scholarly journals PATHS OF TRANSTUBULAR WATER FLOW IN ISOLATED RENAL COLLECTING TUBULES

1969 ◽  
Vol 41 (2) ◽  
pp. 562-576 ◽  
Author(s):  
Jared J. Grantham ◽  
Charles E. Ganote ◽  
Maurice B. Burg ◽  
Jack Orloff
Keyword(s):  
Water Flow ◽  
Direct Evidence ◽  
Extracellular Fluid ◽  
Isotonic Solution ◽  
Intercellular Spaces ◽  
Osmotic Swelling ◽  
Induced Flow ◽  
Collecting Tubules ◽  
Intercellular Channel ◽  
Hydrostatic Pressure Difference

The cells of perfused rabbit collecting tubules swell and the intercellular spaces widen during osmotic flow of water from lumen to bath induced by antidiuretic hormone (ADH). Ouabain had no influence on these changes. In the absence of net water flow intercellular width was unaffected when tubules were swollen in hypotonic external media. Therefore, during ADH-induced flow widening of intercellular spaces is not a consequence of osmotic swelling of a closed intercellular compartment containing trapped solutes, but rather is due to flow of solution through the channel. Direct evidence of intercellular flow was obtained. Nonperfused tubules swollen in hypotonic media were reimmersed in isotonic solution with resultant entry of water into intercellular spaces. The widened spaces gradually collapsed completely. Spaces enlarged in this manner could be emptied more rapidly by increasing the transtubular hydrostatic pressure difference. In electron micrographs a path of exit of sufficient width to accommodate the observed rate of fluid flow was seen at the base of the intercellular channel. It is concluded that the intercellular spaces communicate with the external extracellular fluid and that water, having entered the cells across the luminal plasma membrane in response in ADH, leaves the cells by osmosis across both the lateral and basilar surface membranes.

scholarly journals ULTRASTRUCTURAL STUDIES OF VASOPRESSIN EFFECT ON ISOLATED PERFUSED RENAL COLLECTING TUBULES OF THE RABBIT

1968 ◽  
Vol 36 (2) ◽  
pp. 355-367 ◽  
Author(s):  
Charles E. Ganote ◽  
Jared J. Grantham ◽  
Harold L. Moses ◽  
Maurice B. Burg ◽  
Jack Orloff
Keyword(s):  
Water Transport ◽  
Water Flow ◽  
Cell Membranes ◽  
Bulk Water ◽  
Ultrastructural Changes ◽  
Rabbit Kidney ◽  
Intercellular Spaces ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Collecting Tubules

Isolated cortical collecting tubules from rabbit kidney were studied during perfusion with solutions made either isotonic or hypotonic to the external bathing medium. Examination of living tubules revealed a reversible increase in thickness of the cellular layer, prominence of lateral cell membranes, and formation of intracellular vacuoles during periods of vasopressin-induced osmotic water transport. Examination in the electron microscope revealed that vasopressin induced no changes in cell structure in collecting tubules in the absence of an osmotic difference and significant bulk water flow across the tubule wall. In contrast, tubules fixed during vasopressin-induced periods of high osmotic water transport showed prominent dilatation of lateral intercellular spaces, bulging of apical cell membranes into the tubular lumen, and formation of intracellular vacuoles. It is concluded that the ultrastructural changes are secondary to transepithelial bulk water flow and not to a direct effect of vasopressin on the cells, and that vasopressin induces osmotic flow by increasing water permeability of the luminal cell membrane. The lateral intercellular spaces may be part of the pathway for osmotically induced transepithelial bulk water flow.

Effect of ADH on Rat Renal Papilla, an Ultrastructural and Cytochemical Study

1973 ◽  
Vol 31 ◽  
pp. 410-411
Author(s):  
C. N. Sun ◽  
H. J. White ◽  
E. J. Towbin
Keyword(s):  
Electron Microscopy ◽  
Diabetes Insipidus ◽  
Renal Papilla ◽  
Milk Diet ◽  
Intercellular Spaces ◽  
Cytochemical Study ◽  
Collecting Tubule ◽  
Concentrate Urine ◽  
Staining Techniques ◽  
Collecting Tubules

Diabetes insipidus and compulsive water drinking are representative of two categories of antidiuretic hormone (ADH) lack. We studied a strain of rats with congenital diabetes insipidus homozygote (DI) and normal rats on an isocaloric fortified dilute milk diet. In both cases, the collecting tubules could not concentrate urine. Special staining techniques, Alcian Blue-PAS for light microscopy and lanthanum nitrate for electron microscopy were used to demonstrate the changes in interstitial mucopolysaccharides (MPS). The lanthanum staining was done according to the method of Khan and Overton.Electron microscopy shows cytoplasmic lesions, vacules, swelling and degenerating mitochondria and intercellular spaces (IS) in the collecting tubule cells in DI and rats on milk diet.

scholarly journals Loss of potassium from embryonic chick hearts in potassium-free media with and without calcium

