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PubMed1963

FINE STRUCTURE OF CHLORIDE CELLS FROM THREE SPECIES OF FUNDULUS.

A MORPHOLOGICAL BASIS FOR OSMOREGULATION IN THE TELEOSTS WAS STUDIED BY COMPARING THE FINE STRUCTURE OF CHLORIDE CELLS FOUND IN EPITHELIA OF THE GILLS OF THREE SPECIES OF FISH: Fundulus heteroclitus which can survive in a wide range of salinities, and F. similis and F. chrysotus which are usually restricted to salt water and fresh water environments, respectively. Gills were removed from F. heteroclitus which had been laboratory adapted to either sea water or pond water. For a comparison, gills were also removed from the marine F. similis and the fresh water F. chrysotus which had been adapted to their natural environments. Gill-filaments were fixed in Millonig's phosphate buffered (pH 7.4), 1 per cent osmium tetroxide and were embedded in Epon. Thin sections of filaments were stained with lead hydroxide. The cytoplasm of chloride cells of all three species of Fundulus is heavily populated with mitochondria and is filled with tubules of the agranular endoplasmic reticulum (ER). An orderly secretory cycle was indicated for chloride cells of salt water adapted F. heteroclitus and the marine F. similis. An amorphous material is observed in the agranular ER. Its density increases towards the apical end of the cell. In the apical cytoplasm, tubules of the agranular ER appear to converge and to discharge the amorphous material into an apical cavity. Except for the actual opening of the apical cavity, the distal end of salt water adapted chloride cells is characteristically shielded from the hypertonic environment by thin cytoplasmic flanges projecting from the neighboring epithelial cells. Chloride cells of the fresh water F. chrysotus resemble chloride cells of pond water adapted F. heteroclitus, in that these cells do not have apical cavities with the functional appearance of those in the sea water adapted forms. The distal end of fresh water adapted chloride cells is typically exposed to the free surface of the gill-filament. The possible function of the cell type is discussed.

Adaptation, Biological↗
PubMed1963

PHOTOMETRIC EVIDENCE FOR THE OSMOTIC BEHAVIOR OF RAT LIVER MICROSOMES.

Electron microscope observations are consistent with the interpretation that the elements of the endoplasmic reticulum are osmotically active in situ as well as after isolation. More recently, it has been reported that microsomal suspensions equilibrate almost completely with added C(14)-sucrose and that no osmotic behavior is evident from photometric data. These findings were considered at variance with the electron microscope data. However, equilibration with added label simply attests to a relatively high permeability, and, in addition, the photometric data need not be critical. Osmotic volume changes, measured photometrically, may be masked by concomitant events (e.g., changes in the refractive index of the test solutions at varying osmotic pressures, breakdown of the particles, and agglutination). For these reasons the photometric experiments were repeated. In this work, the reciprocal of optical density of microsomal suspensions was found to vary linearly with the reciprocal of concentration of the medium at constant refractive index. These changes probably correspond to osmotic volume changes, since the effect was found to be (a) independent of substance used and (b) osmotically reversible. The transmission of the suspension was found to vary with the refractive index of the medium, the concentration of particles, and the wavelength of incident light, according to relationships that are similar to or identical with those obtained for mitochondrial suspensions.

Animals↗
PubMed1964

OSMOTIC AND METABOLIC ALTERATIONS OF MITOCHONDRIAL SIZE.

Sustained contraction (dehydration) of rat liver mitochondria can be readily produced by increasing the tonicity of the outside media, provided Ca(++) is removed by EDTA, fatty acids are removed by albumin, and a source of chemical energy (mitochondrial substrate or ATP) is present. This was demonstrated both gravimetrically and turbidimetrically. It was also demonstrated that the net movement of sucrose and H(2)O under altered conditions of tonicity in mitochondria was dependent on the state of the mitochondria; e.g., in the presence of EDTA, diffusion was blocked, both into and out of mitochondria, whereas, in the presence of EDTA and electron-transport substrates, movement of sucrose and water out of mitochondria was increased. In the presence of Ca(++), gramicidin, or fatty acids, diffusion of sucrose into and out of mitochondria is very rapid. Mitochondria obey osmotic law only after Ca(++) and fatty acids are removed from them.

