If glomerular filtration barrier has net negative charge...

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AlmostAnMD

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