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PubMedDate not supplied

[Adaptive evolution of osmoregulation in rodents with different ecologies].

Studies have been made on osmoregulation in aquatic rats (Arvicola terristris), cotton rats (Sigmodou hispidus) and Wistar albino rats under the conditions of usual salt-water regimen and 3-day water deficiency. In water-loving rodents, water deficiency results in significant changes in blood constants which charasterize osmotic homeostasis (sodium and urea concentration, the osmolarity). In albino rats, the state of dehydration is accompanied by a significant increase in antidiuretic activity of the blood serum and by an increase in osmotic concentrating index up to 7.4 +/- 0.2. In A. terestris and S. hispidus, despite of the increase in antidiuretic activity of the blood serum, no significant increase in U/Posm was found (2.7 +/- 0.2 and 4.8 +/-0.3 respectively). Low effectiveness of osmotic concentration in water-loving rodents is due to structural and functional rearrangement of the concentrating mechanism of the kidney, and, as a result, to the decrease in intrarenal gradients of sodium and urea. These peculiarities determine ecological specialization of osmoregulatory system.

Adaptation, Physiological↗
PubMed2005

[Construction of fused osmoregulation proBA gene from a salt-tolerant mutant of Bacillus subtilis and its influence on the osmotolerance of Escherichia coli].

The osmoregulation proB and proA genes from Bacillus subtilis 93151 are overlapping genes, which encode two proteins ProB and ProA. A restriction enzyme site was inserted in the overlapping region of proB and proA genes from a salt-tolerant mutant of B. subtilis 93151, and a fusion gene was constructed by cloning proB and proA genes respectively. SDS-PAGE analysis showed that a novel protein with molecular mass of 85 kD was observed. When expressed in E. coli, enhanced intracellular concentrations of free proline and osmotolerance of the strain carrying the fusion gene were observed, compared with the control host cell harbouring a plasmid encoding the separate ProB and ProA.

Adaptation, Physiological↗
PubMed2006

[Dynamics of renal medullary vinculin under changing of osmoregulating function].

Reduction of vinculin occurs in the renal medulla under the long-lasting dehydration. The protein content measured in inner medulla of rats of the WAG line under hydration was 92.1 +/- 6.3 in relative units, but it was only 77.6 +/- 2.3 after a 3-day water deprivation. The vinculin content in the inner medullar layer from mutant rats of Brattleboro line incapable of synthesizing vasopressin is essentially higher: it is 188.9 +/- 8.5 in hydrated conditions and drops to 148.4 +/- 7.3 under a 3-day dehydration. The same high level of vinculin is in outer medulla from rats of Brattleboro line: 222.1 +/- 11.8 in hydrated animals and 174.9 +/- 11 after a 3-day dehydration. No differences were revealed in response of vinculin to alternative osmoregulating stimulation in cortex in both rat lines.

Animals↗
PubMed1989

In an Escherichia coli coupled transcription-translation system, expression of the osmoregulated gene proU is stimulated at elevated potassium concentrations and by an extract from cells grown at high osmolality.

We have studied the in vitro expression of the osmoregulated proU promoter in Escherichia coli coupled transcription-translation (S-30) extracts as a function of the osmolality of the culture medium used to grow the cells and of the salt concentration added to the extract. These variables represent novel extensions of the use of S-30 extracts to investigate gene regulatory phenomena in vitro. The concentrations of potassium acetate and of the physiologically relevant osmolyte potassium glutamate for maximal expression of the proU promoter are approximately 2-fold higher than the concentrations of these salts providing maximal expression of the lacUV5 promoter. The relative promoter activity of proU with respect to lacUV5 increases more than 30-fold with an increase in salt concentration from 50 to 300 mM. In comparative studies with S-30 extracts prepared from cells grown at high and low osmolalities, we find that at fixed salt concentrations expression of proU is increased 10-fold in the S-30 extract prepared from high osmolality-grown cells, whereas the expression of lacUV5 is increased less than 2-fold. Addition of anti-sigma 70 monoclonal antibodies or purified sigma 70 to the S-30 extract demonstrated that the major proU promoter(s) used in the S-30 extracts is sigma 70-dependent.

Acetates↗
PubMed1987

Dipsogenic diabetes insipidus: a newly recognized syndrome caused by a selective defect in the osmoregulation of thirst.

