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9 Cards in this Set
- Front
- Back
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What are Aquaporins?
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Research on mice, rats and humans indicates that rapid diffusion of water across cell membranes depends on water channels made up of proteins called Aquaporins.
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How many acquaporins have been identified?
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Four acquaporins, 1, 2, 5 and 9 have been found in humans, and others have been found in rats. Most are found in the kidneys.
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Where has aquaporin 9 been found?
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It has been found in human leukocytes, liver, lung and spleen, and aquaporin 5 is found in human lacrimal glands.
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Describe aquaporin 1?
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It is localized in the proximal tubules. When it is destroyed in mice, proximal tubule water permeability is reduced 80%, and plasma osmolality increases to 500mosm/kg when the mice are subjected to dehydration, despite other aquaporins being intact.
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Describe aquaporin 1?
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It is localized in the proximal tubules. When it is destroyed in mice, proximal tubule water permeability is reduced 80%, and plasma osmolality increases to 500mosm/kg when the mice are subjected to dehydration, despite other aquaporins being intact.
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What is Bartter's syndrome?
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It is caused by defective transport in the thick ascending limb. It is characterized by chronic Na+ loss in the urine, with resultant hypovolemia causing stimulation of renin and aldosterone secretion without hypertension, plus hyperkalemia and alkalosis.
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What is the pathogenesis of Bartter's syndrome?
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It can be caused by loss of function mutations in the gene for any of four key proteins: the Na+-K+-2Cl- cotransporter, the ROMK K+ channel, the CIC-Kb Cl- channel, or barttin.
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What is Barttin?
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It is a recently described integral membrane protein that is necessary for the normal function of CIC-Kb Cl- channels.
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The stria vascularis in the inner ear is responsible for maintaining the high K+ concentration in the scala media that is essential for normal hearing. TRUE/FALSE
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TRUE. It contains both CIC-Kb and CIC-Ka Cl- channels.
Bartters syndrome associated with mutated CIC-Kb channels is not associated with deafness because the Clc-Ka channels can carry the load. However, both, types of Cl- channels are barttin dependent, so patients with Bartters syndrome due to mutated barttin are also deaf. |
