About voltage-gated Na channels

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bbs_r
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About voltage-gated Na channels

Post by bbs_r » Wed Aug 10, 2005 4:29 pm

Hi, everyone. I just met a problem here.
According to the textbook "Neuroscience: Exploring the Brain 2nd Edition", under depolarization Voltage-gated Na channels open with a little delay about 1 msec. However, when I read through the topic, I found something very contradict:

In the voltage-gated K channel section, it saids "unlike Na gates, K gates do not open immediately upon depolarization, it takes about 1 msec..."

So, I suppose what it saids about sodium gates is "voltage-gated Na channels" and it just not making sense.

May anyone give me a hand please?

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Dr.Stein
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Post by Dr.Stein » Thu Aug 11, 2005 5:19 am

Read HERE. It provides a lot of info about your question ;)
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sdekivit
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Re: About voltage-gated Na channels

Post by sdekivit » Thu Aug 11, 2005 4:21 pm

bbs_r wrote:Hi, everyone. I just met a problem here.
According to the textbook "Neuroscience: Exploring the Brain 2nd Edition", under depolarization Voltage-gated Na channels open with a little delay about 1 msec. However, when I read through the topic, I found something very contradict:

In the voltage-gated K channel section, it saids "unlike Na gates, K gates do not open immediately upon depolarization, it takes about 1 msec..."

So, I suppose what it saids about sodium gates is "voltage-gated Na channels" and it just not making sense.

May anyone give me a hand please?


voltage-gated Na-channels open within about 1 ms. Voltage-gated K-channels about 3 ms i thought. First the VG Na-channels are opened and then inactivated. The VG K-channels are much slower and are not inactivated (they only close or open).

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MrMistery
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Post by MrMistery » Thu Aug 11, 2005 6:32 pm

What do you mean be "inactivated"? What is the difference between inactivated and closed?
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Post by sdekivit » Mon Aug 15, 2005 4:00 pm

a voltage gated Na-channel can be closed in two ways: by the activation gate and the inactivation gate.

At rest the activation gate is closed and thus the ionchannel is closed. When a stimulus enters Na(+) will depolarize the membrane and opens the activation gate so that the channel is open for Na-ions.

As the membrane potential rises, an inactivationprotein will, according to chance, close the channel, but not in a way the activation gate does. The inactivation gate is a protein that is bound to the channel protein with a tail. When the potential rises the protein will block the channel, while the activationgate is still open. We now call the channel protein inactivated instead of closed.

Thus closed means like a the door is closed to enter. Inactivated means the door is openend but the ways is blocked.

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Post by MrMistery » Mon Aug 15, 2005 8:22 pm

Valuable info... Thanks a bunch.. :D
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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