Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

These results are consistent with a model for renal tubular transport of urate in which there is reabsorption of both filtered and secreted urate. Urate secretion greatly exceeds total urate excretion, and most secreted urate is reabsorbed. At least a portion of urate reabsorption occurs at a site distal to or coextensive with the urate secretory site. There appear to be at least two distinct reabsorptive mechanisms for urate. The results of the flow rate and vasopressin studies are consistent with the hypothesis that urate reabsorption occurs in both the distal and the proximal tubule in man. The distal reabsorptive site appears to be quite small. It may be passive since it does not appear to be inhibited by uricosuric drugs. This reabsorptive site may account for less than 15% of total urate reabsorption. Both volume expansion and probenecid may inhibit urate absorption only in the proximal tubule. Thus reabsorption in the proximal tubule coud account for more than 90% of total urate reabsorption. Reabsorption at the postulated collecting duct reabsorptive site appears to be too small in magnitude to account for all reabsorptions of secreted urate. This could be explained if the reabsorptive site in the proximal tubule is coextensive with or distal to the secretory site. Alternatively, there might be two reabsorptive sites in the proximal tubule: a presecretory site accounting for the reabsorption of most filtered urate, and a site either coextensive or distal to the secretory site accounting for a major component of reabsorption of secreted urate. Finally urate reabsorption would also take place in the collecting duct, perhaps at a passive, flow-dependent site.
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PMID:Postsecretory reabsorption of urate in man. 120 Nov 24

Attachment of microcrystals to cellular membranes may be an important component in the pathophysiology of urolithiasis. This study characterizes the concentration-dependent binding of uric acid crystals to rat renal inner medullary collecting duct cells in primary culture. Collecting duct cell cultures grew as monolayers with interspersed aggregates of rounded cells. Cultures were incubated with 14C-uric acid crystals, and the crystals that bound were quantitated by adherent radioactivity. Uric acid crystal adherence demonstrated concentration dependent saturation with a 1/alpha value (maximum micrograms of crystals adhering to 1 cm2 of binding area) of 645 micrograms/cm2. The beta values (fraction of cross-sectional area which bound crystals) of uric acid (mean = 0.15) and calcium oxalate monohydrate (mean = 0.13) crystals did not differ significantly. Uric acid crystal binding was inhibited by pre-bound calcium oxalate monohydrate crystals in a concentration dependent manner. These data suggest that uric acid and calcium oxalate crystals exhibit similar binding patterns to rat renal inner medullary collecting duct cells in primary culture.
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PMID:Uric acid crystal binding to renal inner medullary collecting duct cells in primary culture. 210 62

1. While it is believed that the mammalian distal nephron is not involved in uric acid transport, this has not been directly evaluated. Nevertheless, some studies are consistent with significant distal nephron transport. 2. As uric acid transport in man may be similar to the rat, undirectional uric acid permeability was evaluated by perfusion of the isolated rat papillary collecting duct. 3. Uric acid permeability was 0.61 +/- 0.04 micron/s, which was similar to sodium permeability (0.66 +/- 0.05 micron/s) but was less than chloride permeability (0.93 +/- 0.07 micron/s) and markedly less than water permeability (4.81 +/- 0.21 micron/s). Uric acid permeability was not changed following the addition of a maximal antidiuretic concentration of arginine vasopressin (200 microU/mL), nor was it changed by altering the uric acid concentration in the perfusate and bath. 4. These results demonstrate that the papillary collecting duct is permeable to uric acid. The coefficient of transport is sufficiently low and insensitive to arginine vasopressin and uric acid concentrations to suggest that any transport that occurs is probably passive and only of minor physiological significance.
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PMID:Uric acid permeability coefficient in the rat papillary collecting duct. 931 80

Classically, urate nephropathy has been postulated to cause kidney disease by depositing intraluminal crystal in the collecting duct. Recently, molecular mechanisms of inflammasome have been investigated. Urate-induced inflammasome pathway is comprised of urate crystal uptake into intracellular lysosomes and subsequent lysosomal rupture with mitochondrial reactive oxygen species (ROS) production, which activates the NLRP3 inflammasome. Against the lysosomal rupture and mitochondrial ROS production, autophagy acts to protect proximal tubular cells by isolating them from expanding the inflammation. In addition, increased cellular urate, directly or indirectly via xanthine oxidase-induced oxidative stress, may be associated with inflammasome. In addition to the traditional therapy against hyperuricemia, management of urate-induced inflammasome or augmentation of autophagy may offer the new effective therapies.
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PMID:Hyperuricemia-induced inflammasome and kidney diseases. 2582 26