Normal Urine Concentrating Ability in Magnesium Depletion

1972 ◽  
Vol 43 (6) ◽  
pp. 723-729 ◽  
Author(s):  
S. M. Suh ◽  
J. Sellors
Keyword(s):  
Water Deprivation ◽  
Urine Osmolality ◽  
Urine Concentration ◽  
Potassium Depletion ◽  
Magnesium Depletion ◽  
Normal Urine ◽  
Urine Concentrating Ability

1. We studied urine concentrating ability in ten magnesium-depleted puppies and compared the results with those of match-fed, littermate controls. 2. The experimental puppies became hypomagnesaemic and hypocalcaemic without evidence of potassium depletion. After 24 h of food and water deprivation, urine osmolality increased to 1350 ± 340 mosm/kg of water. This value did not differ from that of control animals. 3. We also studied urine concentrating ability in a child with primary hypomagnesaemia and secondary hypocalcaemia. He could achieve a urine concentration of 1080 mosm/kg of water after 20 h of water deprivation when he was hypomagnesaemic and hypocalcaemic. 4. We conclude that urine concentrating ability is normal in magnesium depletion uncomplicated by hypercalcaemia or severe potassium depletion.

scholarly journals mPGES-1 deletion potentiates urine concentrating capability after water deprivation

2012 ◽  
Vol 302 (8) ◽  
pp. F1005-F1012 ◽  
Author(s):  
Zhanjun Jia ◽  
Gang Liu ◽  
Maicy Downton ◽  
Zheng Dong ◽  
Aihua Zhang ◽  
...  
Keyword(s):  
Water Deprivation ◽  
Potential Role ◽  
Urine Volume ◽  
Renal Medulla ◽  
Urine Osmolality ◽  
Protein Abundance ◽  
Wild Type ◽  
Control Groups ◽  
Urine Concentrating Ability

PGE2 plays an important role in the regulation of fluid metabolism chiefly via antagonizing vasopressin-induced osmotic permeability in the distal nephron, but its enzymatic sources remain uncertain. The present study was undertaken to investigate the potential role of microsomal PGE synthase (mPGES)-1 in the regulation of urine concentrating ability after water deprivation (WD). Following 24-h WD, wild-type (WT) mice exhibited a significant reduction in urine volume, accompanied by a significant elevation in urine osmolality compared with control groups. In contrast, in response to WD, mPGES-1 knockout (KO) mice had much less urine volume and higher urine osmolality. Analysis of plasma volume by measurement of hematocrit and by using a nanoparticle-based method consistently demonstrated that dehydrated WT mice were volume depleted, which was significantly improved in the KO mice. WD induced a twofold increase in urinary PGE2 output in WT mice, which was completely blocked by mPGES-1 deletion. At baseline, the KO mice had a 20% increase in V2 receptor mRNA expression in the renal medulla but not the cortex compared with WT controls; the expression was unaffected by WD irrespective of the genotype. In response to WD, renal medullary aquaporin-2 (AQP2) mRNA exhibited a 60% increase in WT mice, and this increase was greater in the KO mice. Immunoblotting demonstrated increased renal medullary AQP2 protein abundance in both genotypes following WD, with a greater increase in the KO mice. Similar results were obtained by using immunohistochemistry. Paradoxically, plasma AVP response to WD seen in WT mice was absent in the KO mice. Taken together, these results suggest that mPGES-1-derived PGE2 reduces urine concentrating ability through suppression of renal medullary expression of V2 receptors and AQP2 but may enhance it by mediating the central AVP response.

COX-2 disruption leads to increased central vasopressin stores and impaired urine concentrating ability in mice

2011 ◽  
Vol 301 (6) ◽  
pp. F1303-F1313 ◽  
Author(s):  
Rikke Nørregaard ◽  
Kirsten Madsen ◽  
Pernille B. L. Hansen ◽  
Peter Bie ◽  
Sugarna Thavalingam ◽  
...  
Keyword(s):  
Water Deprivation ◽  
Collecting Duct ◽  
Mrna Level ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Glomerular Injury ◽  
Plasma Urea ◽  
Cox 2 ◽  
Response To Water ◽  
Urine Concentrating Ability

