PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Water Movements”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2003

Role of aquaporin and sodium channel in pleural water movement.

The role of the ENaC sodium channel and aquaporin-1 (AQP1) water channel on pleural fluid dynamics in mice was investigated. 0.25 ml of hypertonic or isosmolar fluid was infused into the pleural space in anesthetized wildtype and AQP1 null mice. Pleural fluid was sampled at specified times to quantify the osmolality and volume. The sodium channel activator terbutaline increased isosmolar fluid clearance by 90% while the sodium channel inhibitor amiloride decreased it by 15%, but had no effect on osmotically driven water transport. AQP1 deletion significantly decreased osmotic water transport in pleural space by twofold, but it had no effect on isosmolar fluid clearance. Pretreatment with dexamethasone increased pleural osmotic fluid entry by 25%, while intravenous injection of HgCl2 decreased osmotic pleural water movement by 43%. These results provided evidence for a role of a sodium channel in pleural fluid absorption; AQP1 plays a major role in osmotic liquid transport but it does not affect isosmolar fluid clearance.

Amiloride↗
PubMed1975

Effect of secretin on intestinal monosaccharide absorption and new water movement in the rat.

Repeated intravenous injections of 2.0 clinical units (CU) secretin per kg body weight showed no effect on jejunal glucose absorption and net water movement in perfusion studies in vivo. The in vitro uptake of galactose and 3-O-methylglucose was not altered by a secretin load given 12 min before sacrifice. The values for Km and Vmax were identical after secretin and in a control group. The conflicting results of different authors concerning the effect of secretin on net water movement and solute absorption may be due to differences in experimental techniques, different, mostly pharmacological doses of the hormone, and a diverse response of heterogeneous species.

Animals↗
PubMed1977

The function of prostaglandins in transmucosal water movement and blood flow in the rat jejunum.

1. Jejunal loops of anaesthetized rats were perfused with isotonic buffer containing PGE1, PGF2alpha or indomethacin. Intestinal blood flow, absorption and secretion of tritiated water were measured. 2. PGE1 at the low concentration of 0.1 microgram ml-1 did not influence intestinal blood flow but increased secretion and decreased absorption of tritiated water. In higher concentrations (0.5 and 6.5 microgram ml-1), blood flow, secretion and absorption were enhanced. 3. PGF2alpha, even in the high concentration of 50 microgram ml-1, did not influence intestinal blood flow but enhanced secretion and decreased absorption of tritiated water. 4. Indomethacin (1 microgram ml-1) decreased intestinal blood flow and secretion but enhanced absorption of tritiated water. 5. The effects of indomethacin on blood flow can be prevented and those on secretion can be even reversed by an additional infusion of PGE1 (0.5 microgram ml-1). 6. PGs appear to play a physiological role in the regulation of intestinal blood flow and transmucosal water movement, since inhibition of endogenous PG synthesis by indomethacin results in effects opposite to those of intraluminally applied PGE1. The results obtained with the low concentration of PGE1 (0.1 microgram ml-1) and with PGF2alpha (50 microgram ml-1) strongly indicate that intestinal water movement can be changed independently of intestinal blood flow.

Animals↗
PubMed1982

Effect of cetiedil on cation and water movements in erythrocytes.

Cetiedil is a potential antisickling agent whose major effect appears to be at the erythrocyte membrane. To test the hypothesis that cetiedil alters cation transport, we studied the effect of the drug in promoting changes in cell water (Wc), cell sodium (Nac), and cell potassium (Kc). Results are quite different depending on the presence or near absence of intracellular ATP. With fresh cells, 100 microM cetiedil causes little in the net cation or water movements compared with control cells incubated for 2 h. At cetiedil concentrations greater than 100 microM, however, net movements of sodium and potassium increase considerably, and cell swelling results from a net Nac gain that exceeds a net Kc loss. All water movements can be accounted for by cetiedil-induced net cation movements. When 100 microM ouabain is added along with cetiedil, net Nac gain, net Kc loss, and net Wc gain are all increased compared with results obtained with cetiedil alone. External calcium inhibits cetiedil-induced changes in cation transport. With cells depleted of their ATP, cetiedil inhibits the typical potassium loss that occurs in the presence of external calcium; net sodium uptake changes little under these conditions, regardless of the presence or absence of external calcium. Our findings indicate a complex mode of action for cetiedil on the erythrocyte membrane, and support the hypothesis that the erythrocyte membrane, and support the hypothesis that the antisickling effect of the drug observed in vitro results from dilution of intracellular hemoglobin secondary to net salt and water gain.

