scholarly journals Salinity Acclimation and Intestinal Salt Transport in the Flounder: the Role of the Basolateral Cell Membrane

1987 ◽  
Vol 128 (1) ◽  
pp. 371-382 ◽  
Author(s):  
J. S. GIBSON ◽  
J. C. ELLORY ◽  
B. LAHLOU
Keyword(s):  
Cell Membrane ◽  
Apical Cell ◽  
Salt Transport ◽  
Cell Membrane Permeability ◽  
Salt Adaptation ◽  
Salinity Acclimation ◽  
Apical Cell Membrane ◽  
Selective Permeability ◽  
Basolateral Cell Membrane ◽  
The Difference

1. Intestinal absorption of Na+ and Cl−, measured using bidirectional tracer fluxes, is higher in saltwater (SW)-acclimated flounders than in freshwater (FW)- acclimated ones. 2. Removal of the selective permeability of the apical cell membrane by application of amphotericin B to the mucosal solution enhances the difference in Na+ transport, whilst the difference in Cl− absorption is lost. 3. Transepithelial resistance and JsmNa were similar between the two groups of fish, whilst JsmCl, was always greatest in SW-acclimated tissues, even after mucosal application of amphotericin. 4. Analysis of the present results and previous work suggests that the principal acclimatory changes following salt adaptation occur in the basolateral cell membrane, and that both the Na+, K+-ATPase activity and the basolateral cell membrane permeability to Cl− are increased in the SW-acclimated tissues.

The collecting tubule of Amphiuma. I. Electrophysiological characterization

1987 ◽  
Vol 253 (6) ◽  
pp. F1263-F1272 ◽  
Author(s):  
M. Hunter ◽  
J. D. Horisberger ◽  
B. Stanton ◽  
G. Giebisch
Keyword(s):  
Cell Membrane ◽  
Cell Model ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Potassium Conductance ◽  
Sodium Reabsorption ◽  
Apical Cell Membrane ◽  
Cation Selectivity ◽  
Basolateral Cell Membrane ◽  
Collecting Tubules

Single collecting tubules of Amphiuma kidneys were perfused in vitro to characterize their electrophysiological properties. The lumen-negative potential (-24 mV) was abolished by amiloride in the lumen and by ouabain in the bath. Ion substitution experiments in the lumen demonstrated the presence of a large sodium conductance in the apical cell membrane, but no evidence was obtained for a significant potassium or chloride conductance. Ion substitutions in the bath solution and the depolarizing effect of barium on the basolateral membrane potential demonstrated the presence of a large potassium conductance in the basolateral cell membrane. Measurements of dilution potentials in amiloride-treated tubules revealed a modest cation selectivity of the paracellular pathway. These results support a cell model in which sodium reabsorption occurs by electrodiffusion across the apical cell membrane and active transport across the basolateral cell membrane. The absence of a detectable potassium conductance in the apical cell membrane suggests that secretion of this ion cannot take place by diffusion from cell to lumen.

Conductive properties of the rabbit outer medullary collecting duct: inner stripe

1985 ◽  
Vol 248 (4) ◽  
pp. F500-F506 ◽  
Author(s):  
B. M. Koeppen
Keyword(s):  
Cell Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Rabbit Kidney ◽  
Apical Cell Membrane ◽  
Basolateral Cell Membrane ◽  
Medullary Collecting Duct ◽  
Conductive Properties

