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Discussion on Need help in understanding the way sodium ion channels work
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Posted on Monday, Feb 11, 2002 - 9:28 pm:
I am looking for more indepth information on how the sodium Ion channels work in affected HYPP horses. I would like to know how the sodium and potassum work and why it causes muscle twitching and weakness in HYPP horses.
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Posted on Tuesday, Feb 12, 2002 - 12:37 pm:
Hello Candace,
It is believed that there is an increase in cell membrane sodium conductance do to the genetically defective subpopulation of the voltage dependent sodium channels.
They appear to fail to inactivate following a depolarization event or repeatedly open and close inappropriately. Depolarization (contraction) or other clinical and natural causes of increase in extracellular potassium further increase conductance in these defective channels resulting in more depolarizations and further moving of potassium out of the cell. These repeated depolarizations causes the fasiculations.
With repeated depolarization the cell may loose its excitability and flaccid paralysis occurs.
If you are trying to understand the working of the membrane potential in muscle cells and therby understand how HYPP works at the molecular level, the explanation of the working of sodium channels takes up dozens of pages in my medical physiology text and requires an intimate knowledge of chemistry and physics, particularly electricity. If you would like to peruse this any medical physiology text will explain this and I recommend Guyton.
DrO
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