Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0032617 (polyuria)
 3,056 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lithium (Li) treatment is often associated with nephrogenic diabetes insipidus (NDI). The changes in whole kidney expression of aquaporin-1 (AQP1), -2, and -3 as well as Na-K-ATPase, type 3 Na/H exchanger (NHE3), type 2 Na-Pi cotransporter (NaPi-2), type 1 bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1), and thiazide-sensitive Na-Cl cotransporter (TSC) were examined in rats treated with Li orally for 4 wk: protocol 1, high doses of Li (high Na(+) intake), and protocol 2, low doses of Li (identical food and normal Na(+) intake in Li-treated and control rats). Both protocols resulted in severe polyuria. Semiquantitative immunoblotting revealed that whole kidney abundance of AQP2 was dramatically reduced to 6% (protocol 1) and 27% (protocol 2) of control levels. In contrast, the abundance of AQP1 was not decreased. Immunoelectron microscopy confirmed the dramatic downregulation of AQP2 and AQP3, whereas AQP4 labeling was not reduced. Li-treated rats had a marked increase in urinary Na(+) excretion in both protocols. However, the expression of several major Na(+) transporters in the proximal tubule, loop of Henle, and distal convoluted tubule was unchanged in protocol 2, whereas in protocol 1 significantly increased NHE3 and BSC-1 expression or reduced NaPi-2 expression was associated with chronic Li treatment. In conclusion, severe downregulation of AQP2 and AQP3 appears to be important for the development of Li-induced polyuria. In contrast, the increased or unchanged expression of NHE3, BSC-1, Na-K-ATPase, and TSC indicates that these Na(+) transporters do not participate in the development of Li-induced polyuria.
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PMID:Altered expression of renal AQPs and Na(+) transporters in rats with lithium-induced NDI. 1096 35

Diabetes mellitus (DM) is associated with osmotic diuresis and natriuresis. At day 15, rats with DM induced by streptozotocin (n = 13) had severe hyperglycemia (27.1 +/- 0.4 vs. 4.7 +/- 0.1 mM in controls) and had a fivefold increase in water intake (123 +/- 5 vs. 25 +/- 2 ml/day) and urine output. Semiquantitative immunoblotting revealed a significant increase in inner medullary AQP2 (201 +/- 12% of control rats, P < 0.05) and phosphorylated (Ser(256)) AQP2 (p-AQP2) abundance (299 +/- 32%) in DM rats. Also, the abundance of inner medullary AQP3 was markedly increased to 171 +/- 19% of control levels (100 +/- 4%, n = 7, P < 0.05). In contrast, the abundance of whole kidney AQP1 (90 +/- 3%) and inner medullary AQP4 (121 +/- 16%) was unchanged in rats with DM. Immunoelectron microscopy further revealed an increased labeling of AQP2 in the apical plasma membrane of collecting duct principal cells (with less labeling in the intracellular vesicles) of DM rats, indicating enhanced trafficking of AQP2 to the apical plasma membrane. There was a marked increase in urinary sodium excretion in DM. Only Na(+)/H(+) exchanger NHE3 was downregulated (67 +/- 10 vs. 100 +/- 11%) whereas there were no significant changes in abundance of type 2 Na-phosphate cotransporter (128 +/- 6 vs. 100 +/- 10%); the Na-K-2Cl cotransporter (125 +/- 19 vs. 100 +/- 10%); the thiazide-sensitive Na-Cl cotransporter (121 +/- 9 vs. 100 +/- 10%); the alpha(1)-subunit of the Na-K-ATPase (106 +/- 7 vs. 100 +/- 5%); and the proximal tubule Na-HCO(3) cotransporter (98 +/- 16 vs. 100 +/- 7%). In conclusion, DM rats had an increased AQP2, p-AQP2, and AQP3 abundance as well as high AQP2 labeling of the apical plasma membrane, which is likely to represent a vasopressin-mediated compensatory increase in response to the severe polyuria. In contrast, there were no major changes in the abundance of AQP1, AQP4, and several major proximal and distal tubule Na(+) transporters except NHE3 downregulation, which may participate in the increased sodium excretion.
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PMID:Compensatory increase in AQP2, p-AQP2, and AQP3 expression in rats with diabetes mellitus. 1124 63