It was hypothesized that cyclooxygenase-2 (COX-2) activity promotes urine concentrating ability through stimulation of vasopressin (AVP) release after water deprivation (WD). COX-2-deficient (COX-2−/−, C57BL/6) and wild-type (WT) mice were water deprived for 24 h, and water balance, central AVP mRNA and peptide level, AVP plasma concentration, and AVP-regulated renal transport protein abundances were measured. In male COX-2−/−, basal urine output and water intake were elevated while urine osmolality was decreased compared with WT. Water deprivation resulted in lower urine osmolality, higher plasma osmolality in COX-2−/− mice irrespective of gender. Hypothalamic AVP mRNA level increased and was unchanged between COX-2−/− and WT after WD. AVP peptide content was higher in COX-2−/− compared with WT. At baseline, plasma AVP concentration was elevated in conscious chronically catheterized COX-2−/− mice, but after WD plasma AVP was unchanged between COX-2−/− and WT mice (43 ± 11 vs. 70 ± 16 pg/ml). Renal V2 receptor abundance was downregulated in COX-2−/− mice. Medullary interstitial osmolality increased and did not differ between COX-2−/− and WT after WD. Aquaporin-2 (AQP2; cortex-outer medulla), AQP3 (all regions), and UT-A1 (inner medulla) protein abundances were elevated in COX-2−/− at baseline and further increased after WD. COX-2−/− mice had elevated plasma urea and creatinine and accumulation of small subcapsular glomeruli. In conclusion, hypothalamic COX-2 activity is not necessary for enhanced AVP expression and secretion in response to water deprivation. Renal medullary COX-2 activity negatively regulates AQP2 and -3. The urine concentrating defect in COX-2−/− is likely caused by developmental glomerular injury and not dysregulation of AVP or collecting duct aquaporins.

scholarly journals Aquaporins in Renal Diseases

2019 ◽  
Vol 20 (2) ◽  
pp. 366 ◽  
Author(s):  
Jinzhao He ◽  
Baoxue Yang
Keyword(s):  
Kidney Diseases ◽  
Kidney Injury ◽  
Concentration Function ◽  
Urine Concentration ◽  
Renal Diseases ◽  
Chronic Kidney Diseases ◽  
Transmembrane Channels ◽  
Normal Urine ◽  
And Function ◽  
Urine Concentrating Ability

Aquaporins (AQPs) are a family of highly selective transmembrane channels that mainly transport water across the cell and some facilitate low-molecular-weight solutes. Eight AQPs, including AQP1, AQP2, AQP3, AQP4, AQP5, AQP6, AQP7, and AQP11, are expressed in different segments and various cells in the kidney to maintain normal urine concentration function. AQP2 is critical in regulating urine concentrating ability. The expression and function of AQP2 are regulated by a series of transcriptional factors and post-transcriptional phosphorylation, ubiquitination, and glycosylation. Mutation or functional deficiency of AQP2 leads to severe nephrogenic diabetes insipidus. Studies with animal models show AQPs are related to acute kidney injury and various chronic kidney diseases, such as diabetic nephropathy, polycystic kidney disease, and renal cell carcinoma. Experimental data suggest ideal prospects for AQPs as biomarkers and therapeutic targets in clinic. This review article mainly focuses on recent advances in studying AQPs in renal diseases.

Urine concentrating defect in prostaglandin EP1-deficient mice

2007 ◽  
Vol 292 (2) ◽  
pp. F868-F875 ◽  
Author(s):  
Chris R. J. Kennedy ◽  
Huaqi Xiong ◽  
Sherine Rahal ◽  
Jacqueline Vanderluit ◽  
Ruth S. Slack ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Water Channel ◽  
Significant Proportion ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Urine Concentration ◽  
Prostaglandin E ◽  
Rt Pcr ◽  
Urine Concentrating Ability

We investigated the role of the prostaglandin E2 (PGE2) EP1 receptor in modulating urine concentration as it is expressed along the renal collecting duct where arginine-vasopressin (AVP) exerts its anti-diuretic activity, and in the paraventricular and supraoptic nuclei of the hypothalamus where AVP is synthesized. The urine osmolality of EP1-null mice (EP1−/−) failed to match levels achieved by wild-type (WT) counterparts upon water deprivation (WD) for 24 h. This difference was reflected by higher plasma osmolality in WD EP1−/− mice. Along the collecting duct, the induction and subapical to plasma membrane translocation of the aquaporin-2 water channel in WD EP1−/− mice appeared equivalent to that of WD WT mice as determined by quantitative RT-PCR and immunohistochemistry. However, medullary interstitial osmolalities dropped significantly in EP1−/− mice following WD. Furthermore, urinary AVP levels of WD EP1−/− mice were significantly lower than those of WD WT mice. This deficit could be traced back to a blunted induction of hypothalamic AVP mRNA expression in WD EP1−/− mice as determined by quantitative RT-PCR. Administration of the AVP mimetic [deamino-Cys1,d-Arg8]-vasopressin restored a significant proportion of the urine concentrating ability of WD EP1−/− mice. When mice were water loaded to suppress endogenous AVP production, urine osmolalities increased equally for WT and EP1−/− mice. These data suggest that PGE2 modulates urine concentration by acting at EP1 receptors, not in the collecting duct, but within the hypothalamus to promote AVP synthesis in response to acute WD.