Adenosine Triphosphate↗
PubMed1990

Water movement in yellow-cedar seedlings and rooted cuttings: comparison of whole plant and root system pressurization methods.

One-year-old yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) seedlings and rooted cuttings were taken from cold-storage facilities and grown in aerated water in a controlled environment room for 21 days. Root areas of seedlings and rooted cuttings were initially comparable, but after 21 days seedlings had produced more than twice as much new root area as rooted cuttings. Water flow resistance through the plant-atmosphere continuum decreased in both stock types over the 21-day period. In both seedlings and rooted cuttings, transpirational flux density increased in a curvilinear manner as new root area increased. Root resistance to water movement decreased sharply with increasing new root area up to 20 cm(2) in both seedlings and rooted cuttings. Further increases in new root area did not result in further changes in root resistance of either stocktype. Plant water movement was measured by both the whole plant and the root system pressurization methods with results differing between the two techniques.

Journal Article↗
PubMed1976

Model of solute and water movement in the kidney.

Finite difference equations describing salt and water movement in a model of the mammalian kidney have been solved numerically by an extension of the Newton-Raphson method used for the medullary counterflow system. The method permits both steady-state and transient solutions. It has been possible to simulate behavior of the whole kidney as a function of hydrostatic pressures in renal artery, vein, and pelvis; protein and other solute concentrations in arterial blood; and phenomenological equations describing transport of solute and water across nephron and capillary walls. With the model it has been possible to compute concentrations, flows, and hydrostatic pressures in the various nephron segments and in cortical and medullary capillaries and interstitium. In a general way, calculations on the model have met intuitive expectations. In addition, they have reemphasized the critical dependence of renal function on the hydraulic and solute permeabilities of glomerular, postglomerular, and medullary capillaries. These studies provide additional support for our thesis that the functional unit of the kidney is not the single nephron, but a nephrovascular unit consisting of a group of nephrons and their tightly coupled vasculature.

Blood Pressure↗
PubMed1984

Water movement from intracristal spaces in isolated liver mitochondria.

When analyzing mitochondria isolated in a sucrose medium that had been embedded for thin sectioning according to one low denaturation embedding technique, large intracristal spaces were present in close to 90% of the mitochondria. The two crista membranes were closely apposed in only 40% of all cristae. When the mitochondria were transferred to an incubation medium, the percentage of mitochondria with intracristal spaces was reduced to 40%. About 90% of all cristae were lacking any space separating the two crista membranes. The presence of inorganic phosphate in the medium was required for the closing of the intracristal spaces. The percentage of cristae lacking an intracristal space remained the same after addition of substrate for respiration (state 4) and of ADP (state 3). Inhibition or uncoupling of respiration led to an increase in the percentage of intracristal spaces, showing that oxidative phosphorylation is required to maintain the crista membranes closely apposed. The appearance and disappearance of the intracristal spaces was an indication of water movements across the crista membranes. The mean volume of the mitochondria increased 33% when they were transferred from the sucrose medium to the incubation medium, showing that the removal of water from the cristae was not caused by a passive osmotic effect. Addition of substrate made the volume decrease by 28%. After further addition of ADP, the volume decreased another 23%. No change in volume was associated with inhibition or uncoupling of respiration. The observations revealed that water can move into or out of the cristae independently of water movement out from the entire mitochondrion. Therefore, the water moving out from or into the cristae is translocated across the cristae membrane. The observations are interpreted to reveal the presence of a mechanism that actively prevents water from accumulating in the crista membrane. This mechanism allows for a low water activity to be maintained within the membrane. The variations in the frequency of intracristal spaces occurred without any simultaneous changes in the width of the space appearing between the two surface membranes after isolation of the mitochondria. The observations, therefore, do not agree with the concept that there is an outer compartment that communicates freely with intracristal spaces.

