OSMOTIC INHIBITION OF THE NATRIFERIC RESPONSE OF THE TOAD URINARY BLADDER TO VASOPRESSIN

1975 ◽  
Vol 67 (1) ◽  
pp. 119-125
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Water Movement ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Electrical Potential Difference ◽  
Osmotic Gradient

SUMMARY The electrical potential difference and short-circuit current (scc, reflecting active transmural sodium transport) across the toad urinary bladder in vitro was unaffected by the presence of hypo-osmotic solutions bathing the mucosal (urinary) surface, providing that the transmural flow of water was small. Vasopressin increased the scc across the toad bladder (the natriferic response), but this stimulation was considerably reduced in the presence of a hypo-osmotic solution on the mucosal side, conditions under which water transfer across the membrane was also increased. This inhibition of the natriferic response did not depend on the direction of the water movement, for if the osmotic gradient was the opposite way to that which normally occurs, the response to vasopressin was still reduced. The natriferic response to cyclic AMP was also inhibited in the presence of an osmotic gradient. Aldosterone increased the scc and Na+ transport across the toad bladder but this response was not changed when an osmotic gradient was present. The physiological implications of these observations and the possible mechanisms involved are discussed.

scholarly journals EFFECTS OF CYTOCHALASIN B ON THE RESPONSE OF TOAD URINARY BLADDER TO VASOPRESSIN

1974 ◽  
Vol 63 (3) ◽  
pp. 986-997 ◽  
Author(s):  
Walter L. Davis ◽  
David B. P. Goodman ◽  
Richard J. Schuster ◽  
Howard Rasmussen ◽  
James H. Martin
Keyword(s):  
Urinary Bladder ◽  
Water Permeability ◽  
Morphological Study ◽  
Cytochalasin B ◽  
Water Movement ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Osmotic Response

A combined physiological and morphological study of the effects of cytochalasin B (CB) on the toad urinary bladder has been carried out. CB inhibits the hydro-osmotic response to vasopressin without altering basal water permeability or diffusion, or the increase in 3H2O diffusion observed after hormone addition. Although CB increases [22Na]-, [36Cl]-, and [14C]urea fluxes, and decreases transepithelial potential, no alteration in basal short-circuit current, the vasopressin-induced increase in this parameter, or [14C]inulin permeability occurs. In the absence of hormone, CB does not markedly alter the structure of the toad bladder. However, in the presence of vasopressin, CB induces the formation of large intracellular vacuoles. These results suggest a possible coupling of solute and water movement across the tissue.

Ion transport and structure of urinary bladder epithelium of Amphiuma

1976 ◽  
Vol 231 (2) ◽  
pp. 501-508 ◽  
Author(s):  
TL Mullen ◽  
M Kashgarian ◽  
D Biemesderfer ◽  
GH Giebisch ◽  
TU Biber
Keyword(s):  
Urinary Bladder ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Cell Types ◽  
Surface Epithelium ◽  
Electrical Potential Difference ◽  
Basal Cells ◽  
Bladder Epithelium

The urinary bladder of Amphiuma exhibits stable transport properties and an electrical potential difference in vitro. The lumen is significantly negative to the serosa and under short-circuited conditions flux rations for Na and Cl of 5.92 +/- 0.42 and 1.81 +/- 0.20, respectively, were observed. The close agreement between the short-circuit current and net Na flux suggests that most, if not all, of the current is carried by Na. Both ouabain and amiloride decreased the short-circuit current and the mucosal-to-serosal (M leads to S) flux of Na. Furosemide caused a transient increase in the M leads to S flux of Na and Cl but ADH was without effect. In bladders that had high transmural resistance, a net movement of K in the M leads to S direction under short-circuited conditions with flux ratios of up to 2 could be observed. The epithelium of the Amphiuma bladder consists of three cell types: granular cells, basal cells, and mitochondria-rich cells. No goblet cells are present. The mitochondria-rich cells comprise less than 5% of the population of the surface epithelium in Amphiuma in contrast to other amphibian bladders, where it accounts for up to 25% of the population.