Segments of outer medullary collecting duct were dissected from the inner stripe of the rabbit kidney (OMCDi) and perfused in vitro. The conductive properties of the tubule epithelium and individual cell membranes were determined by means of cable analysis and intracellular voltage-recording microelectrodes. In 35 tubules the transepithelial voltage (VT) and resistance (RT) averaged 17.2 +/- 1.4 mV, lumen positive, and 58.6 +/- 5.3 k omega X cm, respectively. The basolateral membrane voltage, (Vbl) was -29.2 +/- 2.1 mV (n = 23). The apical cell membrane did not contain appreciable ion conductances, as evidenced by the high values of apical cell membrane fractional resistance (fRa = Ra/Ra + Rb), which approached unity (0.99 +/- 0.01; n = 23). Moreover, addition of amiloride or BaCl2 to the tubule lumen was without effect on the electrical characteristics of the cell, as was a twofold reduction in luminal [Cl-]. The conductive properties of the basolateral cell membrane were assessed with bath ion substitutions. A twofold reduction in bath [Cl-] depolarized Vbl by 14.7 +/- 0.4 mV (theoretical, 17 mV), while a 10-fold increase in bath [K+] resulted in only a 0.9 +/- 0.4 mV depolarization (theoretical, 61 mV). Substituting bath Na+ with tetramethylammonium (from 150 to 75 mM) was without effect. Reducing bath [HCO-3] from 25 to 5 mM (constant PCO2) resulted in a steady-state depolarization of Vbl of 8.4 +/- 0.4 mV that could not be attributed to conductive HCO-3 movement. Thus, the basolateral cell membrane is predominantly Cl- selective.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of trichlormethiazide or amiloride with PTH in stimulating Ca2+ absorption in rabbit CNT

1991 ◽  
Vol 261 (1) ◽  
pp. F36-F43 ◽  
Author(s):  
T. Shimizu ◽  
M. Nakamura ◽  
K. Yoshitomi ◽  
M. Imai
Keyword(s):  
Parathyroid Hormone ◽  
Cell Membrane ◽  
Apical Cell ◽  
Detectable Effect ◽  
Apical Cell Membrane ◽  
Positive Direction ◽  
Basolateral Cell Membrane ◽  
Collecting Ducts ◽  
Transepithelial Voltage ◽  
Renal Tubular

To determine the renal tubular site and mechanism of the anticalciuric effects of trichloromethiazide (TCM) and amiloride, we studied the effects of these diuretics on net Ca2+ absorption (JCa) in isolated rabbit connecting tubules (CNT) and cortical collecting ducts (CCD). TCM (100 microM) in the lumen increased JCa in the CNT without affecting lumen-negative transepithelial voltage (VT). This effect was dependent on the amount of parathyroid hormone (PTH, 0.1 or 1 nM) in the bath. TCM had no detectable effect on JCa in the absence of PTH. Addition of 100 microM ouabain to the bath decreased PTH-stimulated JCa and abolished the TCM-stimulated JCa. Elimination of Na+ from the lumen increased PTH-stimulated JCa. Under this condition the ability of TCM to increase JCa was abolished, suggesting that the inhibition of Na+ entry from the lumen with TCM may account for the increase in PTH-stimulated JCa. Elimination of Na+ from the bath in the presence of PTH decreased JCa and abolished the stimulatory effect of TCM on JCa in the presence of PTH. Changes in VT caused by amiloride may not account for the increase in JCa, because JCa was not changed when VT was deflected to more positive direction by increasing bath K+ from 5 to 15 mM. Neither TCM nor amiloride affected JCa in the CCD. From these observations, we speculate that the inhibition of Na+ entry across the apical cell membrane by either thiazides or amiloride may stimulate PTH-induced JCa. The intact Na(+)-Ca2+ antiporter in the basolateral cell membrane is essential for the anticalciuric effect of thiazides and amiloride.

scholarly journals Relationship between cell volume and ion transport in the early distal tubule of the Amphiuma kidney.

