect your chest wall muscles and diaphragm.

NDMRD's are a water-soluble, polar molecules which make them unable to break the blood-brain barrier.  For this reson NDMRD's do not effect your autonomous nervous system so your heart will continue to beat.  This makes NDMRD's ideal for sedated patients on ventilators.

That is all for now.  Tomorrow we work on Saxitoxin which is somewhat difficult to find data on..

Send questions or comments to dudaday@gmail.com

Disclaimer:  I am not a health care provider, any information presented in this blog should not be considered advice it is mearly an outlet to slake my curiosity.  You should always consult your primary medical provider for any concerns or illness.  Unlike Tylenol, I am not approved by the FDA or American Medical Association to treat or provide relief for any ailment.