1938 ◽  
Vol 124 (837) ◽  
pp. 446-450
Keyword(s):  
Phosphate Buffer ◽  
Direct Evidence ◽  
Watch Glass ◽  
Chick Embryos ◽  
Embryonic Chick ◽  
Intercellular Spaces ◽  
Experimental Solution ◽  
Free Media ◽  
And Control ◽  
Day By Day

Experiments already described (Murray 1938) led to the inference that the cells of the chick embryonic heart lose potassium in potassium-free media. The experiments here described provide direct evidence of this. The hearts were dissected out of 2 ½-3 day chick embryos and placed in the solution PC (Table I) until they had started to beat. They were then thoroughly washed, and were allowed to lie for 5 min. (2 min. in Exp. 1) in the last wash. This last wash is called control A. The solutions used for washing were from the same flasks as the experimental solution. After their passage through control A the hearts were transferred to 2 c.c. of the experimental solution in a Jena watch-glass. After various times in this the hearts were discarded and both the experimental solution and control A were collected. If the experiment extended over more than 1 day the experimental solution and control A were used over again day by day until all the hearts in the experiment had passed through them. The use of control A was necessary for two reasons: ( a ) to show that potassium was not still being washed out of the intercellular spaces at the end of washing ( b ) in experiments lasting over several days the washing solution was fresh each day, but the experimental solution was of course not changed. Hence any small amount of potassium being carried over from the last wash would accumulate in the experimental solution because of the daily increment and might seriously affect the result; but by leaving the hearts for several minutes in the last wash (control A) and by not changing it for fresh on successive days, any such increase would be detected in that solution. In addition to control A, a daily sample (control B) was taken from the same flasks as the solutions used for washing. Details of the solutions are given in Table I ; a phosphate buffer was always used.

scholarly journals Volume regulation by flounder red blood cells in anisotonic media

1977 ◽  
Vol 69 (5) ◽  
pp. 537-552 ◽  
Author(s):  
PM Cala
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Water Flow ◽  
Blood Cells ◽  
Volume Regulation ◽  
Control Cell ◽  
Regulatory Volume Decrease ◽  
Electrochemical Gradient ◽  
Osmotic Swelling ◽  
Inorganic Cation

The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.

scholarly journals THE EFFECT OF SMOOTH MUSCLE ON THE INTERCELLULAR SPACES IN TOAD URINARY BLADDER

1970 ◽  
Vol 46 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Donald R. DiBona ◽  
Mortimer M. Civan
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Water Flow ◽  
Toad Urinary Bladder ◽  
Reliable Index ◽  
Intercellular Spaces ◽  
Phase Microscopy ◽  
Osmotic Water ◽  
Smooth Muscle Relaxant ◽  
Osmotic Water Flow

Phase microscopy of toad urinary bladder has demonstrated that vasopressin can cause an enlargement of the epithelial intercellular spaces under conditions of no net transfer of water or sodium. The suggestion that this phenomenon is linked to the hormone's action as a smooth muscle relaxant has been tested and verified with the use of other agents effecting smooth muscle: atropine and adenine compounds (relaxants), K+ and acetylcholine (contractants). Furthermore, it was possible to reduce the size and number of intercellular spaces, relative to a control, while increasing the rate of osmotic water flow. A method for quantifying these results has been developed and shows that they are, indeed, significant. It is concluded, therefore, that the configuration of intercellular spaces is not a reliable index of water flow across this epithelium and that such a morphologic-physiologic relationship is tenuous in any epithelium supported by a submucosa rich in smooth muscle.

Reconstitution of calyculin-inhibited K-Cl cotransport in dog erythrocyte ghosts by exogenous PP-1

1996 ◽  
Vol 270 (3) ◽  
pp. C898-C902 ◽  
Author(s):  
T. Krarup ◽  
P. B. Dunham
Keyword(s):  
Protein Phosphatase ◽  
Direct Evidence ◽  
Potent Inhibitor ◽  
Protein Phosphatases ◽  
Calyculin A ◽  
Osmotic Swelling ◽  
Maximal Activation ◽  
Resealed Ghosts ◽  
K Transport

Osmotic swelling of dog and other mammalian erythrocytes activates Cl-dependent K transport, K-Cl cotransport. This activation can be abolished by nanomolar concentrations of calyculin, a potent inhibitor of serine-threonine protein phosphatases. Therefore, K-Cl cotransport is probably activated by dephosphorylation by a type 1 and/or type 2A protein phosphatase (PP-1 and PP-2A, respectively). This was tested directly by incorporating exogenous protein phosphatases into resealed ghosts made from dog erythrocytes previously exposed to calyculin. K-Cl cotransport was nearly completely inhibited in the ghosts. Incorporation of PP-1 reconstituted K-Cl cotransport. Maximal reconstitution was up to 90% of the control flux in the ghosts and 0.1 U PP-1/ml lysate gave half-maximal reconstitution of cotransport. In contrast, PP-2A had no effect. This result with PP-1 provides direct evidence that K-Cl cotransport is activated by PP-1 in dog erythrocytes. Half-maximal activation of K-Cl cotransport required approximately 180 molecules of PP-1 per ghost.