We describe three patients who have polydipsia and polyuria due to an abnormality in the osmoregulation of thirst. The clinical manifestations of the syndrome are similar to those of neurogenic diabetes insipidus. Thus, under basal conditions the patients have thirst, normal to high normal levels of plasma osmolality, and low levels of plasma vasopressin. Moreover, antidiuretic therapy greatly reduces thirst and polydipsia as well as polyuria. The only clinically distinguishing feature of the response is that thirst and water intake decrease less rapidly than water excretion. As a consequence, the patients with this syndrome develop variable degrees of dilutional hyponatremia and hypoosmolemia during treatment. The plasma vasopressin response to osmotic stimulation is relatively normal. In most of the patients, the osmotic threshold for vasopressin release is at the upper limit of normal, but this finding only explains their modest elevation in basal plasma osmolality. Thirst and water intake also change as a function of plasma osmolality. However, the threshold or "set" of the thirst osmostat appears to be abnormally low. The degree of downward resetting varies from patient to patient, but is always sufficient to stimulate thirst and water intake at levels of plasma osmolality below the normal range. This abnormality can account not only for the thirst and polyuria under basal conditions but also for the overhydration that occurs during antidiuretic therapy. The pathogenesis of the osmoregulatory abnormality is unknown but may be due to disruption of one or more of the afferent pathways that regulate the "set" of the thirst and vasopressin osmostats.

Adult↗
PubMedDate not supplied

[The role of heat shock proteins in the osmoregulation of Escherichia coli].

E. coli has a number of biochemical systems which protect cells from different chemical and physical damages. The aim of this work is to characterize the interaction between two of these: the osmoregulation system and the heat shock system. It is shown that exposure of E. coli to 42 degrees C to induce hsps synthesis, abolish the growth inhibition by high (0.45 M) NaCl concentration. Also, transient pretreatment of cells with high NaCl protect them from heat damage. It is shown that osmotic shock induces the hsps synthesis. The cell growth restoration after the complete inhibition by high (0.6 M) NaCl concentration correlates with the hsps accumulation. Moreover the heat shock treatment reduces the adaptation time.

Escherichia coli↗
PubMed1984

Osmoregulation in a parasitic nematode, Setaria cervi.

Studies on osmotic and ionic regulation in Setaria cervi indicate that it can osmoregulate in hypertonic solutions but not in hypotonic solutions. The depression of the freezing point (delta degrees C) of host's peritoneal fluid was -0.71 degrees C.

Animals↗
PubMed1980

Is the weight loss of hyperbaric habitation a disorder of osmoregulation?

To examine the weight loss of hyperbaric helium-oxygen habitation, we measured the exchange of liquids and calories in six men who lived in this atmosphere for 32 d. The maximum pressure was 49.5 ATA. The men lost 3.7-10.1 kg, in spite of warm ambient (31-32 degrees C) temperatures and adequate calories (2,737 kcal/d) provided for the sedentary ways of chamber living. Weight loss and a calculated fluid deficit were accompanied by significant hemoconcentration, shown by increases in serum proteins. These changes were followed by a rise in urinary aldosterone and vasopressin, but not thirst. Weight loss in hyperbaric atmospheres is probably multifactorial, but our data suggests an uncoupling of normal osmoregulation may have occurred in the present set of subjects. This may have been due to altered lung mechanics, increased catecholamines, or effects of high pressure on cellular responses to vasopressin.

Aldosterone↗
PubMed1998

FMRFamide-related peptides, partial serotonin depletion, and osmoregulation in Helisoma duryi (Mollusca: Pulmonata).

Serotonergic neurons were studied by specific histological methods, and neurons containing Phe-Met-Arg-Phe-NH2 (FMRFamide)-related heptapeptides were identified with an antiserum specific for these substances in the central nervous system of the freshwater snail Helisoma duryi. Serotonergic neurons and their axons are present in all of the ganglia (paired buccal, cerebral, pedal, pleural, parietal, and single visceral) and major nerves of the central nervous system. Large neurons containing FMRFamide-related peptide immunoreactivity are located in the left parietal and visceral ganglia, whereas a few small neurons are located in the cerebral and pedal ganglia. Both serotonergic and FMRFamide-related peptide-immunoreactive dendrites and varicosities were observed in the kidney. A second antiserum with high affinity for FMRFamide-related heptapeptides was used to measure the levels of the immunoreactive material in various tissues, and such material was found in every tissue analyzed. When snails were exposed to a medium isosmotic to their hemolymph, the levels of immunoreactive FMRFamide-related peptides increased in the hemolymph, central nervous system, mantle, and kidney. Injection of dihydroxytryptamine, which is known to deplete serotonin content in the snail, also reduced the levels of FMRFamide-related-immunoreactive material in the above tissues. Therefore, serotonin may influence the levels of FMRFamide-related peptides in tissues by regulating the rate of their synthesis, axonal transport, or release. Both serotonin and FMRFamide-related peptides could be involved in osmoregulation.

5,6-Dihydroxytryptamine↗
PubMedDate not supplied

[The participation of the gastrointestinal tract of desert rodents in osmoregulation].