2,4-Dinitrophenol↗
PubMed1976

Regional ileitis (Crohn's disease). II. Electrolyte and water movement in the ileum during perfusion with bile acids.

Electrolyte and water movement was studied by steady state perfusion technique in the ileum of 11 patients with regional ileitis (Crohn's disease). Six patients who at the time of investigation had diarrhoea showed a constant secretion of salts and fluid during perfusion with control perfusate. Per 24 hours, the ileal effluents to colon would exceed the normal amount by 1-2 litres. In the 5 patients without diarrhoea the absorption patterns were normal. Electrolytes and water moved in parallel. Dihydroxy bile acids enhanced secretion or decreased absorption respectively, in the two groups of patients. It is concluded that functional disturbances of salt and water absorption in the inflamed ileum may be of significant physiological importance in the pathogenesis of diarrhoea observed in patients with regional ileitis.

Adult↗
PubMed1996

Noninvasive analysis of water movement in rat testis using deuterium magnetic resonance imaging.

To measure water movement in the testis without the effects from the blood-testis barrier, we performed in vivo deuterium magnetic resonance imaging (2H MRI) of rats administered with deuterated saline. Alcohol was injected into one testis of each animal and the other was administered with normal saline as a control. Dynamic 2H MRI was obtained at 2 T by FLASH pulse sequence (TR, 300 ms; TE, 10 ms; alpha = 90 degrees) using a surface coil (3 cm in diameter). The variation in 2H signal intensity between the two testes as a function of time after deuterated saline injection was examined every 1.1 min up to 20 min. The signal intensity in the testis receiving the alcohol treatment was lower than that in the normal control. Thus, deuterium MRI can be used to analyze functional disorders of the testis.

Animals↗
PubMed1989

Water movement: does thermodynamic interpretation distort reality?

In a recent theoretical analysis of water flow, Finkelstein (Water Movement Through Lipid Bilayers, Pores, and Plasma Membranes: Theory and Reality, 1987) has attacked the contributions of irreversible thermodynamics, stating that "the thermodynamic treatment of uphill water flow completely distorts reality." Instead he presents a mechanistic formulation. For a porous membrane, water flow is attributed to convection generated by a favorable hydrostatic pressure gradient within pores, even when in the presence of permeant solutes water moves against its chemical potential gradient; water flow may "drag", solute, to an extent determined by the solute partition coefficient, but the possibility that solute flow may drag water is excluded. We argue that this formulation violates the second law of thermodynamics. Water cannot move against its chemical potential gradient because of the influence of only part of the chemical potential gradient. Furthermore, the proposed mechanism requires that at one of the membrane-solution interfaces water must move against both its concentration gradient and the hydrostatic pressure gradient. Also considered by Finkelstein is the nature of the reflection coefficient sigma, a kinetic variable, which he concludes can be evaluated (in a porous membrane) by measurement of the (equilibrium) solute partition coefficient. We claim that in general it is not possible to evaluate a kinetic variable from measurements of equilibrium parameters alone. A valid kinetic analysis must incorporate the contribution of all coupled flows.

Body Water↗
PubMed1977

Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport.

