Net Water Movement Research Articles

Increased water permeability of the bullfrog (Rana catesbiana) bladder in vitro in response to synthetic oxytocin and arginine vasotocin and to neurohypophysial extracts from nomammalian vertebrates.

Ncurohypophysial hormones accelerate the passage of water across the wall of the isolated bullfrog (Rana catesbiana) bladder in vitro. Net water movement may be in either direction depending on the existing osmotic gradient. Net sodium transport from mucosal to serosal surface has little influence on the magnitude or direction of water movement. The increased net water movement is considered, therefore, to be clue to a change in water permeability, probably resulting from the dilatation of pores. Oxytocin is more active than vasopressin in enhancing water permeability. The synthetic analogue arginine vasotocin is many times more active than oxytocin. The ratio of frog-bladder activityto oxytocic activity is high in ncurohypophysial extracts from a lamprey, a teleost, a frog, a toad, a marine turtle, and the chicken. This suggests that arginine vasotocin may be a natural hormone in the neurohypophyses of many non-mammalian vertebrates.

Single proximal tubules of Necturus kidney. IV. Dependence of H20 movement on osmotic gradients.

The relationship between net water flux and osmotic gradients across the Necturus kidney proximal tubule was studied with stopped flow microperfusion technique. To minimize water movement induced by Na transport, perfusion solutions contained 62.5 mm/l. NaCl; at this concentration no net water movement is observed with isosmolar solutions. Mannitol was added to prepare perfusion solutions with gradients ±70 mOs/l. relative to plasma. With these gradients, water movement was symmetrical in both directions across the membrane: tubular volume decreased 46% with hypoosmolar perfusion fluid, and increased 51% with hyperosmolar fluid. The membrane water permeability coefficient, Pf, is 0.15 x 10–8 ml/(cm2 sec. cm H2O). This coefficient permits calculation of net water movement ascribable to plasma protein osmotic pressure. The calculated value is approximately 1% of the fluid normally absorbed by the tubule. This conclusion was confirmed in separate experiments in which albumin was added to perfusion fluid to produce a protein concentration 67% higher than in plasma. Under these conditions, water was still absorbed from the tubule, indicating that proteins do not play a major role in water absorption.

Single proximal tubules of the Necturus kidney. III. Dependence of H2O movement on NaCl concentration.

Stopped flow microperfusion technique ( Am. J. Physiol. 195: 563, 1958) was used to study water movement across the proximal tubular wall of Necturus kidney. In 23 experiments, net water movement was measured from perfusion solutions containing 50, 62.5, 75 and 100 mEq. NaCl/1. which were made isosmotic with Necturus plasma by addition of mannitol. Water movement was shown to depend upon luminal NaCl concentration. Studies of the relationship between net solute flux and water flux demonstrated a linear relationship: net water flux (mµl/sec.) = 9.4 x net solute flux + 0.003. Net water flux is statistically zero when net solute flux is zero. Under these experimental conditions no force is important for water movement other than that arising from solute movement. It is concluded that net movement of Na has taken place up an electrochemical potential gradient, indicating active transport of this ion. Furthermore, movement of water from the tubule is considered to be passive since net water flux may be accounted for quantitatively in terms of osmotically induced forces arising from net solute movement.

Hemorrhagic encephalopathy induced by hypernatremia. I. Clinical, laboratory, and pathological observations.

Hyperosmolarity is characterized by an increase in the solute concentration of body fluids brought about by loss of water, inadequate water intake, or administration of large amounts of hypertonic solutions. When the osmolar concentration of the extracellular fluid is increased, transfer of water from cells to extracellular fluid exceeds that in the opposite direction. Net water movement is thus out of the cells, with resultant dilution of extracellular fluid and concentration of the fluid within cells themselves. If the solute which increases the extracellular fluid osmolarity is one which is in the main excluded from intracellular fluid, such as sodium and chloride ions, this disturbance in water distribution cannot be mitigated by movement of solute into cells. Hence, the ultimate effect of hypernatremia is dehydration of cells. This physicochemical disorder is most frequently encountered in infants and children with severe diarrhea and vomiting, but it also occurs in adults. Schmidt,

