NaCl and/or urea infusion fails to increase renal inner medullary myo-inositol in protein-deprived rats

1996 ◽  
Vol 271 (6) ◽  
pp. F1255-F1263
Author(s):  
T. Nakanishi ◽  
F. Nishihara ◽  
A. Yamauchi ◽  
S. Yamamoto ◽  
M. Sugita ◽  
...  
Keyword(s):  
Water Deprivation ◽  
Urine Concentration ◽  
Organic Osmolytes ◽  
Protein Deprivation ◽  
Organic Osmolyte ◽  
Sodium Dependent ◽  
Protein Feeding ◽  
The Relationship ◽  
Urea Infusion ◽  
Tissue Sodium

As we recently demonstrated that in potassium depletion a decrease in inner medullary organic osmolytes might precede and cause a renal concentrating defect, we hypothesized that in the protein deprivation the same mechanism may occur. To clarify the relationship between renal medullary organic osmolytes and urine concentration defects during protein deprivation, we examined the effect of protein malnutrition on organic osmolyte content after water deprivation or sodium and/or urea infusion. Water deprivation did not restore urine urea and osmolality or tissue sodium and urea in protein-deprived rats to control levels. NaCl infusion only increased urinary and medullary Na. Urea infusion increased medullary urea but not urine urea. NaCl plus urea infusion increased only urinary sodium and urea. Regardless of the protocols of hyperosmolality used, protein deprivation significantly decreased the medullary contents of myo-inositol and taurine and the level of sodium-dependent myo-inositol transporter mRNA. We conclude that factors other than NaCl and urea but associated with protein feeding are responsible for the decreased accumulation of organic osmolytes.

The volume-sensitive organic osmolyte-anion channel VSOAC is regulated by nonhydrolytic ATP binding

1994 ◽  
Vol 267 (5) ◽  
pp. C1203-C1209 ◽  
Author(s):  
P. S. Jackson ◽  
R. Morrison ◽  
K. Strange
Keyword(s):  
Ketone Bodies ◽  
Anion Channel ◽  
Metabolic Inhibitors ◽  
Cell Swelling ◽  
Organic Osmolytes ◽  
Pipette Solution ◽  
Organic Osmolyte ◽  
Atp Levels ◽  
Patch Pipette ◽  
Taurine Efflux

Efflux of intracellular organic osmolytes to the external medium is a ubiquitous response to cell swelling. Accumulating evidence indicates that volume regulatory loss of structurally unrelated organic osmolytes from cells is mediated by a relatively nonselective volume-sensitive anion channel. In C6 cells, we have termed this channel VSOAC for volume-sensitive organic osmolyte-anion channel. Swelling-induced activation of VSOAC required the presence of ATP or nonhydrolyzable ATP analogues [adenosine 5'-O-(3-thiotriphosphate), adenylylmethyl-enediphosphonate (AMP-PCP), or 5'-adenylylimidodiphosphate] in the patch pipette. Sustained activation of VSOAC also required ATP. Channel rundown was observed when cellular ATP levels were lowered by intracellular dialysis with the patch pipette solution. Rundown was prevented by the ATP analogue AMP-PCP. Passive swelling-induced myo-[3H]inositol and [3H]taurine efflux was blocked by metabolic inhibitors that decreased cellular ATP levels. Titration of cellular ATP levels with azide demonstrated that the apparent dissociation constant (Kd) for ATP of both myo-inositol and taurine efflux was approximately 1.7 mM. The high Kd for ATP indicates that cellular metabolic state plays an important role in modulating organic osmolyte loss. Regulation of VSOAC activity by ATP prevents depletion of metabolically expensive organic osmolytes when cellular energy production is reduced. In addition, ATP-dependent regulation provides essential feedback to minimize the loss of energy-producing carbon sources such as pyruvate, short-chain fatty acids, ketone bodies, and amino acids, which readily permeate this channel.

scholarly journals Validation of Surrogates of Urine Osmolality in Population Studies