Effect of calcium on ion transport and electrical properties of tracheal epithelium

1978 ◽  
Vol 44 (6) ◽  
pp. 900-904 ◽  
Author(s):  
M. G. Marin ◽  
M. M. Zaremba
Keyword(s):  
Electrical Properties ◽  
Ion Transport ◽  
Calcium Concentration ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Tracheal Epithelium ◽  
Electrical Potential Difference ◽  
Tracheal Lumen

Active transport of Cl- toward the tracheal lumen and Na+ away from the lumen creates an electrical potential difference across dog tracheal epithelium. This study examined in vitro the effect of varying calcium concentration in the bathing media on the ion transport and electrical properties of dog tracheal epithelium. In six pairs of epithelia, changing calcium concentration from 1.9 to 0 mM resulted in a significant decrease in electrical resistance, from 318 +/- 36 to 214 +/- 24 omega.cm2. Short-circuit current and net Cl- and Na+ fluxes measured under short-circuit conditions were not changed significantly. Changing calcium concentration from 1.9 to 10 mM resulted in no significant change from control in the electrical properties nor in net Cl- and Na+ fluxes (short-circuit conditions). Histamine (10(-4) M) produced a significantly smaller increase in short-circuit current in 0 than in 1.9 mM Ca2+ (+5 +/- 2 vs. +12 +/- 2 microamperemeter/cm2). However, electrical changes were not significantly different in 1 or 10 mM Ca2+. These results indicate that calcium lack increased permeability of tracheal epithelium and that the increase in short-circuit current due to histamine depended in part on calcium.

Effect of acetazolamide on sodium and chloride transport by in vitro rabbit ileum

1975 ◽  
Vol 228 (6) ◽  
pp. 1808-1814 ◽  
Author(s):  
HN Nellans ◽  
RA Frizzell ◽  
SG Schultz
Keyword(s):  
Cyclic Amp ◽  
Chloride Transport ◽  
Short Circuit ◽  
Electrical Potential ◽  
Direct Interaction ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Membrane Component ◽  
Rabbit Ileum

Acetazolamide (8 mM) aboishes active Cl absorption and inhibits but does not abolish active Na absorption by stripped, short-circuited rabbit ileum. These effects are not accompanied by significant changes in the transmural electrical potential difference or short-circuit current. Studies of the undirectional influxes of Na andCl indicate that acetazolamide inhibits the neutral, coupled NaCl influx process at the mucosal membranes. This action appears to explain the observed effect of acetazolamide on active, transepithelial Na and Cl transport. Acetazolamide did not significantly inhibit either spontaneous or theophylline-induced Cl secretion by this preparation, suggesting that the theophylline-induced secretion may not simply be due tothe unmasking of a preexisting efflux process when the neutral influx mechanism is inhibited by theophylline. Finally, inhibition of the neutral NaCl influx process by acetazolamide does not appear to be attributable to an inhibition of endogenous HCO3production or an elevation in intracellular cyclic-AMP levels. Instead, it appearstheat the effect of acetazolamide is due to a direct interaction with a membrane component involved in the coupled influx process.

An Investigation of the Role of Possible Neural Mechanisms in Cholera Toxin-Induced Secretion in Rabbit Ileal Mucosa in Vitro

1989 ◽  
Vol 77 (2) ◽  
pp. 161-166 ◽  
Author(s):  
K. J. Moriarty ◽  
N. B. Higgs ◽  
M. Woodford ◽  
L. A. Turnberg
Keyword(s):  
Cholera Toxin ◽  
Fluid Transport ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Rabbit Ileum ◽  
Ileal Mucosa

1. Cholera toxin stimulates intestinal secretion in vitro by activation of mucosal adenylate cyclase. However, it has been proposed that cholera toxin promotes secretion in vivo mainly through an indirect mechanism involving enteric neural reflexes. 2. We examined this hypothesis further by studying the influence of neuronal blockade on cholera toxin-induced changes in fluid transport across rabbit ileum in vitro. Mucosa, stripped of muscle layers, was mounted in flux chambers and luminal application of crude cholera toxin (2 μg/ml) caused a delayed but sustained rise in the short-circuit current, electrical potential difference and Cl− secretion. Pretreatment with the nerve-blocking drug, tetrodotoxin (5 × 10−6 mol/l serosal side), failed to influence the secretory response to cholera toxin, and addition of tetrodotoxin at the peak response to cholera toxin also had no effect. 3. That tetrodotoxin could block neurally mediated secretagogues was confirmed by the demonstration that the electrical responses to neurotensin (10−7 mol/l and 10−8 mol/l) were blocked by tetrodotoxin (5 × 10−6 mol/l). Furthermore, the response to cholera toxin of segments of ileum, which included the myenteric, submucosal and mucosal nerve plexuses, was not inhibited by tetrodotoxin. 4. We conclude that cholera toxin-induced secretion in rabbit ileum in vitro is not mediated via a neurological mechanism.

