Cell types in the enteric nervous system !

Lars Thomsen lthomsen at aix1.danadata.dk
Sun Aug 27 07:57:23 EST 1995


I would like comment to the following differences of classification :

The enteric nervous system controlling the gastrointestinal tract
contains different types of neurones.

According to Bornstein et al, 1994 :
--------------------------------------------------
AH neurone. 
Has a longlasting afterhyperpolarization following a actionpotential.
Shows rarely cholinergic fast EPSPs (guinapig small intestine)

S neurone
No longlasting afterhyperpolarization
--------------------------------------------------


According to Wood 1994

S/Type 1
high input resistance
low resting mebrane potential (depolarized)
fires several spikes during a period of depolarization.
anodal-break excitation
TTX sensitive action potentials

AH/Type 2
low input resistance
high resting membrane potential (hyperpolarized)
fires only in beginning of depolarization period
longlasting afterhyperpolarization
TTX resitant spikes
no anodal-break excitation

Type 3
No spikes
prominent fast EPSPs
Application of cAMP makes this cell type to change to a AH/Type2 (!!)


Type 4
Intermediate between Type1 and Type2
__________________________________________

I would like to know if their exists well documented reports from
other systems where it has been shown that one cell type can turn into
another type within the time of an electrophysiological recording (1-4
hours).

I would also like to know if it is general accepted that a neurone can
exist in a state where it is inexcitable, meaning that a spike not can
be evoked even by increasing amount of injected current.







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