Chronic hypercalcemia (HC) is accompanied by urinary concentration defects, and functional studies indicate defects in the thick ascending limb (TAL). We hypothesize that dysregulation of renal sodium transporters may play an important role in this. Vitamin D-induced HC in rats resulted in polyuria, natriuresis, and phosphaturia. Immunoblotting revealed a marked reduction in the abundance of rat type 1 bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1) in inner stripe of the outer medullary (ISOM; 36 +/- 5%) and whole kidney (51 +/- 11%) in HC. Consistent with this finding, immunocytochemistry and immunoelectron microscopy demonstrated reduced BSC-1 labeling of the apical plasma membrane. Immunoblotting and immunohistochemical labeling of the K channel Kir 1.1 (ROMK) was also reduced in HC. In contrast, there were no reductions in the expression of Na/H exchanger (NHE)3 and Na,K-ATPase in ISOM. The abundance of the proximal tubule type II Na-P(i) cotransporter (NaPi-2) (but not Na,K-ATPase and NHE3) was significantly reduced (25 +/- 4%), consistent with a dramatic increase in urinary phosphate excretion. In conclusion, 1) the reduced abundance of BSC-1 and ROMK in TAL is likely to play a major role in the urinary concentration defects associated with HC and 2) the reduced abundance of NaPi-2 is likely to play a role in the increased urinary phosphate excretion.
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PMID:Reduced expression of Na-K-2Cl cotransporter in medullary TAL in vitamin D-induced hypercalcemia in rats. 1173 10

Nephrotoxicity in humans and experimental animals due to chronic exposure to cadmium (Cd) is manifested by defects in the reabsorptive and secretory functions of proximal tubules (PT). The main symptoms of Cd nephrotoxicity, including polyuria, phosphaturia, aminoaciduria, glucosuria, and proteinuria, suggest that various brush-border membrane (BBM) transporters are the main targets of Cd. Specific transporters may be either directly inhibited by Cd or lost from the BBM after Cd treatment, or both. We have recently proposed that Cd may impair the vesicle-dependent recycling of BBM transporters by inhibiting vacuolar H+-ATPase (V-ATPase) activity and endocytosis in PT cells (Herak-Kramberger CM, Sabolic I, and Brown D. Kidney Int 53: 1713-1726, 1998). The mechanism underlying the Cd effect was further explored in an in vivo model of experimental Cd nephrotoxicity induced by Cd-metallothionein (Cd-MT; 0.4 mg Cd/kg body mass; a single dose sc) in rats. The time-dependent redistribution of various BBM transporters was examined in this model by fluorescence and gold-labeling immunocytochemistry on tissue sections and by immunoblotting of isolated renal cortical BBM. In PT cells of Cd-MT-treated rats, we observed 1) shortening and loss of microvilli; 2) time-dependent loss of megalin, V-ATPase, aquaporin-1 (AQP1), and type 3 Na+/H+ exchanger (NHE3) from the BBM; 3) redistribution of these transporters into vesicles that were randomly scattered throughout the cell cytoplasm; and 4) redistribution of NHE3, but not megalin, into the basolateral plasma membrane. The internalization of BBM transporters was accompanied by fragmentation and loss of microtubules and by an increased abundance of alpha-tubulin monomers in PT cells. Transporter redistribution was detectable as early as 1 h after Cd-MT treatment and increased in magnitude over the next 12 h. We conclude that the early mechanism of Cd toxicity in PT cells may include a colchicine-like depolymerization of microtubules and impaired vesicle-dependent recycling of various BBM proteins. These processes may lead to a time-dependent loss of cell membrane components, resulting in reabsorptive and secretory defects that occur in Cd-induced nephrotoxicity.
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PMID:Cd-MT causes endocytosis of brush-border transporters in rat renal proximal tubules. 1242 37

Urinary tract obstruction impairs urinary concentrating capacity and reabsorption of sodium. To clarify the molecular mechanisms of these defects, expression levels of renal sodium transporters were examined in rats with 24-h bilateral ureteral obstruction (BUO) or at day 3 or 14 after release of BUO (BUO-R). BUO resulted in downregulation of type 3 Na+/H+ exchanger (NHE3) to 41 +/- 14%, type 2 Na-Pi cotransporter (NaPi-2) to 26 +/- 6%, Na-K-ATPase to 67 +/- 8%, type 1 bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1) to 20 +/- 7%, and thiazide-sensitive cotransporter (TSC) to 37 +/- 9%. Immunocytochemistry confirmed downregulation of NHE3, NaPi-2, Na-K-ATPase, BSC-1, and TSC. Consistent with this downregulation, BUO-R was associated with polyuria, reduced urinary osmolality, and increased urinary sodium and phosphate excretion. BUO-R for 3 days caused a persistant downregulation of NHE3 to 53 +/- 10%, NaPi-2 to 57 +/- 9%, Na-K-ATPase to 62 +/- 8%, BSC-1 to 50 +/- 12%, and TSC to 56 +/- 16%, which was associated with a marked reduction in the net renal reabsorption of sodium (616 +/- 54 vs. 944 +/- 24 micromol x min-1 x kg-1; P < 0.05) and phosphate (6.3 +/- 0.9 vs. 13.1 +/- 0.4 micromol x min-1. kg-1; P < 0.05) demonstrating a defect in renal sodium and phosphate reabsorption capacity. Moreover, downregulation of Na-K-ATPase and TSC persisted in BUO-R for 14 days, whereas NHE3, NaPi-2, and BSC-1 were normalized to control levels. In conclusion, downregulation of renal Na transporters in rats with BUO and release of BUO are likely to contribute to the associated urinary concentrating defect, increased urinary sodium excretion, and postobstructive polyuria.
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PMID:Altered expression of major renal Na transporters in rats with bilateral ureteral obstruction and release of obstruction. 1286 55