Studies have been made on the levels of Na, K and water in the content of rectum and blind gut of the albino rat Rattus norvegicus and gerbils Rhombomys opimus, Meriones tamariscinus and M. meridianus under conventional water and salt supply and during prolonged water deprivation of animals. It was shown that under conventional conditions, the content of water, Na and K in the chymus of the blind gut is higher in gerbils than in rats. After 7-day dehydration in rats, the body weight decreased by 26.4 +/- 0.8%, the level of water in gut composition remained unchanged, whereas Na and K concentrations increased. In gerbils, 25 days after water deprivation, the loss of the body weight was equal approximately to 20%, Na concentration in rectal content decreased or remained unchanged, whereas K and water decreased. Possible role of gastro-intestinal tract in osmoregulation of desert rodents is discussed.

Animals↗
PubMed1998

[Acquired disorder of thirst perception with intact osmoregulation of vasopressin].

We report a 45 y old male patient with severe hypodipsia, but intact vasopressin secretion and maximal renal response to vasopressin. The patient presented during hot summer days, 18 months after a frontal lobe hemorrhage due to a ruptured aneurysm, with severe hypernatremia (171 mmol/L) and a plasma osmolality of 348 mosm/kg. He was awake and had no interest in fluid intake. After initial correction, a thirst test for 36 hours was performed. Plasma osmolality rose from 295 to 320, urine osmolality rose from 220 to 700 mosm/kg, while plasma vasopressin levels increased more than 3-fold. Throughout the test the patient did not exhibit appreciable thirst. The intact osmoregulation of vasopressin as evidenced by the plasma levels and the elicited renal response, indicates that a selective acquired disturbance of thirst is present. Whether the thirst center is destroyed or/and thirst recognition (frontal lobe affection) is disturbed primarily, can not be decided.

Aneurysm, Ruptured↗
PubMed1998

Osmoregulation in clinical disorders of thirst appreciation.

Thirst and drinking are essential components of normal osmoregulation in healthy man. Abnormalities of thirst appreciation, in particular hypodipsia, have profound implications for water homeostasis. The combination of cranial diabetes insipidus and hypodipsia can have particularly serious consequences, with the potential for life-threatening hyponatraemia. Although the tools for measuring thirst are subjective and lack true specificity, their use in clinical research has contributed greatly to our understanding of the physiology of thirst appreciation and the abnormal control of thirst in osmoregulatory disorders. The precise neural control of thirst appreciation remains unknown, and perhaps as a result of this, satisfactory therapies for the treatment of disorders of thirst have not yet been developed; behavioural modification and retraining of drinking habits remain the rather limited cornerstones of management.

Adult↗
PubMed2026

Transcriptomic and RNAi analyses reveal chloride channel 3-associated osmoregulation in Litopenaeus vannamei under low-salinity stress.

Chloride channels and transporters are important for cellular volume regulation and salinity adaptation in euryhaline crustaceans, yet the intestinal transcriptional relationship between plasma-membrane and intracellular chloride pathways remains unclear in Litopenaeus vannamei. In this study, RNA interference of anoctamin 1 (ANO1) was combined with intestinal transcriptome sequencing under the production-relevant low-salinity condition of salinity 3. ANO1 silencing produced a focused transcriptional response, with 16 differentially expressed genes (DEGs) identified (11 upregulated and 5 downregulated). Functional enrichment indicated that these genes were associated with transporter activity, cytoskeletal organization, extracellular matrix-receptor interaction, membrane lipid metabolism, and vesicular processes. Notably, a transcript encoding chloride channel protein 3 (CLC-3) was significantly upregulated following ANO1 knockdown, suggesting a potential transcriptional relationship between ANO1 and CLC-3 in chloride homeostasis. Based on this finding, CLC-3 was selected for full-length cDNA cloning, sequence characterization, salinity-gradient expression analysis, and RNAi-based functional assessment. The cloned CLC-3 cDNA was 2883 bp in length and encoded an 850 amino acid protein containing a conserved voltage-gated chloride channel (Voltage-CLC) domain and two cystathionine β-synthase domains. Phylogenetic analysis placed LvCLC-3 within the intracellular CLC-c clade, and tissue distribution analysis showed the highest CLC-3 expression in the intestine. Intestinal CLC-3 expression responded nonlinearly to salinity variation, peaking at salinity 20. Under salinity 3, CLC-3 knockdown reduced ANO1, Na+/K+-ATPase alpha subunit, and Na+-K+-2Cl- cotransporter transcript levels, whereas glutamate-gated chloride channel expression increased. Mild hepatopancreatic structural alterations were also observed after CLC-3 knockdown. These findings suggest that CLC-3 is a salinity-responsive intracellular chloride-transporter candidate associated with intestinal ion-transport-related transcriptional responses after ANO1 suppression in L. vannamei, although the underlying physiological mechanism requires further validation.

Animals↗