If glomerular filtration barrier has net negative charge...

Discussion in 'Step I' started by AlmostAnMD, 01.14.14.

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  1. AlmostAnMD

    AlmostAnMD 2+ Year Member

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    why is inulin freely filtered?

    Maybe I'm just tired, but this doesn't make any sense. In solution inulin has a lot of OH's floating around, wouldn't that leave an anionic charge when the H dissociates?

    I'm reading that anionic stuff impedes filtration of anions. Maybe my acid-base chemistry just needs work @_@
     
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  3. Dr joji

    Dr joji 2+ Year Member

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    Isn't it neutral?
     
  4. mcloaf

    mcloaf 2+ Year Member

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    It is supposedly negative, but at least according to Firecracker what effects, if any, this has on filtration is still contested in the literature.
     
  5. MudPhud20XX

    MudPhud20XX 2+ Year Member

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    Maybe I'm just tired, but this doesn't make any sense. In solution inulin has a lot of OH's floating around, wouldn't that leave an anionic charge when the H dissociates?

    I'm reading that anionic stuff impedes filtration of anions. Maybe my acid-base chemistry just needs work @_@


    --> You are right that inulin has lots of OH, but they aren't necessarily acidic protons so the OH groups won't be easily deprotonated. Thus, I don't those negative charges are strong enough to be repulsive.

    Here is a link that may help you: http://www.ncbi.nlm.nih.gov/pubmed/19585552

    Also keep in mind that some of the electrolytes such as chloride is also easily or freely filtered.
     
  6. RPedigo

    RPedigo Moderator Emeritus 10+ Year Member

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    It's not significantly negatively-charged. All the OH groups are attached to a carbon, therefore the H+ is not going to dissociate significantly. Think about ethanol EtOH, it doesn't become EtO- and H+ because the OH is attached to a carbon. When the OH is attached to a carbon with a double-bonded oxygen, making it a carboxylic acid, it is stabilized by resonance stabilization and therefore the H+ can dissociate. That would be like thinking glucose is negatively-charged because there's a bunch of OH groups -- there are a bunch of OH groups, but those H+ aren't going anywhere because the O- attached to a carbon isn't stable.
     

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