Catecholamines induce net salt and water movements in duck red cells incubated in isotonic solutions. The rate of this response is approximately three times greater than a comparable effect observed in 400 mosmol hypertonic solutions in the absence of hormone (W.F. Schmidt and T. J. McManus. 1977 a.J. Gen. Physiol. 70:59-79. Otherwise, these two systems share a great many similarities. In both cases, net water and salt movements have a marked dependence on external cation concentrations, are sensitive to furosemide and insensitive to ouabain, and allow the substitution of rubidium for external potassium. In the presence of ouabain, but the absence of external potassium (or rubidium), a furosemide-sensitive net extrusion of sodium against a large electrochemical gradient can be demonstrated. When norepinephrine-treated cells are incubated with ouabain and sufficient external sodium, the furosemide-sensitive, unidirectional influxes of both sodium and rubidium are half- maximally saturated at similar rubidium concentrations; with saturating external rubidium, the same fluxes are half-maximal at comparable levels of external sodium. In the absence of sodium, a catecholamine-stimulated, furosemide-sensitive influx of rubidium persists. In the absence of rubidium, a similar but smaller component of sodium influx can be seen. We interpret these results in terms of a cotransport model for sodium plus potassium which is activated by hypertonicity or norepinephrine. When either ion is absent from the incubation medium, the system promotes an exchange-diffusion type of movement of the co-ion into the cells. In the absence of external potassium, net movement of potassium out of the cell leads to a coupled extrusion of sodium against its electrochemical gradient.

Animals↗
PubMed1991

Transepithelial water movement in response to carbamazepine, chlorpropamide and demeclocycline in toad urinary bladder.

1. Osmotic water movement across toad isolated hemibladders was measured by a gravimetric method. 2. The influence of carbamazepine, chlorpropamide and demeclocycline on the antidiuretic hormone (ADH)-induced water flow rate was examined. 3. No antidiuretic activity due to carbamazepine alone was observed but a slight inhibition due to ADH-induced water flow was observed in the presence of carbamazepine over a selected dose-range. This was unexpected and is inconsistent with data from in vivo studies in man. 4. Chlorpropamide potentiated ADH-induced water flow, in keeping with the hypothesis that chlorpropamide sensitizes the renal tubules to ADH-induced water flow. 5. Demeclocycline inhibited ADH-induced water flow. The mechanism of action remains unclear.

Animals↗
PubMed1961

The relation of oxygen supply to water movement and to urea formation in surviving liver tissue.

Liver slices have been immersed during periods up to 4 hours at 38 degrees C. in Krebs-Ringer solution with bicarbonate buffer and exposed to varied oxygen supply in the presence of carbon dioxide equal to that of venous blood. Water movement, urea, and amino acid formation by the liver tissue have been measured. Water contents of surviving liver tissue diminishes with increased oxygen supply, but during life the maximum limit of oxygen is determined by that brought by the arterial blood and has an approximate partial pressure of 100 mm. Hg. Urea formation by liver slices is increased by increased oxygen supply but does not occur with anoxia. Osmotic pressure within liver cells is maintained in part by amino acids and related substances, and in part by electrolytes. Diminished osmotic pressure and loss of water is explainable by oxidation of nitrogenous substances with formation of urea which leaves the cells. These changes within a limited range of variation are adjustable to functional needs.

Amino Acids↗
PubMed1981

Dependence of water movement on sodium transport in kidney proximal tubule: a microperfusion study substituting lithium for sodium.

The relationship between water and sodium movements through the mammalian proximal convoluted tubule was investigated by substituting lithium for sodium. Proximal convoluted rat Kidney tubules were perfused in vivo with a Ringer solution containing 107 meq/liter lithium and 42 meq/liter sodium. Several micropunctures were made along the same nephron, and [3H] inulin, [14C] glucose, 22Na, osmolality, Na, Mg and Cl were determined on each sample. Measurements of 22Na showed that sodium and lithium diffusion rates were practically identical throughout the entire epithelium. A one- for-one exchange of sodium for lithium induced a negative transepithelial net flux of Na from plasma to lumen. However, despite this negative flux, a positive net water movement was measured from lumen to plasma. This movement was proportional both to glucose reabsorption and to the rise in the chloride concentration, two mechanisms known to be dependent on the transcellular movement of sodium. It was therefore concluded that the net water flux was a function of the unidirectional transcellular net flux of Na. Rabbit proximal convoluted tubules were perfused in vitro with solution containing 75 meq/liter Li and 75 meq/liter Na on both the luminal and peritubular sides. Under these conditions, the water reabsorption rate dropped to half its control value. Water movement was therefore a function of the external sodium concentration, which in turn probably regulates the intracellular Na concentration.

