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* TO dolly123,maleki,amith,airmax,BEN...and for ALL
 #134247  
  aloo2 - 10/31/06 13:18
 
  what's the most accurate ANS??
Mysthenia Gravis:
we know that in MG,
auto antibodies formation against ACH receptor.......but my Q is what's the actual consequence???

A---decrese the Ach-Receptors(#) in presynaptic membrane
B---decrese the Ach -Receptors (#)in post synaptic membrane
c----decrese the ACH level in synaptic juction....


 
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537714
  dolly123 - 10/31/06 13:28
 
  as far as i know:
1. the autoantibodies are directed most commonly against the acetylcholine receptor (nicotinic type), the receptor in the motor end plate for the neurotransmitter acetylcholine that stimulates muscular contraction.

2.Some forms of the antibody impair the ability of acetylcholine to bind to receptors.

3.Others lead to the destruction of receptors, either by complement fixation or by inducing the muscle cell to eliminate the receptors through endocytosis.


as an explanation of (1) we see the effect by cholinesterase inhibitors, such as neostigmine and pyridostigmine. These slow the natural enzyme cholinesterase that degrades acetylcholine in the motor end plate; the neurotransmitter is therefore around longer to stimulate its receptor
 
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537788
  airmax - 10/31/06 14:00
 
  yap agree with dolly....  
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537820
  ben - 10/31/06 14:19
 
  B---decrese the Ach -Receptors (#)in post synaptic membrane


In MG you have Ab's that bind to post synaptic membrane of the motor endplates (neuromuscular junction) and thus interfering with binding of ACh. B/c Ab's bind to receptors they become desensitized which leads to a decr in the amount of receptors on the post synaptic membrane.

Sensitization or Desensitization of receptors means that if you overstimulate the receptors they become very sensitive to even very small amounts of hormones whereas when you desensitize a receptor they sort of regress back into to the membrane (involute) thus leaving less amounts of receptors on the membrane, and that is what you see with MG


The drugs that dolly talks about inhibt ACH Esterase, which is responsible for degrading ACh once it has done its job. By inhibintg the enzyme ACh stays around longer, they also bind on receptors that are free and therfore longer action will lessen the effects in MG.
 
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537827
  ben - 10/31/06 14:21
 
  pls ask if any confusion on my explanation  
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537838
  ben - 10/31/06 14:32
 
  in addition aloo, the same concept also is seen w/ insulin resistance. In both disease the receptors become desensitized b/c of continuous binding. Not sure if their decrease is realted to them involuting back into the membrane or if they burn out.  
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* Re:TO dolly123,maleki,amith,airmax,BEN...and for A
#537921
  aloo2 - 10/31/06 15:20
 
  dolly and BEN
thank you soooo much.
BEN i don't have any confusion with UR and dolly's explanation...hanks again........
PS----board question :-)))))))
 
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