1985 ◽  
Vol 86 (1) ◽  
pp. 31-58 ◽  
Author(s):  
W B Guggino ◽  
H Oberleithner ◽  
G Giebisch
Keyword(s):  
Cell Membrane ◽  
Cell Volume ◽  
Cell Membranes ◽  
Apical Cell ◽  
Distal Tubule ◽  
Cell Swelling ◽  
Osmotic Swelling ◽  
Apical Cell Membrane ◽  
Basolateral Cell Membrane ◽  
Tubule Cells

The roles of apical and basolateral transport mechanisms in the regulation of cell volume and the hydraulic water permeabilities (Lp) of the individual cell membranes of the Amphiuma early distal tubule (diluting segment) were evaluated using video and optical techniques as well as conventional and Cl-sensitive microelectrodes. The Lp of the apical cell membrane calculated per square centimeter of tubule is less than 3% that of the basolateral cell membrane. Calculated per square centimeter of membrane, the Lp of the apical cell membrane is less than 40% that of the basolateral cell membrane. Thus, two factors are responsible for the asymmetry in the Lp of the early distal tubule: an intrinsic difference in the Lp per square centimeter of membrane area, and a difference in the surface areas of the apical and basolateral cell membranes. Early distal tubule cells do not regulate volume after a reduction in bath osmolality. This cell swelling occurs without a change in the intracellular Cl content or the basolateral cell membrane potential. In contrast, reducing the osmolality of the basolateral solution in the presence of luminal furosemide diminishes the magnitude of the increase in cell volume to a value below that predicted from the change in osmolality. This osmotic swelling is associated with a reduction in the intracellular Cl content. Hence, early distal tubule cells can lose solute in response to osmotic swelling, but only after the apical Na/K/Cl transporter is blocked. Inhibition of basolateral Na/K ATPase with ouabain results in severe cell swelling. This swelling in response to ouabain can be inhibited by the prior application of furosemide, which suggests that the swelling is due to the continued entry of solutes, primarily through the apical cotransport pathway.

Microelectrode studies of Necturus antral mucosa: electrical potentials and resistances

1983 ◽  
Vol 244 (1) ◽  
pp. G71-G75
Author(s):  
T. P. Grady ◽  
L. Y. Cheung
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Apical Cell ◽  
Cell Membrane Potential ◽  
Transepithelial Resistance ◽  
Bathing Solution ◽  
Antral Mucosa ◽  
Apical Cell Membrane ◽  
Electrical Potentials ◽  
Basolateral Cell Membrane

Intracellular microelectrode techniques were applied to Necturus antral mucosa. Stable intracellular impalements were obtained with 15-50 M omega microelectrodes filled with 3M KCl. It was possible to change rapidly the mucosal bathing solution while maintaining the microelectrode in the cell. With these techniques, we were able to measure the electrical potentials and resistances of the cell membranes and the shunt pathway. The transepithelial potential was -4.9 +/- 1.3 mV, serosal solution reference. Apical cell membrane potential was -43.9 +/- 0.6 mV, cell negative to the mucosal solution. Basolateral cell membrane potential was -48.8 +/- 1.3 mV, cell negative to serosal solution. Transepithelial resistance was 427 +/- 66 omega . cm2. The ratio of apical to basolateral membrane resistances was 3.4 +/- 0.3. The electrical resistances of the transcellular and paracellular pathway were determined by the measurement of the total transepithelial resistance and the ratio of apical to basolateral cell membrane resistances before and after blocking apical membrane sodium permeability with amiloride. The resistances of the apical cell membrane, basolateral cell membrane, and the shunt were 2,203 +/- 585, 1,296 +/- 384, and 604 +/- 81 omega . cm2, respectively (mean +/- SE). Calculations from these measurements indicate that the shunt contribution to transepithelial conductance was approximately 85%.