2017 ◽  
Vol 46 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Sonia Youhanna ◽  
Lise Bankir ◽  
Paul Jungers ◽  
David Porteous ◽  
Ozren Polasek ◽  
...  
Keyword(s):  
Metabolic Diseases ◽  
Large Population ◽  
Urine Osmolality ◽  
Population Based ◽  
Epidemiologic Studies ◽  
Urine Concentration ◽  
Total N ◽  
Mean Differences ◽  
Relationship Of ◽  
The Relationship

Background: The importance of vasopressin and/or urine concentration in various kidney, cardiovascular, and metabolic diseases has been emphasized recently. Due to technical constraints, urine osmolality (Uosm), a direct reflect of urinary concentrating activity, is rarely measured in epidemiologic studies. Methods: We analyzed 2 possible surrogates of Uosm in 4 large population-based cohorts (total n = 4,247) and in patients with chronic kidney disease (CKD, n = 146). An estimated Uosm (eUosm) based on the concentrations of sodium, potassium, and urea, and a urine concentrating index (UCI) based on the ratio of creatinine concentrations in urine and plasma were compared to the measured Uosm (mUosm). Results: eUosm is an excellent surrogate of mUosm, with a highly significant linear relationship and values within 5% of mUosm (r = 0.99 or 0.98 in each population cohort). Bland-Altman plots show a good agreement between eUosm and mUosm with mean differences between the 2 variables within ±24 mmol/L. This was verified in men and women, in day and night urine samples, and in CKD patients. The relationship of UCI with mUosm is also significant but is not linear and exhibits more dispersed values. Moreover, the latter index is no longer representative of mUosm in patients with CKD as it declines much more quickly with declining glomerular filtration rate than mUosm. Conclusion: The eUosm is a valid marker of urine concentration in population-based and CKD cohorts. The UCI can provide an estimate of urine concentration when no other measurement is available, but should be used only in subjects with normal renal function.

scholarly journals Race, sex, and the regulation of urine osmolality: observations made during water deprivation

2010 ◽  
Vol 299 (3) ◽  
pp. R977-R980 ◽  
Author(s):  
Michael L. Hancock ◽  
Daniel G. Bichet ◽  
George J. Eckert ◽  
Lise Bankir ◽  
Mary Anne Wagner ◽  
...  
Keyword(s):  
Water Conservation ◽  
Water Deprivation ◽  
Collecting Duct ◽  
Urine Osmolality ◽  
Thick Ascending Limb ◽  
Race Difference ◽  
Water Reabsorption ◽  
Blacks And Whites ◽  
Relationship Of ◽  
The Relationship

A more concentrated urine is excreted by blacks than whites and by men than women. The purpose of this study was to explore the physiological bases for the race and sex effects during water deprivation when osmoregulation is challenged and differences are amplified. Drinking water was withheld from 17 blacks (10 men) and 19 whites (9 men) for 24 h. Vasopressin (VP) levels and osmolality in plasma (Posmol) and urine (Uosmol) were measured basally and then every 4 h. Uosmol was higher in blacks at baseline ( P = 0.01) and during water deprivation ( P = 0.046). Before and during water deprivation, no differences were seen in levels of VP, Posmol, or the VP-Uosmol relationship between blacks and whites. Although VP levels were initially higher in men ( P < 0.02 for samples collected over the first 12 h), over the last 12 h of water deprivation, Uosmol was higher ( P = 0.027) and more responsive to the level of VP (in terms of slopes, P = 0.0001) in women than men. Our results suggest that, after a period of water deprivation, there develops a sensitivity of the collecting duct to VP that is greater in women. Although Uosmol is higher in blacks, the race difference in water conservation did not appear to result from differences in the level of VP or the sensitivity of the collecting duct to VP. Upstream effects such as Na+ uptake in the thick ascending limb, with its ensuing effects on water reabsorption, need to be considered in future studies of the relationship of race to water conservation.

scholarly journals Antidiuretic Hormone and Serum Osmolarity Physiology and Related Outcomes: What Is Old, What Is New, and What Is Unknown?