Adenosine Triphosphate↗
PubMed1964

ROLE OF EDTA AND METALS IN MITOCHONDRIAL CONTRACTION.

STUDIES COMPARING THE STATE OF HYDRATION AND DEHYDRATION OF RAT LIVER MITOCHONDRIA TO THEIR CONTENT OF ATP, CA, AND FATTY ACID, ALONG WITH THE RATE OF ATP HYDROLYSIS, AS WELL AS MICROSCOPIC APPEARANCE OF MITOCHONDRIA, HAVE LED TO THE FOLLOWING GENERALIZATIONS: 1. The competition between cationic translocations and water translocation for the available chemical energy (ATP) determines under many circumstances the water content of mitochondria. 2. Swelling of mitochondria by electron transport substrates is an example of the activation of the cationic translocations at the expense of water translocation. 3. Electron micrographic studies are interpreted to indicate that EDTA alone can cause condensation and dehydration of the mitochondrial matrix. However, both EDTA and substrate are necessary to remove appreciable quantities of water from mitochondrial intramembranous spaces. 4. Since the data in the accompanying report indicated that EDTA, in the absence of energy, decreased the permeability of mitochondrial membranes, it appears likely that ballooning of intramembranous spaces, following addition of EDTA, represents trapping of water between two semipermeable membranes following dehydration of mitochondrial matrix.

Adenosine Triphosphatases↗
PubMed1954

Osmotic activity of tissues during fetal and post-natal growth.

The osmotic pressure maintained by liver tissue of the white rat preceding birth is less than that of the maternal blood serum and shortly after birth approximates this level. Following birth osmotic pressure of liver tissue, continuing to increase, reaches after about 60 to 90 days the level found in the liver of mature animals and is then isotonic with solutions of sodium chloride with concentration slightly more than twice that isotonic with blood serum. Osmotic pressure maintained by kidney tissue pursues with growth a similar course but at a lower level and about 35 to 60 days after birth reaches that found in the mature animal being represented by isotonicity with a concentration of sodium chloride slightly less than twice that isotonic with blood serum. The tissues of the whole fetus are isotonic with sodium chloride solutions less concentrated than that isotonic with the maternal blood serum.

Animals↗
PubMed1956

Changes in the osmotic activity of liver and of kidney tissue caused by passage of sodium chloride, urea, and some other substances into cells.

The osmotic activity of liver tissue and of kidney cortex tested within 10 minutes after immersion in solutions of sodium chloride has been increased by procedures which introduce sodium chloride, urea or creatinin into the body in excess of its elimination. A substance formed by cell metabolism, namely urea, can increase the osmotic activity of liver and of kidney cells. The amino acids, glycine and arginine, under similar conditions have not increased the osmotic activity of liver or of kidney cortex.

Creatinine↗
PubMed1964

EXPERIMENTAL STUDIES IN ACUTE RENAL FAILURE. II. FINE STRUCTURE CHANGES IN TUBULES ASSOCIATED WITH RENAL FAILURE INDUCED BY GLOBIN.

When purified human globin is injected intravenously into rats it produces acute renal failure characterized by tubular casts and oliguria. The globin is identifiable within vesicles and channels in the cytoplasm of the proximal tubules, through which it passes from lumen to basal side with no apparent serious effect on the cells. When a very minimal amount of globin is taken up by cells of the distal limb of Henle's loop or distal tubules (lower nephron), a markedly deleterious effect is apparent and the cells die within a short time. The mixture of cell debris and precipitated globin forms plugs within the confines of the basement membranes of the former distal limbs and distal tubules. After a number of lower nephrons are plugged a disruption of proximal tubules is found, which apparently results from the effect of back pressure in the obstructed nephrons. We suggest that any amount in excess of a low threshold of globin, either alone or combined with heme or related material, has a toxic effect on lower nephron cells. Once initiated, the toxic effect is not reversible and the resulting plug of debris and precipitate will occlude the lumen. If a sufficient number of nephrons are made non-functional the animal becomes anuric; otherwise it is oliguric. A high rate of urine flow will protect against the excess absorption of material and thus against acute renal failure.