Transport of Exogenous D-glucose by the Integument of a Polychaete Worm (Nereis Diversicolor Müller)

1975 ◽  
Vol 62 (2) ◽  
pp. 243-265
Author(s):  
GREGORY A. AHEARN ◽  
JØRGEN GOMME
Keyword(s):  
Sea Water ◽  
Extracellular Fluid ◽  
Epidermal Cells ◽  
Transport Systems ◽  
Intercellular Spaces ◽  
Lateral Border ◽  
Nereis Diversicolor ◽  
Outer Membranes ◽  
Maximum Value ◽  
Order Of Magnitude

1. Integumentary exchange of radio-labelled D-glucose in the brackish-water polychaete worm Nereis diversicolor (Annelida; Polychaeta) was investigated. 2. In animals acclimated to 50% sea water, the influx of D-glucose was measured, and shown to occur largely across the outward-facing membranes of the epidermal cells. 3. Transfer of exogenous D-glucose across the outer membranes occurs by facilitated transfer, involving two different transport systems. One of these has a Kt (transport constant) of ⋍ 5 μM, i.e. of the order of magnitude of environmental D-glucose concentrations. The Kt for the other system is at least ten times higher. 4. The D-glucose is rapidly metabolized by the epidermal cells. Small amounts of unmetabolized D-glucose are released to the extracellular fluid, and probably to the medium. 5. The maximal D-glucose outflux through the apical border of the epidermal cells is at least 4 times smaller than the outflux through the baso-lateral border. 6. A maximum value is given for the diffusion permeability of D-glucose through the intercellular spaces of the integument. Applying this figure, the loss by intercellular diffusion was found not to exceed the D-glucose influx into the epidermal cells.

Clinical use of diuretics

2015 ◽  
Author(s):  
David H. Ellison ◽  
Arohan R. Subramanya
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Extracellular Fluid ◽  
Chronic Administration ◽  
Distal Convoluted Tubule ◽  
Loop Diuretics ◽  
Sodium Reabsorption ◽  
Thick Ascending Limb ◽  
Response Curves ◽  
Collecting Tubules

Diuretics are widely employed to treat extracellular fluid volume expansion caused by heart failure, cirrhosis of the liver, nephrotic syndrome, and chronic kidney disease. Major classes of diuretic inhibit sodium reabsorption along the proximal tubule, the loop of Henle, the distal convoluted tubule, and the connecting and collecting tubules. Loop diuretics have the highest ceiling of action and often form the cornerstones of diuretic treatment of oedema. Members of this class are short-acting drugs, with different bioavailabilities, the specifics of which contribute importantly to a rational and effective approach to their use. They are not filtered substantially because they are all protein bound. They enter tubules by secretion along the proximal tubule, thereby gaining access to the Na-K-2Cl cotransporter of the thick ascending limb. Their dose–response curves are sigmoidal and altered by several disease processes. Chronic administration can elicit adaptive processes along the nephron that limit their efficacy. Distal convoluted tubule diuretics, such as the thiazides, inhibit NaCl absorption along the distal convoluted tubule. While used predominantly to treat hypertension, they are also useful to treat oedema, especially when combined with loop diuretics. Drugs acting along the connecting tubule and collecting duct either inhibit Na+ channels directly or block mineralocorticoid receptors. These drugs are effective in states of very high aldosterone secretion, and can also be used to reduce the hypokalaemia caused by other classes of diuretics. An evidence-based approach to treating the oedematous patient is described.

scholarly journals MDCK cells are capable of water secretion and reabsorption in response to changes in the ionic environment

2017 ◽  
Vol 95 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Janne P. Capra ◽  
Sinikka M. Eskelinen
Keyword(s):  
Water Flow ◽  
Chloride Channels ◽  
Mdck Cells ◽  
Extracellular Fluid ◽  
Chloride Ion ◽  
Chloride Secretion ◽  
Chloride Ions ◽  
Intestinal Epithelia ◽  
Fluorescent Markers ◽  
Water Secretion

A prerequisite for tissue electrolyte homeostasis is highly regulated ion and water transport through kidney or intestinal epithelia. In the present work, we monitored changes in the cell and luminal volumes of type II Madin-Darby canine kidney (MDCK) cells grown in a 3D environment in response to drugs, or to changes in the composition of the basal extracellular fluid. Using fluorescent markers and high-resolution spinning disc confocal microscopy, we could show that lack of sodium and potassium ions in the basal fluid (tetramethylammonium chloride (TMACl) buffer) induces a rapid increase in the cell and luminal volumes. This transepithelial water flow could be regulated by inhibitors and agonists of chloride channels. Hence, the driving force for the transepithelial water flow is chloride secretion, stimulated by hyperpolarization. Chloride ion depletion of the basal fluid (using sodium gluconate buffer) induces a strong reduction in the lumen size, indicating reabsorption of water from the lumen to the basal side. Lumen size also decreased following depolarization of the cell interior by rendering the membrane permeable to potassium. Hence, MDCK cells are capable of both absorption and secretion of chloride ions and water; negative potential within the lumen supports secretion, while depolarizing conditions promote reabsorption.

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