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)

Inner medullary collecting duct function in ischemic acute renal failure: The purpose of this study was to determine the role of the medullary collecting duct in the increased urine sodium concentration, decreased urine osmolality, and altered potassium excretion with hyperkalemia which are characteristic of ischemic acute renal failure. Microcatheterization of the inner medullary collecting duct (0.1 to 5 mm from papillary tip) was carried out in rats 24 h after bilateral renal artery clamping for 45 min (n = 8) or sham-operated (n = 8). In ischemic acute renal failure (ARF), tubular fluid osmolality did not increase significantly along the inner medullary collecting duct (IMCD). Tubular fluid sodium concentration was similar to controls at the beginning of the IMCD but was significantly higher at the papillary tip. Tubular fluid to plasma potassium concentration ratio (TF/PK) increased to a greater extent along the IMCD in ischemic ARF than in controls. During acute KCl loading in two additional groups, tubular fluid potassium concentration and TF/PK were much lower at the beginning of the IMCD in ischemic ARF than in controls but increased similarly along the IMCD. In ischemic ARF, with or without KCl loading, renal tissue electrolytes showed reduced potassium concentration in the outer medullary region. The results indicate that impaired IMCD function contributes significantly to the increase in urine sodium concentration and the decrease in urine osmolality which are characteristic of ischemic acute renal failure. In ischemic ARF with mild hyperkalemia, an adaptive increase in K secretion occurred in the IMCD. Severe hyperkalemia and decreased potassium excretion during acute potassium loading in ischemic ARF were determined in more proximal nephron segments and were associated with decreased outer medullary tissue potassium, presumably due to tubular necrosis. Decreased outer medullary tissue potassium could contribute to hyperkalemia by diminishing K secretion in the pars rectae and descending limbs or in the cortical and outer medullary collecting ducts.
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PMID:Inner medullary collecting duct function in ischemic acute renal failure. 340 4

Acetazolamide, furosemide, chlorothiazide and amiloride are pharmacologic agents that act primarily in the proximal tubule, loop of Henle, early distal tubule and late distal tubule and collecting duct, respectively. These diuretic agents were used to evaluate the functional integrity of discrete segments of the nephron in the neonatal rat following treatment with a known nephrotoxicant. Six-day old rats were treated s.c. with the proximal tubule toxicant mercuric chloride (1 or 3.2 mg/kg) or saline. Twenty-four hours later, when evidence of mercury nephrotoxicity is detectable, creatinine clearance and the fractional excretion of water and various components of the filtrate were determined using a 2-hr clearance period immediately after injection of a diuretic. The effects of mercury (3.2 mg/kg) were consistent with its ability to cause acute renal failure and proximal tubular necrosis and also indicated an apparent disruption of the cycling of urea in the nephron. A decrease in the fractional excretion of water, combined sodium and potassium and total osmotic solutes indicated that the diuretic response to acetazolamide was markedly attenuated in the mercuric chloride-treated pups whereas the responses to furosemide, chlorothiazide and amiloride were not altered by mercury treatment. Results from this study illustrate the specificity of these diuretics as pharmacologic probes of mercuric chloride induced renal dysfunction and, therefore, support their usefulness as tools in the investigation of renal developmental toxicity.
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PMID:Pharmacologic probing of mercuric chloride-induced renal dysfunction in the neonatal rat. 361 27