Impairment of renal medullary osmolyte accumulation in potassium-depleted rats

1994 ◽  
Vol 267 (1) ◽  
pp. F139-F145 ◽  
Author(s):  
T. Nakanishi ◽  
Y. Takamitsu ◽  
H. Nakahama ◽  
M. Sugita
Keyword(s):  
Water Deprivation ◽  
Renal Medulla ◽  
Urine Osmolality ◽  
Untreated Group ◽  
Urinary Concentration ◽  
Potassium Depletion ◽  
Water Diuresis ◽  
Osmolyte Accumulation ◽  
Group Water ◽  
The Relationship

To determine the relationship between accumulation of osmolytes and maximal urinary concentration in potassium depletion, we tested the effects of experimental water diuresis or potassium depletion on osmolytes in the renal medulla of rats. Hyperosmotic stress was imposed by 4 days of water deprivation for the purpose of establishing the maximal concentrating ability or by the infusion of sodium for the purpose of loading the equal amounts of sodium to the renal medulla. In the diuresis group, water deprivation failed to increase betaine, sorbitol, and taurine contents to the same level as the untreated group, although sodium infusion increased betaine and sorbitol. In the potassium depletion group followed by water deprivation, urine osmolality (2,490 +/- 241 vs. 3,425 +/- 268 mosmol/kgH2O) and all osmolytes were significantly lower than in the untreated group. In response to hyperosmolality with sodium infusion, myo-inositol and glycerophosphorylcholine contents rose to the level of the untreated group. Medullary betaine (67.6 +/- 6.8 vs. 99.5 +/- 8.9), taurine (44.7 +/- 2.4 vs. 61.4 +/- 6.2) and sorbitol (35.6 +/- 4.4 vs. 57.0 +/- 8.4 mmol/kg protein) contents were reduced in potassium-depleted rats when the renal medulla was as hypertonic as in the untreated group. In conclusion, the processing of betaine, taurine, and sorbitol accumulation appeared to be impaired in potassium depletion.

Mice with targeted disruption of the acyl-CoA binding protein display attenuated urine concentrating ability and diminished renal aquaporin-3 abundance

2012 ◽  
Vol 302 (8) ◽  
pp. F1034-F1044 ◽  
Author(s):  
Stine Langaa ◽  
Maria Bloksgaard ◽  
Signe Bek ◽  
Ditte Neess ◽  
Rikke Nørregaard ◽  
...  
Keyword(s):  
Water Deprivation ◽  
Binding Protein ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Plasma Concentrations ◽  
Relative Weight ◽  
Urine Osmolality ◽  
Cell Types ◽  
Targeted Disruption ◽  
Urine Concentrating Ability

The acyl-CoA binding protein (ACBP) is a small intracellular protein that specifically binds and transports medium to long-chain acyl-CoA esters. Previous studies have shown that ACBP is ubiquitously expressed but found at particularly high levels in lipogenic cell types as well as in many epithelial cells. Here we show that ACBP is widely expressed in human and mouse kidney epithelium, with the highest expression in the proximal convoluted tubules. To elucidate the role of ACBP in the renal epithelium, mice with targeted disruption of the ACBP gene (ACBP−/−) were used to study water and NaCl balance as well as urine concentrating ability in metabolic cages. Food intake and urinary excretion of Na+ and K+ did not differ between ACBP−/− and +/+ mice. Interestingly, however, water intake and diuresis were significantly higher at baseline in ACBP−/− mice compared with that of +/+ mice. Subsequent to 20-h water deprivation, ACBP−/− mice exhibited increased diuresis, reduced urine osmolality, elevated hematocrit, and higher relative weight loss compared with +/+ mice. There were no significant differences in plasma concentrations of renin, corticosterone, and aldosterone between mice of the two genotypes. After water deprivation, renal medullary interstitial fluid osmolality and concentrations of Na+, K+, and urea did not differ between genotypes and cAMP excretion was similar. Renal aquaporin-1 (AQP1), -2, and -4 protein abundances did not differ between water-deprived +/+ and ACBP−/− mice; however, ACBP−/− mice displayed increased apical targeting of pS256-AQP2. AQP3 abundance was lower in ACBP−/− mice than in +/+ control animals. Thus we conclude that ACBP is necessary for intact urine concentrating ability. Our data suggest that the deficiency in urine concentrating ability in the ACBP−/− may be caused by reduced AQP3, leading to impaired efflux over the basolateral membrane of the collecting duct.