2019 ◽  
Vol 104 (11) ◽  
pp. 5406-5420 ◽  
Author(s):  
Mehmet Kanbay ◽  
Sezen Yilmaz ◽  
Neris Dincer ◽  
Alberto Ortiz ◽  
Alan A Sag ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Antidiuretic Hormone ◽  
English Language ◽  
Fluid Intake ◽  
Evidence Synthesis ◽  
Taste Receptor ◽  
Urine Concentration ◽  
Disease States ◽  
The Relationship ◽  
Therapeutic Perspective

Abstract Context Although the physiology of sodium, water, and arginine vasopressin (AVP), also known as antidiuretic hormone, has long been known, accumulating data suggest that this system operates as a more complex network than previously thought. Evidence Acquisition English-language basic science and clinical studies of AVP and osmolarity on the development of kidney and cardiovascular disease and overall outcomes. Evidence Synthesis Apart from osmoreceptors and hypovolemia, AVP secretion is modified by novel factors such as tongue acid-sensing taste receptor cells and brain median preoptic nucleus neurons. Moreover, pharyngeal, esophageal, and/or gastric sensors and gut microbiota modulate AVP secretion. Evidence is accumulating that increased osmolarity, AVP, copeptin, and dehydration are all associated with worse outcomes in chronic disease states such as chronic kidney disease (CKD), diabetes, and heart failure. On the basis of these pathophysiological relationships, an AVP receptor 2 blocker is now licensed for CKD related to polycystic kidney disease. Conclusion From a therapeutic perspective, fluid intake may be associated with increased AVP secretion if it is driven by loss of urine concentration capacity or with suppressed AVP if it is driven by voluntary fluid intake. In the current review, we summarize the literature on the relationship between elevated osmolarity, AVP, copeptin, and dehydration with renal and cardiovascular outcomes and underlying classical and novel pathophysiologic pathways. We also review recent unexpected and contrasting findings regarding AVP physiology in an attempt to explain and understand some of these relationships.

Body composition in vivo. IV. Comparisons of the antipyrine and N-acetyl-4-aminoantipyrine spaces in goats

1964 ◽  
Vol 15 (1) ◽  
pp. 180 ◽  
Author(s):  
BA Panaretto ◽  
JT Reid
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Water Deprivation ◽  
Rumen Fluid ◽  
Body Water ◽  
Satisfactory Explanation ◽  
Good Relationship ◽  
The Relationship ◽  
Volumes Of Distribution

The effects of feed and water deprivation on the antipyrine (AP) spaces were studied in five goats. Generally there was no good relationship between loss in body weight, following 24 or 48 hr of feed and water deprivation, and changes in the AP space. The AP spaces were variable and the rates at which AP disappeared from the circulations of our animals also varied. No satisfactory explanation could be given. Estimates of body water made with N-acetyl-4-aminoantipyrine (NAAP) were always smaller than the simultaneous AP spaces in any animal. Two experiments were made to study these differences in the volumes of distribution of AP and NAAP when both chemicals were injected simultaneously. Both chemicals yielded anomalous spaces in the first experiment when the ruminal contents had been augmented with water, while better results were obtained when the ruminal contents had been augmented with rumen fluid in the second experiment. Intravenously administered AP appeared in the rumen contents of the goats at greater concentration than NAAP which had been given at the same time, and the differences between the two spaces appeared to be due to this. The rates at which both substances disappeared from the circulation of these animals are given, and the relationship between their disappearance from the blood and appearance in the rumen is discussed.

The Compability with Enzyme Activity of Unusual Organic Osmolytes from Mangrove Red Algae

