Local Anesthestics

[Dryacku]

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This maybe a stupid last minute question, but different sources state different things.

Which nerve fibers are the most sensitivity to LA?

thanks

 

[Planktonmd]

This maybe a stupid last minute question, but different sources state different things.

Which nerve fibers are the most sensitivity to LA?

thanks

The larger faster nerve fibers are more sensitive so:
A more sensitive than B more sensitive than C

 

[aredoubleyou]

The larger faster nerve fibers are more sensitive so:
A more sensitive than B more sensitive than C

I think thats wrong. Its very confusing. The smaller, the more sensitive. The more mylenation, the more resistant. The more active the nerve fires, the more sensitive.

B fibers are probably the most sensitive. Followed by C, and A fibers are the most resistant.

 

[countingdays]

I think thats wrong. Its very confusing. The smaller, the more sensitive. The more mylenation, the more resistant. The more active the nerve fires, the more sensitive.

B fibers are probably the most sensitive. Followed by C, and A fibers are the most resistant.

Miller says
small myelinated axons are the most susceptible
then large myelinated fibers
the least susceptible are the small, nonmyelinated C fibers.
"The generalized notion that local anesthetics block the smallest fibers first or most is clearly wrong."

 

[leviathan]

Two things controlling affinity are diameter and myelination. Smaller diameter are more sensitive, and more myelination are more sensitive. The former factor plays a more prominent role. That's why A-delta are the first to get affected, followed by A-beta etc etc.

 

[Mofeen]

This maybe a stupid last minute question, but different sources state different things.

Which nerve fibers are the most sensitivity to LA?

thanks

Try hukt on fonix.

 

[Planktonmd]

I think thats wrong. Its very confusing. The smaller, the more sensitive. The more mylenation, the more resistant. The more active the nerve fires, the more sensitive.

B fibers are probably the most sensitive. Followed by C, and A fibers are the most resistant.

Look at this:
http://www.ncbi.nlm.nih.gov/pubmed/7457962

 

[aredoubleyou]

Its very confusing. I looked up in Margan Mikhail and it says "small diameter and lack of myelin enhance sensitivity to local anesthetics. Thus, in spinal nerves sensitivity to local anesthetics is autonomic> sensory > motor."

Guess I'm wrong...but I'm also not making things up either.