scholarly journals AT1a receptor signaling is required for basal and water deprivation-induced urine concentration in AT1a receptor-deficient mice

2012 ◽  
Vol 303 (5) ◽  
pp. F746-F756 ◽  
Author(s):  
Xiao C. Li ◽  
Yuan Shao ◽  
Jia L. Zhuo
Keyword(s):  
Adenylyl Cyclase ◽  
Water Deprivation ◽  
Urine Osmolality ◽  
Urine Concentration ◽  
Ang Ii ◽  
Receptor Signaling ◽  
Urine Excretion ◽  
Lower Systolic Blood Pressure ◽  
At1a Receptor ◽  
Total Lysate

It is well recognized that ANG II interacts with arginine vasopressin (AVP) to regulate water reabsorption and urine concentration in the kidney. The present study used ANG II type 1a (AT1a) receptor-deficient (Agtr1a−/−) mice to test the hypothesis that AT1a receptor signaling is required for basal and water deprivation-induced urine concentration in the renal medulla. Eight groups of wild-type (WT) and Agtr1a−/− mice were treated with or without 24-h water deprivation and 1-desamino-8-d-AVP (DDAVP; 100 ng/h ip) for 2 wk or with losartan (10 mg/kg ip) during water deprivation. Under basal conditions, Agtr1a−/− mice had lower systolic blood pressure ( P < 0.01), greater than threefold higher 24-h urine excretion (WT mice: 1.3 ± 0.1 ml vs. Agtr1a−/− mice: 5.9 ± 0.7 ml, P < 0.01), and markedly decreased urine osmolality (WT mice: 1,834 ± 86 mosM/kg vs. Agtr1a−/− mice: 843 ± 170 mosM/kg, P < 0.01), without significant changes in 24-h urinary Na+ excretion. These responses in Agtr1a−/− mice were associated with lower basal plasma AVP (WT mice: 105 ± 8 pg/ml vs. Agtr1a−/− mice: 67 ± 6 pg/ml, P < 0.01) and decreases in total lysate and membrane aquaporin-2 (AQP2; 48.6 ± 7% of WT mice, P < 0.001) and adenylyl cyclase isoform III (55.6 ± 8% of WT mice, P < 0.01) proteins. Although 24-h water deprivation increased plasma AVP to the same levels in both strains, 24-h urine excretion was still higher, whereas urine osmolality remained lower, in Agtr1a−/− mice ( P < 0.01). Water deprivation increased total lysate AQP2 proteins in the inner medulla but had no effect on adenylyl cyclase III, phosphorylated MAPK ERK1/2, and membrane AQP2 proteins in Agtr1a−/− mice. Furthermore, infusion of DDAVP for 2 wk was unable to correct the urine-concentrating defects in Agtr1a−/− mice. These results demonstrate that AT1a receptor-mediated ANG II signaling is required to maintain tonic AVP release and regulate V2 receptor-mediated responses to water deprivation in the inner medulla.

Urine-concentrating defects exacerbate with age in male offspring with a low-nephron endowment

2011 ◽  
Vol 301 (6) ◽  
pp. F1168-F1176 ◽  
Author(s):  
Reetu R. Singh ◽  
Kate M. Denton ◽  
John F. Bertram ◽  
John Dowling ◽  
Karen M. Moritz
Keyword(s):  
Water Deprivation ◽  
Sham Group ◽  
Chronic Renal Disease ◽  
Urine Osmolality ◽  
Treatment Groups ◽  
Nephron Endowment ◽  
Renal Expression ◽  
Male Sheep ◽  
Urine Concentrating Ability ◽  
Concentrating Defect