1996 ◽  
Vol 23 (5) ◽  
pp. 577 ◽  
Author(s):  
U Karsten ◽  
KD Barrow ◽  
O Nixdorf ◽  
RJ King
Keyword(s):  
Red Algae ◽  
Citric Acid Cycle ◽  
Compatible Solutes ◽  
Pentose Phosphate ◽  
Organic Osmolytes ◽  
Maximum Solubility ◽  
Organic Osmolyte ◽  
Negative Effect ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of organic osmolytes synthesised and accumulated by red algae from mangrove habitats were investigated on the in vitro activities of two major enzymes, one of the citric acid cycle (malate dehydrogenase, MDH) and one of the oxidative pentose phosphate pathway (glucose-6- phosphate dehydrogenase, G6PDH). These enzymes were extracted from the mangrove algae Bostrychia tenella, Caloglossa leprieurii, Catenella nipae and Stictosiphonia hookeri. In each case, activity of the enzymes was inhibited with increasing NaCl concentrations up to 600 mM . In contrast, equimolar concentrations of mannitol (the major osmolyte in C. leprieurii), sorbitol (the major osmolyte in B. Tenella and S. hookeri) and a heteroside mixture (of which floridoside is the major osmolyte in C. nipae) did not inhibit enzyme function. Dulcitol, the second most important organic osmolyte in B. tenella, exerted no negative effect at its maximum solubility of 180 rnM on the salt-sensitive MDH. These data are all consistent with the proposed function of these organic compounds as compatible solutes.

Salt effects on proline and glycine betaine levels and photosynthetic performance in Melilotus siculus, Tecticornia pergranulata and Thinopyrum ponticum measured in simulated saline conditions

2016 ◽  
Vol 43 (3) ◽  
pp. 254 ◽  
Author(s):  
Mohammad S. I. Bhuiyan ◽  
Greggory Maynard ◽  
Anantanarayanan Raman ◽  
Dennis Hodgkins ◽  
David Mitchell ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Salinity Stress ◽  
Glycine Betaine ◽  
Photosynthetic Performance ◽  
Photochemical Quenching ◽  
Organic Osmolytes ◽  
Thinopyrum Ponticum ◽  
Organic Osmolyte ◽  
Osmotic Balance ◽  
Salinity Stress Tolerance

We measured proline and glycine betaine levels and photosynthetic performance (net-photosynthetic rate (Pn), stomatal conductance (gs), maximum quantum yield of PSII (Fv/Fm) and non-photochemical quenching (NPQ)) in relation to Na+ and Cl– accumulation in Melilotus siculus (Turra) B.D.Jacks. (Fabaceae), Tecticornia pergranulata (J.M.Black) K.A.Sheph. & Paul G.Wilson (Amaranthaceae: Salicornioideae) and Thinopyrum ponticum (Podp.) Z.-W.Liu & R.-C.Wang (Poaceae) grown under saline conditions in the greenhouse. These plants were selected in this study because of their known salt-tolerance capacity and value as forage plants. Moreover, the pasture legume M. siculus is considered to have particular potential for saline land remediation because of its salinity and waterlogging tolerance. Maximum Na+ and Cl– accumulation occurred in Te. pergranulata shoots. Minimum was in Th. ponticum shoots. Maximum Na+ accumulation occurred in the roots of Te. pergranulata, whereas that of Cl– occurred in the roots of Th. ponticum. Accumulation of both Na+ and Cl– was the least in M. siculus roots. Te. pergranulata metabolized high levels of glycine betaine (110 µmol g–1 DW). M. siculus metabolized high levels of proline (6 µmol g–1 DW). Th. ponticum accumulated intermediate levels of these organic osmolytes. No significant change occurred in Fv/Fm values. Pn value increased and NPQ value decreased in Te. pergranulata with increasing salinity and the reverse occurred in both M. siculus and Th. ponticum. A negative significant correlation occurred between Pn and glycine betaine in M. siculus and Th. ponticum. A positive significant correlation occurred between NPQ and glycine betaine in M. siculus. No correlation occurred between proline and Pn, proline and NPQ in the tested three plants. Te. pergranulata could maintain cell-osmotic balance by synthesising high levels of organic osmolytes especially glycine betaine and concurrently showing the most efficient photosynthetic performance. Compared with the levels of osmolytes in Te. pergranulata, the levels of osmolytes that occur in M. siculus and Th. ponticum were insufficient to maintain cell-osmotic balance and also that M. siculus and Th. ponticum showed a lower level of photosynthetic performance. We conclude that glycine betaine is potentially the vital organic osmolyte for Te. pergranulata and Th. ponticum enabling salinity stress tolerance. However, in M. siculus, proline appears to be the potential organic osmolyte in salinity stress tolerance. In terms of the potential of these species for stabilising saline soils in central-western New South Wales, Te. pergranulata would be the candidate of choice; however, for greater pasture value Th. ponticum would be the next.

