Topic
Tonicity
About: Tonicity is a research topic. Over the lifetime, 1170 publications have been published within this topic receiving 35606 citations. The topic is also known as: hypertonic.
Papers published on a yearly basis
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Papers
TL;DR: Water diuresis is fitly and accurately described as a condition of physiological diabetes insipidus, the antidiuretic secretion of the neuro-hypophysis being a hormone in the sense that its liberation is continually governed by the concentration of sodium chloride, and of other osmotically active substances, in the arterial plasma.
Abstract: When water is given under specified conditions to the living dog, there is a lag of 15 min. between the peak of the animal's water load and the maximum rate of water excretion by the kidney. The diuresis is inhibited by emotional stress, the inhibition being of post-pituitary origin and itself suppressed by an immediately preceding injection of adrenaline or tyramine. Reasons are given for the view that this action of adrenaline is independent of any accompanying increase in arterial pressure or cerebral blood flow. The intracarotid injection (short period, 5 to 20 sec.) of 'hypertonic' solutions of sodium chloride (but not of urea) causes a similar inhibition, the response being diminished by some 90% after removal of the posterior lobe. The response to sodium chloride is shown to be osmotically determined, and the term 'osmoreceptors' has therefore been introduced as descriptive of the autonomic receptive elements with which the neurohypophysis is functionally linked. The receptors are somewhere in the vascular bed of the internal carotid artery. The results of long-period (10 and 40 min.) intracarotid infusions and of the short-period injections, show that the osmoreceptors are freely permeable to urea, less freely permeable to dextrose and relatively impermeable to sodium chloride and sucrose. The local increase in osmotic pressure required in the 40 min. infusions (unilateral) to reduce the urine flow during water diuresis to about 10% of its maximum, is some 2% only; and assay of such response shows it to have a post-pituitary extract equivalence of $1\mu \text{U/sec.}$ $(0.5\times 10^{-9}$ $\text{g./sec.}$ in terms of the standard powder). These facts give an intelligible interpretation to the time-lag between the peak of the water load and the peak of diuresis. Water diuresis, therefore, is fitly and accurately described as a condition of physiological diabetes insipidus, the antidiuretic secretion of the neurohypophysis being a hormone in the sense that its liberation is continually governed by the concentration of sodium chloride, and of other osmotically active substances, in the arterial plasma.
1,057 citations
TL;DR: The hypothesis is presented that ischemic swelling of cells may occlude small blood vessels so that recirculation does not resume even after the initial cause of the ischemia is no longer present, and solutes which do not penetrate cell membranes are able to shrink swollen cells, increase the available vascular space and thus permit reflow of blood to the isChemic organ.
Abstract: The failure of blood flow to return to the kidney following a transient period of ischemia has long been recognized. The cause of this "no-reflow" has been investigated in the rat after a transient period of total obstruction of the renal arteries. The vascular pattern of the kidneys as visualized with silicone rubber injection shows a diffuse patchy ischemia throughout the kidney, which persists after release of the obstructed renal artery. Electron microscopic studies of ischemic kidneys showed that all cellular elements were swollen and limiting the available vascular space. Functional studies revealed an increase in plasma urea nitrogen and creatinine after 1 hr or longer ischemic periods. The ischemia, cell swelling, "no-reflow," and subsequent renal dysfunction occurring after obstruction to the renal arteries were corrected by the administration of hypertonic mannitol, but were unaffected by an equivalent expansion of the extracellular fluid volume either with isotonic saline or isotonic mannitol, showing that the osmotic effect was primary. The hypothesis is presented that ischemic swelling of cells may occlude small blood vessels so that recirculation does not resume even after the initial cause of the ischemia is no longer present; solutes which do not penetrate cell membranes are able to shrink swollen cells, increase the available vascular space and thus permit reflow of blood to the ischemic organ.
460 citations
TL;DR: In experimental animals, the osmotic method has been used to grant wide access to the brain of water-soluble drugs, peptides, antibodies, boron compounds for neutron capture therapy, and viral vectors for gene therapy.
Abstract: 1. Osmotic opening of the blood-brain barrier by intracarotid infusion of a hypertonic arabinose or mannitol solution is mediated by vasodilatation and shrinkage of cerebrovascular endothelial cells, with widening of the interendothelial tight junctions to an estimated radius of 200 A. The effect may be facilitated by calcium-mediated contraction of the endothelial cytoskeleton. 2. The marked increase in apparent blood-brain barrier permeability to intravascular substances (10-fold for small molecules) following the osmotic procedure is due to both increased diffusion and bulk fluid flow across the tight junctions. The permeability effect is largely reversed within 10 min. 3. In experimental animals, the osmotic method has been used to grant wide access to the brain of water-soluble drugs, peptides, antibodies, boron compounds for neutron capture therapy, and viral vectors for gene therapy. The method also has been used together with anticancer drugs to treat patients with metastatic or primary brain tumors, with some success and minimal morbidity.
440 citations
TL;DR: An analytical methodology has been developed for predicting optimal protocols to reduce osmotic injury associated with the addition and removal of hypertonic concentrations of glycerol in human spermatozoa.
Abstract: Use of a cryoprotective agent is indispensable to prevent injury to human spermatozoa during the cryopreservation process. However, addition of cryoprotective agents to spermatozoa before cooling and their removal after warming may create severe osmotic stress for the cells, resulting in injury. The objective of this study was to test the hypothesis that the degree (or magnitude) of human sperm volume excursion can be used as an independent indicator to evaluate and predict possible osmotic injury to spermatozoa during the addition and removal of cryoprotective agents. Glycerol was used as a model cryoprotective agent in the present study. To test this hypothesis, first the tolerance limits of spermatozoa to swelling in hypo-osmotic solutions (iso-osmotic medium diluted with water) and to shrinkage in hyperosmotic solutions (iso-osmotic medium with sucrose) were determined. Sperm plasma membrane integrity was measured by fluorescent staining, and sperm motility was assessed by computer-assisted semen analysis before, during and after the anisosomotic exposure. The result indicate firstly that motility was much more sensitive to anisosmotic conditions than membrane integrity, and secondly that motility was substantially more sensitive to hypotonic than to hypertonic conditions. Based on the experimental data, osmotic injury as a function of sperm volume excursion (swelling or shrinking) was determined. The second step, using these sperm volume excursion limits and previously measured glycerol and water permeability coefficients of human spermatozoa, was to predict, by computer simulation, the cell osmotic injury caused by different procedures for the addition and removal of glycerol. The predicted sperm injury was confirmed by experiment. Based on this study, an analytical methodology has been developed for predicting optimal protocols to reduce osmotic injury associated with the addition and removal of hypertonic concentrations of glycerol in human spermatozoa.
345 citations
TL;DR: The findings indicate that TRPV4 is present in articular chondrocytes, and chONDrocyte response to hypo-osmotic stress is mediated by this channel, which involves both an extracellular Ca(2+) and intracellular Ca-2+) release.
Abstract: Objective
Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+ permeable channel that can be gated by tonicity (osmolarity) and mechanical stimuli. Chondrocytes, the cells in cartilage, respond to their osmotic and mechanical environments; however, the molecular basis of this signal transduction is not fully understood. The objective of this study was to demonstrate the presence and functionality of TRPV4 in chondrocytes.
308 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 28 |
| 2024 | 48 |
| 2023 | 49 |
| 2022 | 96 |
| 2021 | 16 |
| 2020 | 9 |