In vitro studies of sodium transport across the lower intestine of a desert parrot

1980 ◽  
Vol 239 (3) ◽  
pp. R285-R290
Author(s):  
E. Skadhauge ◽  
T. J. Dawson
Keyword(s):  
Short Circuit ◽  
Electrical Potential ◽  
Flux Ratio ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Na Transport ◽  
Salt Loading ◽  
Ussing Chambers ◽  
Lower Intestine

The lower intestine (coprodeum and colon) of the Australian parrot, the galah, was mounted in Ussing chambers. Short-circuit current (SCC), electrical potential difference (PD), and unidirectional fluxes of Na and Cl were measured in birds that were fed mixed seeds or were NaCl loaded. The net Na transport of both coprodeum and colon was nearly equal to the SCC, and the flux ratio for Cl was unity. In birds which received mixed seeds, average coprodeal Na transport was 7.8 mu eq . cm-2 . h-1, and PD was 19 mV. The Km for Na was 5.7 meq/l. In colon, Na transport was reduced by 67% and PD by 70%. The ratio between unidirectional Na and Cl fluxes in the serosa-mucosa direction was 0.7. Salt loading suppressed coprodeal, but increased colonic Na transport. The coprodeal and colonic SCC and NA transport of birds receiving mixed seeds were inhibited by amiloride on the mucosal side. Colonic SCC of NaCl-loaded birds was only slightly reduced by amiloride (by 17%), but stimulated by amino acids (by 18%).

Sodium and chloride transport in the isolated intestine of the earthworm, Lumbricus terrestris (L.)

1982 ◽  
Vol 97 (1) ◽  
pp. 197-216
Author(s):  
J. C. Cornell
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Electrical Potential ◽  
Lumbricus Terrestris ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Ionic Basis ◽  
Good Agreement

1. Measurements of electrical potential difference (PD), short-circuit current (SCC) and unidirectional fluxes of sodium and chloride were made across portions of the intestine. Based on the results, the intestine can be divided into at least four physiologically distinct regions. 2. These four physiological regions, designated from anterior to posterior as R I-II, R III A, R III B and R IV, do not completely correspond to the four anatomically distinct regions of the intestine. 3. The PD (serosal side positive) in R I-II, R III A, R III B and R IV is 1.08, 12.4, 5.61 and 31.7 mV, respectively. 4. The SCC in these same regions is 9.9, 50.4, 49.7, and 16.4 micro A cm2, respectively. 5. When short-circuited, net sodium and net chloride fluxes in the above regions are −0.36 and −0.27, 1.46*** and −0.92*, 1.74*** and −0.06 and 1.01*** and 0.07 mumol cm-2 h-1, respectively. Positive fluxes indicate net mucosal to serosal movements and asterisks indicate significant net fluxes (* P less than 0.05, *** P less than 0.001). 6. There is good agreement between the SCC and net sodium transport in R III B. In the other regions of the intestine the ionic basis of the SCC has not been completely explained. 7. The properties of the intestine in vitro appear to make the intestine well suited for the task of conserving sodium, a function which the intestine performs in vivo.

Aldosterone-induced, amiloride-inhibitable short-circuit current in the avian ileum

1987 ◽  
Vol 253 (2) ◽  
pp. G211-G216
Author(s):  
B. R. Grubb ◽  
P. J. Bentley
Keyword(s):  
Time Course ◽  
Short Circuit ◽  
Electrical Potential ◽  
Intestinal Transport ◽  
Short Circuit Current ◽  
Na Channel ◽  
Electrical Potential Difference ◽  
Adaptation Mechanisms ◽  
Channel Blocking