Fetal uninephrectomy (uni-x) in male sheep at 100 days of gestation (term = 150 days) reduces overall nephron endowment without affecting birth weight. Offspring have a lower glomerular filtration rate (GFR) and elevated mean arterial pressure (MAP) at 6 mo of age. This study investigated whether this reduction in renal function was associated with impaired urine-concentrating ability at 6 mo of age and exacerbated with ageing (4 yr) and examined response to 1) nonpressor dose of exogenous arginine vasopressin (AVP; 0.2 μg·kg−1·h−1 iv) and 2) 30 h of water deprivation. Basal MAP was higher in uni-x animals at both ages, and became further elevated with age compared with the sham group (elevation in MAP with age; sham: ∼4 mmHg, uni-x: 9 mmHg, Pgroup × age < 0.01). GFR declined with ageing in both groups with the decrease being greater with age in the uni-x group (further 26%, Pgroup × age < 0.001). In response to AVP infusion, urine osmolality increased in both treatment groups; this response was significantly lower in the uni-x animals and became further reduced with ageing. Uni-x animals had reduced renal expression of vasopressin-2 receptor and aquaporin-2 at both ages ( P < 0.01). The increase in plasma AVP levels in response to dehydration was similar between the treatment groups, suggesting the urine-concentrating defect was associated with these renal gene changes rather than defects in AVP secretion. Renal insufficiency due to a low-nephron endowment increases the risk of hypertension and chronic renal disease and may incur greater vulnerability to physiological challenges such as water deprivation as observed in the uni-x animals.

THE USE OF CHLORPROPAMIDE IN DIABETES INSIPIDUS IN CHILDREN

PEDIATRICS ◽  
1970 ◽  
Vol 45 (2) ◽  
pp. 236-245
Author(s):  
Robert M. Ehrlich ◽  
Sang Whay Kooh
Keyword(s):  
Diabetes Insipidus ◽  
Water Deprivation ◽  
Plasma Insulin ◽  
Urine Volume ◽  
Insulin Response ◽  
Urine Osmolality ◽  
Post Traumatic ◽  
Term Management ◽  
Plasma Insulin Response

Oral chlorpropamide was administered to 17 children with diabetes insipidus (D.I.). The cause of the D.I. was idiopathic, six; histiocytosis, five; craniopharyngioma, three; pinealoma, two, and post-traumatic, one. Twenty-four-hour urine volume and measurements of serum and urine osmolality at the beginning and end of a 7-hour water deprivation test were used to evaluatechlorpropamide therapy. Administration of 150 to 400 mg of chlorpropamide per day by mouth caused a reduction in urine volume in all patients (range 8 to 67%). No change in aldosterone, 17-hydroxycorticoids, or electrolyte excretion was noted. Serum electrolytes and glomerular filtration rate were not affected by therapy. Glucose tolerance and plasma insulin response remained normal in those patients tested. Mild leucine sensitivity without significant change in plasma insulin was induced in four children. During water deprivation, seven patients with secondary D.I. but only one with idiopathic D.I. produced hypertonic urine. Hypoglycemia developed in seven children and is the major hazard of treatment. Long-term management of D.I. has been possible in nine children. Oral chlorpropamide is a useful drug in children with vasopressin-sensitive diabetes insipidus.

Meclofenamate and urine concentration with and without exposure of the renal papilla

1981 ◽  
Vol 240 (5) ◽  
pp. F423-F429 ◽  
Author(s):  
R. J. Roman ◽  
C. Lechene
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Urine Osmolality ◽  
Urine Concentration ◽  
Prostaglandin Synthesis ◽  
Urine Flow ◽  
Renal Papilla ◽  
Arterial Blood ◽  
Pelvic Urine

The recent finding that inhibitors of prostaglandin synthesis prevent the fall in urine concentration produced by papillary exposure challenges the hypothesis that contact between the pelvic urine and papilla is essential to the renal concentrating process. The present study examines the change in urine osmolality produced by exposure of the renal papilla in rats given meclofenamate. In control animals urine osmolality(Uosmol) decreased 57% after 2 h of exposure of the renal papilla. In rats given meclofenamate 4 mg/kg urine osmolality increased 16%, urine flow decreased 30%, and glomerular filtration rate was unchanged in the nonexposed kidney. Meclofenamate, however, did not alter the decrease in Uosmol seen in the kidney with the exposed papilla. Meclofenamate 10 mg/kg was also ineffective in preventing the fall in urine osmolality produced by papillary exposure, although this higher dose decreased glomerular filtration rate and arterial blood pressure. These results are consistent with the finding that pelvic urine urea is important to the urinary concentrating process and with the hypothesis that urine osmolality falls after papillary exposure because contact between pelvic urine and papilla is interrupted.

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