Preliminary Study of the Penetration of Sodium Arsenite and Sodium Monochloroacetate Solutions into Trunks of Yellow Birch and Red Spruce

1. A study was made of the penetration of sodium arsenite and sodium monochloroacetate solutions through the exposed surface of the sapwood into the trunks of yellow birch (Betula lutea Michx. f.) and red spruce (Picea rubens Sarg.) trees. 2. The absorption of either chemical into spruce tended to decrease with time toward an equilibrium value which occurred in about 5 days. In addition, there was a diurnal fluctuation, with a slower rate occurring during the late-evening and early-morning hours. 3. Both chemicals showed an inverse relation between absorption into spruce and concentration. The tested concentrations of sodium arsenite penetrated more slowly than corresponding concentrations of sodium monochloroacetate. 4. Acid solutions of sodium monochloroacetate were taken up by red spruce faster than alkaline solutions. 5. A seasonal variation in absorption rate was observed for both chemicals in spruce. There was a sharp maximum in absorption on June 4, followed by a rapid decrease from mid-June through mid-July, followed by another peak in late July and early August. 6. No absorption of either solution was observed for yellow birch until after the cessation of bleeding, which occurred abruptly on May 26, when the leaves were half expanded. 7. The absorption of chemicals did not occur so readily in yellow birch as in red spruce. High concentrations of treating chemicals resulted in a net outward movement of water from the birch tree into the reservoirs.

Offshore Characteristics in the Deep Waters of the Strait of Georgia as Indicated by Bathypelagic Fish

An attempt is made from oceanographical observations to explain the occurrence of certain bathypelagic species of fish which have been captured in the bottom waters of the southern Strait of Georgia. It is noted that there is a considerable seaward surface Sow of water from the Fraser River. The water from intermediate depths over the continental shelf forms the inflowing deep water of Juan de Fuca Strait mixing with the Fraser River water in the turbulent channels of the San Juan Archipelago. This mixture forms the deep inflowing water of southern Strait of Georgia and the outflowing surface water of the Juan de Fuca Strait as shown by salinity distribution and current measurements. The net inward movement of deep water is suggested as an agent of transport or a directive factor for the occurrence of these fish in this region. Physical and chemical conditions of the deep water in the Strait of Georgia are shown to be only slightly different from those found in the intermediate offshore water. It is probable that a combination of factors provides conditions suitable for survival of these species in the deep water of the southern Strait of Georgia.

Rotational water movements in western Lake Erie

SummaryPrevious studies of the currents in western Lake Erie have been based on one method of investigation, drift bottles or drift cards. The studies revealed a gyral around Pelee Island. However, later evidence indicated that a much larger area was involved. The hypothesis of a net rotary movement of water in the western basin was confirmed. The force which is believed to produce the rotation is the primary longitudinal seiche which becomes a derived wave in the western basin. The island region acts as a spill-way for the overflowing seiche. The present study employed five different simple techniques to establish the pattern of water movements. 1. Lake level records at three strategic locations in western Lake Erie showed a rise and fall of water level, progressing in a clockwise direction around the basin.2. Wind generated surface currents move to the northeast under the prevailing southwest winds. This was shown by the movement of drift cards. The prevailing southwest winds contribute to the rotation of water in the western basin.3. Isotherms are distorted by the seiche action and the distortion showed a definite movement of water westward through the South Channels, and a northward movement through the island region. Net outflow occurred only through the Pelee Passage.4. Light transmission data, used as a measure of turbidity, showed the deflection of turbid water toward the north and an ingress of clear water from the east. Extremely turbid water was shown to enter the western basin from the Maumee River. The pattern of turbidity in western Lake Erie corresponds closely to the current pattern indicated by the distortion of isotherms.5. The net flow of water into and out of the western basin has been determined using direct current measurements. The net inflow through the South Channels was 57,600 cfs. The inflow plus the average river discharge into the western basin of 184,000 cfs was moved out of the western basin through the Pelee Passage. The net outflow through the Pelee Passage was 209,300 cfs.