This study was designed to compare the renal effects of atrial (A-type) natriuretic peptide (ANP) on control (saline-injected) rats and rats with non-oliguric acute renal failure induced by cisplatin. The results obtained here are summarized as follows: (1) In the metabolic cage study, cisplatin-treated rats showed increases in blood urea nitrogen and serum creatinine while creatinine clearance decreased to the lowest levels on day 4. A transient increase in urinary protein was observed at day 4. (2) ANP infusion significantly increased urine flow rate (UFR), creatinine clearance (CCr), fractional excretion rates of sodium (FENa) and chloride (FECl), and urinary phosphorus and magnesium (Mg) excretions in a dose-dependent manner without affecting renal plasma flow and fractional excretion rates of potassium and urea in cisplatin-treated rats. (3) Renal effects of ANP on UFR, CCr, FENa, FECl and excretion of Mg were more pronounced in cisplatin-treated rats compared to control rats although markedly blunted responses to ANP have been reported in nephrotic patients and nephrotic animals induced by adriamycin and aminonucleoside. (4) Histological examination showed extensive necrosis of the S3 segment of the proximal tubule located in the outer stripe of the outer medulla with minimal glomerular abnormalities in the kidney of cisplatin-treated rats. In conclusion, the main mechanism of the increased renal responses to ANP is considered to be due to an increased delivery of sodium, fluid and ANP itself to the inner medullary collecting duct which is the major renal site of action of ANP under the condition of acute proximal tubular necrosis by cisplatin.
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PMID:Renal responses to atrial natriuretic peptide (ANP) in rats with non-oliguric acute renal failure induced by cisplatin. 872 36

The mechanism by which cells sense extracellular tonicity and trigger the accumulation of protective organic osmolytes is poorly understood. It has been proposed that changes in cell volume following alteration of extracellular toncity are important initiators of signaling events that lead to osmolyte accumulation. Because the extracellular matrix receptors integrins are linked to the cytoskeleton and can transduce signals that alter cell behavior, we investigated the role of these receptors in the modulation of osmolyte accumulation in the kidney medulla under different osmotic conditions. We show that integrin alpha1-null mice have impaired ability to accumulate organic osmolytes in the inner medulla due to altered signaling and decreased induction of osmolyte transporters or aldose reductase gene transcription. Utilizing inner medullary collecting duct cells, we demonstrate that the lack of integrin alpha1beta1 results in an impaired ability to induce the tonicity enhancer-binding protein TonEBP under hypertonic conditions. Furthermore, under the same conditions, integrin alpha1-null cells show prolonged ERK1/2 phosphorylation and decreased inositol uptake compared with control cells. The reduction of inositol uptake is significantly reversed by treatment with the MEK inhibitor PD-98059. Finally, integrin alpha1-null mice develop morphological changes of early tubular necrosis and increased apoptosis of renal medullary cells following dehydration. Together, these results show that integrin alpha1beta1 is an important mediator of the compatible osmolyte response in the medulla of the mammalian kidney.
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PMID:Role of integrin alpha1beta1 in the regulation of renal medullary osmolyte concentration. 1610 35

The HNK-1 carbohydrate epitope is a 3-sulfo-glucuronyl residue attached to lactosamine structures on glycoproteins, proteoglycans, or glycolipids mostly expressed in the nervous system. Here, using monoclonal antibodies against the sulfated HNK-1 carbohydrate epitope, we first examined its distribution in developing and adult kidneys, then its expression in kidneys with tubular necrosis and renal neoplasms. This HNK-1 epitope was expressed in the human, rabbit, and rat, but not mouse kidney. It was detected within a subset of epithelial cells in the renal vesicle and in comma- and S-shaped bodies during early stages of nephrogenesis. In ureteral bud derivatives, the epitope was present transiently in the area where the collecting duct fused with the nephron. In the adult kidney, expression of the HNK-1 epitope became mainly restricted to the thin ascending loop of Henle where this epitope was carried by heparan- and chondro-proteoglycan. In pathological conditions, HNK-1 epitope expression increased dramatically in proximal epithelial tubule cells in kidneys with acute tubular necrosis. In tumors, the HNK-1 epitope was expressed in the epithelial component of nephroblastomas and in a subgroup of papillary renal cell carcinomas. These data suggest that molecules carrying the sulfated HNK-1 carbohydrate epitope may play an important role in critical stages of renal development and in the physiology of thin ascending loop of Henle.
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PMID:Sulfated HNK-1 epitope in developing and mature kidney: a new marker for thin ascending loop of Henle and tubular injury in acute tubular necrosis. 1640 97