The apical Na+-H+ exchanger NHE3 plays an important role in fluid reabsorption in the proximal tubule. However, whether its deletion alters the salt and water transport in the distal nephron remains unknown. To answer these questions, wild-type (Nhe3+/+) and NHE3 null mice (Nhe3-/-) were placed in metabolic cages and their water balance and urine osmolality were examined. Nhe3-/- mice demonstrated a significant polydipsia (P < 0.03) and polyuria (P < 0.04), with a lower urine osmolality (P < 0.003) as compared to Nhe3+/+ mice. Northern hybridization and immunoblotting studies indicated that the mRNA expression and protein abundance of the collecting duct (CD) water channel AQP2 decreased by 52 % (P < 0.0003) and 73 % (P < 0.003) in the cortex, and by 53 % and 54 % (P < 0.002) in the inner medulla (IM) of Nhe3-/- vs. Nhe3+/+ mice. The expression of AQP2 in the outer medulla (OM) remained unchanged. Further, the mRNA expression and protein abundance of the medullary thick ascending limb (mTAL) apical Na+-K+-2Cl- cotransporter (NKCC2) decreased by 52 % (P < 0.02) and 44 % (P < 0.01), respectively, in the OM of Nhe3-/- vs. Nhe3+/+ mice. The circulating plasma levels of vasopressin as well as the mRNA expression of vasopressin prohormone were significantly increased in Nhe3-/- vs. Nhe3+/+ mice (P < 0.05). Studies in mice treated with acetazolamide indicated that increased bicarbonate and fluid delivery to distal nephron did not alter the expression of NKCC2 in mTAL and decreased AQP2 protein only in OM but not in the cortex or IM. In conclusion, mice lacking the apical NHE3 have impairment in their water balance and urine osmolality, which correlates with the downregulation of AQP2 expression. These defects occur despite increased circulating levels of vasopressin. We propose that an ADH-independent mechanism is responsible for the downregulation of AQP2 and the resulting polyuria in NHE3 null mice.
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PMID:Downregulation of renal AQP2 water channel and NKCC2 in mice lacking the apical Na+-H+ exchanger NHE3. 1450 Jul 65

The purpose of this study was to evaluate whether the natriuresis and polyuria seen in parathyroid hormone (PTH)-induced hypercalcemia are associated with dysregulation of renal Na transporters. Rats were infused with three different doses of human PTH [PTH (1-34); 7.5, 10, and 15 microg.kg(-1).day(-1) s.c.] or vehicle for 48 h using osmotic minipumps. The rats treated with PTH developed significant hypercalcemia (plasma total calcium levels: 2.71 +/- 0.03, 2.77 +/- 0.02, and 3.42 +/- 0.06 mmol/l, respectively, P < 0.05 compared with corresponding controls). The rats with severe hypercalcemia induced by high-dose PTH developed a decreased glomerular filtration rate (GFR), increased urine output, reduced urinary osmolality, increased urinary Na excretion, and fractional excretion of Na. This was associated with downregulation (calculated as a fraction of control levels) of whole kidney expression of type 2 Na-P(i) cotransporter (NaPi-2; 16 +/- 6%), type 3 Na/H exchanger (NHE3; 42 +/- 7%), Na-K-ATPase (55 +/- 2%), and bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1; 25 +/- 4%). In contrast, an upregulation of the Ca(2+)-sensing receptor (CaR) was observed. Rats treated with moderate-dose PTH exhibited unchanged GFR but decreased urinary concentration. The whole kidney expression of NHE3 (52 +/- 8%) and NaPi-2 (26 +/- 5%) was persistently decreased, whereas BSC-1 and Na-K-ATPase protein levels were not altered. CaR expression was also increased. Moreover, rats treated with low-dose PTH showed very mild hypercalcemia but unchanged GFR, normal urinary concentration, and unchanged expression of Na transporters and CaR. In conclusion, the reduced expression of major renal Na transporters is likely to play a role in the increased urinary Na excretion and decreased urinary concentration in rats with PTH-induced hypercalcemia. Moreover, the increase in the CaR in the thick ascending limb (TAL) may indicate a potential role of the CaR in inhibiting Na transport in the TAL.
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PMID:Reduced expression of renal Na+ transporters in rats with PTH-induced hypercalcemia. 1462 99