Transmural electrical potential difference, short-circuit current (Isc), and resistance were measured in vitro in the intestines of chickens. In birds maintained on a low-Na diet, there was a rise in Isc in the ileum and the colon but not in the duodenum or jejunum. A substantial portion of this Isc could be inhibited by the Na channel-blocking drug, amiloride. The low-Na diet results in elevated plasma levels of aldosterone and the effects of the diet on intestinal transport could be mimicked by administration of this hormone. The time course of the effects of these two treatments on the ileum and colon were quite different, as a much longer exposure was needed to elicit maximal effects in the ileum than in the colon, possibly due to the presence of two types of adaptation mechanisms. The responses observed may reflect an adaptation of mechanisms for increasing Na transport from the intestine. The presence of such a mechanism in the vertebrate ileum has until recently been in doubt.

Effect of imidazoles on active transport by gastric mucosa and urinary bladder

1965 ◽  
Vol 208 (6) ◽  
pp. 1183-1190 ◽  
Author(s):  
Darwin Alonso ◽  
Richard Rynes ◽  
John B. Harris
Keyword(s):  
Gastric Mucosa ◽  
Urinary Bladder ◽  
Competitive Inhibition ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Buffering Capacity ◽  
Toad Urinary Bladder ◽  
Inhibitory Effects ◽  
Active Sodium

Studies were undertaken to determine whether the stimulatory effect of histamine and the methyl xanthines on the frog gastric mucosa in vitro could be ascribed to the imidazole component of these compounds. The actively transported ions of gastric secretion appear in the form of hydrochloric acid and of a nonacid chloride component that is responsible for the short-circuit current (Isc). At 10–2 m, imidazole reduced acid secretion (Jh) by 80%, which was somewhat greater than the reduction produced by thiocyanate. N-methylimidazole, 2-methylimidazole, 4(5)-methylimidazole, and benzimidazole abolished Jh. The Isc tended to rise as Jh fell. In stimulated mucosae, imidazole and N-methylimidazole promptly reduced oxygen consumption (qO2) by 25%; thiocyanate had a delayed and lesser effect. Pyrazole, 4-hydroxymethylimidazole, and tris had little or no effect on Jh, Isc, or qO2. Imidazole and N-methylimidazole reduced active sodium transport by the toad urinary bladder by 50%. The results indicate that the inhibitory effects of the imidazoles cannot be ascribed to their buffering capacity or to competitive inhibition of histamine. Instead the effects may result from depletion of tissue content of adenosine-3',5'-phosphate or from interference with protein-bound phosphohistidine in oxidative phosphorylation.

Effect of acetylcholine on Cl- and Na+ fluxes across dog tracheal epithelium in vitro

1976 ◽  
Vol 231 (5) ◽  
pp. 1546-1549 ◽  
Author(s):  
MG Marin ◽  
B Davis ◽  
JA Nadel
Keyword(s):  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Atropine Sulfate ◽  
Open Circuit ◽  
Ion Flux ◽  
Potential Difference ◽  
Tracheal Epithelium ◽  
Electrical Potential Difference

Electrical potential difference is generated across canine tracheal epithelium by active transport of Cl- toward and Na+ away from the lumen. The present study examines the effects of acetylcholine on short-circuit current, potential difference, resistance, and fluxes of 36Cl and 24Na measured across pieces of canine tracheal epithelium mounted in Ussing-type chambers. Under short-circuit conditions, acetylcholine (5 X 10(-5) M) increased significantly net ion flux toward the lumen of Cl- (n equals 7) from +1.7 +/- SE 0.5 TO +3.3 +/- SE 0.5 mueq/cm2 - h, and of Na+ (n equals 7) from -0.8 +/- SE 0.2 to +0.5 +/- SE 0.2 mueq/cm2 - h. Under open-circuit conditions, acetylcholine (5 X 10(-5) M) increased significantly the unidirectional flux of Cl- (n equals 6) toward the lumen from 4.7 +/- SE 1.3 to 5.9 +/- SE 1.4 mueq/cm2 - h, while the other measured fluxes did not change significantly, suggesting that net Cl- flux had increased toward the lumen. Atropine sulfate (10(-8) M) prevented the response to acetylcholine (5 X 10(-5) M). The increased ion flux due to acetylcholine may mediate water secretion into the airway lumen, and this secretion may have important effects on the physical properties of the liquid through which the respiratory cilia beat.

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