Skido asked in Science & MathematicsMedicine · 1 decade ago

what prevents ach from accumalating in the neuromuscular junction and causing a sustained contraction?

Thanks...I'm studying for an exam now and need some extra clarification...my book isn't really doing a good job at explaining things.

Also,

Succinylcholine behaves as a depolarizing agent that inhibits repolarization of the nerve. Therefore, no more ACh is released until the drug is cleared. What is another ste within the neuromuscular junction that might be affected to prevent muscle contraction?

A hint would be curare behaves via this mechanism...

Thanks!

2 Answers

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  • RM
    Lv 6
    1 decade ago
    Best Answer

    what prevents ach from accumalating in the neuromuscular junction and causing a sustained contraction?

    - acetylcholinesterase

    Succinylcholine behaves as a depolarizing agent that inhibits repolarization of the nerve. Therefore, no more ACh is released until the drug is cleared. What is another ste within the neuromuscular junction that might be affected to prevent muscle contraction?

    - actually, more ACh can be released but it doesn't help because the succinylcholine is keeping the receptor depolarized. Activation ACh receptors cause release of intracellular Ca++ in the muscle cells upon initial depolariztion (which is what allows activation of the muscle fiber contraction). However, if it stays depolarized no more Ca++ is released and more ACh does not have an effect (assuming full blockade was achieved).

    A hint would be curare behaves via this mechanism...

    - Another way to prevent muscle contraction is to prevent the receptor from getting activated in the first place. These compounds block the receptor and don't allow ACh to bind in the first place. In clinical practice these are all "competitive" nonpolarizing agents and therefore adding more ACh may allow greater contraction depending on the concentration present. These agents are relatives of curare which is one of many competitive nondepolarizing neuromuscular blocking agents.

  • Anonymous
    1 decade ago

    did you

    Source(s): google
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