Acidosis↗
PubMed1953

Osmotic homeostasis maintained by mammalian liver, kidney, and other tissues.

Osmotic pressure maintained by liver or kidney tissue measured by its water equilibrium with solutions of sodium chloride remains unchanged from 5 minutes up to 1(1/2) hours following removal of the tissue from the body. Then with autolytic increase of molecular concentration within the cytoplasm of cells it reaches a higher level. Osmotic pressure maintained by pancreas or submaxillary gland, as ascertained in the same way, remains unchanged during (1/2) hour and later increases. Liver tissue of rat, mouse, guinea pig, rabbit, and cat maintains an osmotic pressure greater than twice that of the blood, and kidney tissue maintains an osmotic pressure somewhat less than twice that of blood. Fasting throughout a period of 7 days has little influence upon osmotic pressure maintained by cells of liver or kidney. Low protein diet has been found to depress osmotic pressure of liver cells after about 4 weeks, and with degenerative changes in the parenchyma, notably fatty infiltration, this pressure has remained at a diminished level during approximately 90 days. Increase of pressure within the common bile duct and the changes following biliary obstruction are accompanied by depression of the osmotic pressure maintained by liver tissue and ligation of the ureter diminishes the osmotic pressure maintained by kidney tissue. In both instances osmotic pressure tends later to rise to its former level. The osmotic pressure maintained by liver or by kidney tissue preserves an approximately uniform level under normal conditions and may be little changed by conspicuous injury to the organ. When this osmotic homeostasis is impaired by severe injury the pressure maintained by the tissue returns to its former level with recovery from the injury.

Animals↗
PubMed1950

Ageing and the influx of water into radish root-hair cells.

A micropotometric device previously described by the writer was used to determine quantitatively the velocity of water influx in cubic microns per square micron of hair surface per minute of comparatively older and younger root hairs of radish seedlings in a humid atmosphere at 29 degrees +/- 1 degrees C. when the micropotometers were filled with Hoagland solution at pH 6.8. In each experiment, measurements were made on two hairs of different length and different age on a given root and the hairs were inserted into the micropotometers a sufficient distance so that the area of immersion, 13,200micro(2), was the same in each instance. The range of velocities of water influx through the immersed surface was 4.46 to 1.16micro(3)/micro(2)/min. for the younger and shorter hairs which varied in length from 280 to 460 microns. The range of velocities of water influx through the immersed surface of the older hairs which varied from 661 to 2300 microns in length was 1.94 to 0.47micro(3)/micro(2)/min. The data indicate that water entry slows down in older hairs independent of root length. Estimations were made of the times to replace hair volumes based upon the mean velocities of water entry of the immersed areas. It was found that the time for the hairs to absorb an amount of water equivalent to their own volumes under the conditions specified was a matter of minutes or less; the range was 0.90 to 8.51 minutes.

Hair↗
PubMed1951

The chemical composition and the osmotic pressure of the aqueous humor and plasma of the rabbit.

Measurements were made of the osmotic pressure of plasma, and of aqueous humor taken from the anterior chamber of the right and left eyes and from the posterior chamber of unanesthetized rabbits. Aqueous humor from the anterior chamber was found to be hypertonic to the plasma by approximately 3 mM/liter equivalent of sodium chloride. The aqueous humor from the anterior and posterior chambers of the right and left eyes was isotonic. The concentration of chloride in the anterior and posterior chambers was the same. The concentration of all the major components of the aqueous humor and plasma has been determined by chemical analysis on fluid samples obtained from unanesthetized rabbits at approximately the same time. The calculated osmotic pressure of the total of these substances in terms of sodium chloride equivalent agrees to within better than 1 per cent of the total osmotic pressure as measured experimentally. The distribution of some individual anions and cations of the aqueous humor and plasma was determined. This distribution is widely different from that which would obtain at a state of equilibrium. The positive and negative charges carried by the ions in the aqueous humor were approximately equal. Sources of error in the experiments are discussed.

Animals↗