We aimed to examine the effects of angiotensin II AT(1) receptor blocker on the expression of major renal sodium transporters and aquaporin-2 (AQP2) in rats with chronic renal failure (CRF). During 2 wks after 5/6 nephrectomy or sham operation, both CRF rats (n=10) and sham-operated control rats (n=7) received a fixed amount of low sodium diet and had free access to water. CRF rats (n=10) were divided into two groups which were either candesartan-treated (CRF-C, n=4) or vehicle-treated (CRF-V, n=6). Both CRF-C and CRF-V demonstrated azotemia, decreased GFR, polyuria, and decreased urine osmolality compared with sham-operated rats. When compared with CRF-V, CRF-C was associated with significantly higher BUN levels and lower remnant kidney weight. Semiquantitative immunoblotting demonstrated decreased AQP2 expression in both CRF-C (54% of control levels) and CRF-V (57%), whereas BSC-1 expression was increased in both CRF groups. Particularly, CRF-C was associated with higher BSC-1 expression (611%) compared with CRF-V (289%). In contrast, the expression of NHE3 (25%) and TSC (27%) was decreased in CRF-C, whereas no changes were observed in CRF-V. In conclusion, 1) candesartan treatment in an early phase of CRF is associated with decreased renal hypertrophy and increased BUN level; 2) decreased AQP2 level in CRF is likely to play a role in the decreased urine concentration, and the downregulation is not altered in response to candesartan treatment; 3) candesartan treatment decreases NHE3 and TSC expression; and 4) an increase of BSC-1 is prominent in candesartan-treated CRF rats, which could be associated with the increased delivery of sodium and water to the thick ascending limb.
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PMID:Angiotensin II AT1 receptor blockade changes expression of renal sodium transporters in rats with chronic renal failure. 1583 96

The effects of long-term diabetes in the presence of established nephropathy on tubular function remains poorly understood. We evaluated the levels of the main sodium and water transport proteins expressed in the kidney after long-term (8 weeks) of streptozotocin (STZ)-induced type 1 diabetes mellitus (DM) in untreated (D) and insulin (4 U/s.c./day)-treated (D+I) rats. D animals presented upregulation ( approximately 4.5-fold) of Na/glucose cotransporter (SGLT1), whereas the alpha-subunit of the epithelial sodium channel (alpha-ENaC) and aquaporin 1 (AQP1) were downregulated ( approximately 20 and 30% respectively) with no change in the Na/H exchanger (NHE3), Na/Cl cotransporter (TSC) and AQP2. Insulin replacement partially prevented these alterations and caused increases in the expression of alpha-ENaC and AQP2. These effects suggest an action of insulin in the tubular transport properties. The upregulation of SGLT1 may constitute a mechanism to prevent greater glucose losses in the urine but it may result in glucotoxicity to the proximal epithelial cells contributing to the diabetic nephropathy. The decrease of alpha-ENaC in D animals may compensate for the increased sodium reabsorption via SGLT1 resulting in discrete natriuresis. DM-induced polyuria was not due to changes in AQP2 expression.
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PMID:Effect of long-term type 1 diabetes on renal sodium and water transporters in rats. 1794 18

Vitamin D receptor (VDR)-null mice develop polyuria, but the underlying mechanism remains unknown. In this study, we investigated the relationship between vitamin D and homeostasis of water and electrolytes. VDR-null mice had polyuria, but the urine osmolarity was normal as a result of high salt excretion. The urinary responses to water restriction and to vasopressin were similar between wild-type and VDR-null mice, suggesting intact fluid-handling capacity in VDR-null mice. Compared with wild-type mice, however, renin and angiotensin II were dramatically upregulated in the kidney and brain of VDR-null mice, leading to a marked increase in water intake and salt appetite. Angiotensin II-mediated upregulation of intestinal NHE3 expression partially explained the increased salt absorption and excretion in VDR-null mice. In the brain of VDR-null mice, expression of c-Fos, which is known to associate with increased water intake, was increased in the hypothalamic paraventricular nucleus and the subfornical organ. Treatment with an angiotensin II type 1 receptor antagonist normalized water intake, urinary volume, and c-Fos expression in VDR-null mice. Furthermore, despite a salt-deficient diet to reduce intestinal salt absorption, VDR-null mice still maintained the increased water intake and urinary output. Together, these data indicate that the polyuria observed in VDR-null mice is not caused by impaired renal fluid handling or increased intestinal salt absorption but rather is the result of increased water intake induced by the increase in systemic and brain angiotensin II.
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PMID:Loss of vitamin D receptor produces polyuria by increasing thirst. 1883 38


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