Characterization of organic osmolytes in avian renal medulla: a nonurea osmotic gradient system

1993 ◽  
Vol 264 (6) ◽  
pp. R1045-R1049
Author(s):  
Y. H. Lien ◽  
M. M. Pacelli ◽  
E. J. Braun
Keyword(s):  
Water Deprivation ◽  
Renal Cortex ◽  
Renal Medulla ◽  
Urine Osmolality ◽  
Gradient System ◽  
Osmotic Gradient ◽  
Organic Osmolytes ◽  
Before And After ◽  
Avian Kidney

We measured the organic osmolytes present in the renal cortex and medullary cones of adult female domestic fowl before and after 48 h of water deprivation. Urine osmolality increased from 198 +/- 82 to 569 +/- 42 mosmol/kgH2O after water deprivation. In water-deprived birds, the major organic osmolytes, myoinositol, betaine, and taurine, in the medullary cones increased by 40, 100, and 24%, respectively, compared with control birds. No sorbitol was detected, and glycerophosphorylcholine (GPC) content was not affected by water deprivation. In the renal cortex, only betaine content increased significantly (4.8 +/- 0.6 vs. 3.1 +/- 0.3 mmol/kg wet wt) after water deprivation. In this study, we demonstrated that birds, like mammals, accumulate organic osmolytes in response to the increased interstitial osmolality that occurs during antidiuresis. Because urea is nearly absent in the avian medullary interstitium, our observation that GPC is not osmoregulated in the avian kidney supports the idea that GPC is the “counteracting osmolyte” for urea in the mammalian kidney. Furthermore, the organic osmolytes present in avian medullary cones are remarkably similar to those of the mammalian outer medulla. This similarity may be relevant to the morphological analogy of the two regions.

Increased PGE2 excretion by dDAVP in humans depends on state of hydration

1986 ◽  
Vol 250 (6) ◽  
pp. F1008-F1012 ◽  
Author(s):  
U. Schwertschlag ◽  
J. G. Gerber ◽  
J. S. Barnes ◽  
A. S. Nies
Keyword(s):  
Water Deprivation ◽  
Urine Volume ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Water Diuresis ◽  
Water Load ◽  
Water Ingestion ◽  
Transient Rise ◽  
Relationship Of ◽  
The Relationship

The relationship of renal prostaglandin E2 (PGE2) excretion (UPGEV) to water deprivation, water diuresis, and subsequent antidiuresis by 1-desamino-8-D-arginine vasopressin (dDAVP) was studied in female volunteers. After 16 h of water deprivation, the subjects began a sustained water diuresis for 8 h. This diuresis caused a transient twofold rise in UPGEV at 2 h (P less than 0.05), which then fell back to or below baseline levels. dDAVP given during the water diuresis caused a transient rise of UPGEV as urine volume decreased and plasma osmolality fell from 277 +/- 1.5 to 271 +/- 2 mosmol/kg (P less than 0.01). Another group of subjects had the water diuresis discontinued after 4 h with dDAVP given at the 5th h when urine volume was decreasing and urine osmolality was increasing. In this setting dDAVP did not produce as great a fall in plasma osmolality nor did it increase UPGEV. These data indicate that renal prostaglandin synthesis (as determined by UPGEV) is increased transiently by an acute water load; dDAVP given during continued water ingestion results in a fall in plasma osmolality and increased PGE excretion; however, dDAVP does not increase UPGEV during normal hydration; and UPGEV is independent of changes in urine flow. These findings imply that renal prostaglandins may have a functional role in humans to inhibit the hydroosmotic actions of antidiuretic hormone, and thus hasten the excretion of a water load, and to prevent overhydration when inappropriate antidiuresis occurs. However, there is no evidence that the stimulus for prostaglandin production is dDAVP per se.

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