Animals↗
PubMed1985

Carrier-mediated KCl accumulation accompanied by water movements is involved in the control of physiological K+ levels by astrocytes.

Potassium accumulation and water transport into mouse astrocytes in primary cultures were investigated when external potassium was increased from 3 to 12 mM. The intracellular potassium content increased by 63% within 50 s of such a change. The increase consisted of a ouabain- and furosemide-sensitive component, both contributing in about the same amounts. Experiments with altered ion composition revealed that the furosemide-sensitive component consisted of a KCl accumulation. Water moved into the astrocytes without delay after such an external K+ increase and increased the cell water by 27%. This water increase was abolished in solutions with reduced Cl- and during application of furosemide. Thus, these results on a KCl uptake accompanied by water movements into astrocytes suggest a potential mechanism by which glial cells in situ can regulate external K+ levels.

Animals↗
PubMed1979

An analysis of water movement between myocardial tissue and capillary blood during reactive hyperemia.

The colloid osmotic pressure (COP) of blood from the great cardiac vein was continuously measured by means of a membrane colloid osmometer during the reactive hyperemia following temporary occlusion of the anterior descending branch of the left coronary artery in anesthetized open-chest dogs. The COP increased sharply after releasing the occlusion, then decreased below the preocclusion level before gradually returning to it. These findings indicate that a measurable amount of water moved from the capillary blood into the myocardial tissues and then flowed back slowly into the capillary blood. To analyse the factors affecting this water movement, a method is proposed in which the Starling mechanism is combined with the interstitial volume elasticity and a steady-state solution of a Navier-Stokes equation. The pressure observed with a catheter wedged into a branch of the great cardiac vein was used as a measure of capillary perfusion pressure. During the coronary arterial occlusion, the filtration constant increased while the volume elasticity of the myocardial interstitial spaces decreased rapidly. The filtration constant and volume elasticity of the interstitial space under normal conditions were approximately estimated to be 2.4 X 10(-11) cm/(sec.dyn.cm-2) and 1.1 X 10(7) dyn.cm-2, respectively.

Animals↗
PubMed2006

Parenchyma-chlorenchyma water movement during drought for the hemiepiphytic cactus Hylocereus undatus.

BACKGROUND AND AIMS: Hylocereus undatus, a hemiepiphytic cactus cultivated in 20 countries for its fruit, has fleshy stems whose water storage is crucial for surviving drought. Inter-tissue water transfer during drought was therefore analysed based on cell volumes and water potential components. METHODS: In addition to determining cell dimensions, osmotic pressures and water potentials, a novel but simple procedure leading to an external water potential of zero was devised by which cells in thin sections were perfused with distilled water. The resulting volume changes indicated that the parenchyma-chlorenchyma water movement was related to more flexible cell walls in the water-storage parenchyma with its lower internal turgor pressure (P) than in the chlorenchyma. KEY RESULTS: Under wet conditions, P was 0.45 MPa in the chlorenchyma but only 0.10 MPa in the water-storage parenchyma. During 6 weeks of drought, the stems lost one-third of their water content, becoming flaccid. About 95 % of the water lost came from cells in the water-storage parenchyma, which decreased by 44 % in length and volume, whereas cells in the adjacent chlorenchyma decreased by only 6 %; the osmotic pressure concomitantly increased by only 10 % in the chlorenchyma but by 75 % in the water-storage parenchyma. CONCLUSIONS: The concentrating effect that occurred as cellular volume decreased indicated no change in cellular solute amounts during 6 weeks of drought. The ability to shift water from the parenchyma to the chlorenchyma allowed the latter tissue to maintain a positive net CO2 uptake rate during such a drought.

Biological Transport↗