Conductive properties of the rabbit outer medullary collecting duct: outer stripe

1986 ◽  
Vol 250 (1) ◽  
pp. F70-F76 ◽  
Author(s):  
B. M. Koeppen
Keyword(s):  
Cell Membrane ◽  
Collecting Duct ◽  
Apical Cell ◽  
Rabbit Kidney ◽  
Cell Type ◽  
Apical Cell Membrane ◽  
Basolateral Cell Membrane ◽  
Outer Stripe ◽  
Medullary Collecting Duct ◽  
Conductive Properties

Segments of the outer medullary collecting duct were dissected from the outer stripe of the rabbit kidney (OMCDo) and perfused in vitro. The conductive properties of the tubule epithelium and individual cell membranes were determined by means of cable analysis and intracellular voltage-recording microelectrodes. The transepithelial voltage (VT) and resistance (RT) averaged -10.7 +/- 2.5 mV, lumen negative, and 28.5 +/- 2.9 k omega X cm (n = 27), respectively. Two cell types could be defined by their electrophysiological properties. One cell type (n = 7) had a mean basolateral membrane voltage (Vbl) of -30.1 +/- 2.4 mV, a fractional resistance of the apical membrane (fRa = Ra/Ra + Rbl) near unity (0.99 +/- 0.01), and a predominantly Cl(-)-selective basolateral cell membrane. The second cell type (n = 27) had a mean Vbl of -63.7 +/- 2.7 mV, a fRa of 0.81 +/- 0.02, and a predominantly K+-selective basolateral cell membrane. The present study focused on defining the conductive properties of this latter cell type. Amiloride (10(-5) M) and BaCl2 (2 mM) were used as probes of apical cell membrane Na+ and K+ conductive pathways, respectively. Amiloride increased fRa from 0.80 +/- 0.02 to 0.98 +/- 0.01 (n = 12), whereas BaCl2 increased fRa from 0.77 +/- 0.03 to 0.82 +/- 0.03 (n = 9). The conductive properties of the basolateral cell membrane were assessed by ion substitutions of the bath solution. A 10-fold increase in the bath [K+] depolarized Vbl by 34.9 +/- 1.9 mV (n = 16) in less than 1 s, indicating that this membrane was predominantly K+ selective.(ABSTRACT TRUNCATED AT 250 WORDS)

Ionic conductive properties and electrophysiology of the rabbit cortical collecting tubule

1982 ◽  
Vol 243 (1) ◽  
pp. F81-F95 ◽  
Author(s):  
R. G. O'Neil ◽  
E. L. Boulpaep
Keyword(s):  
Cell Membrane ◽  
Tight Junction ◽  
Apical Cell ◽  
Apical Cell Membrane ◽  
Electrophysiological Properties ◽  
Basolateral Cell Membrane ◽  
Collecting Tubule ◽  
Conductive Properties ◽  
K Permeability ◽  
Cortical Collecting Tubule

The Na, K, and Cl conductive properties and the electrophysiological variability of the rabbit isolated cortical collecting tubule were assessed by evaluating the effect of single-ion substitutions on the transepithelial potential difference, Vte, and the transepithelial conductance, Gte. The Na permeability (and conductance) of the tight junction and basolateral cell membrane appeared to be low. However, a significant but variable amiloride-sensitive Na conductance was identified at the apical cell membrane. Although this Na conductance accounts for less than 10% of the Gte, variations in this conductance caused major alterations in the active transepithelial Na current and the Vte. A highly variable K permeability (and conductance) was also identified at the apical cell border and may account for some of the variability in Vte and Gte. This probably provides a pathway for K secretion from cell to lumen. The K permeability of the tight junction and basolateral cell membrane appeared to be relatively low. In contrast, the Cl permeability (and conductance) of the tight junction, and perhaps of the basolateral cell membrane, appeared to be high but variable and to account for the major fraction of the Gte and its variability. It is concluded that variations in the Na and K conductance of the apical cell membrane and the Cl conductance of the tight junction and basolateral cell membrane predominantly account for the variations in the electrophysiological properties of the cortical collecting tubule.

Characterization of apical cell membrane Na+ and K+ conductances of cortical collecting duct using microelectrode techniques

1984 ◽  
Vol 247 (1) ◽  
pp. F14-F24 ◽  
Author(s):  
R. G. O'Neil ◽  
S. C. Sansom
Keyword(s):  
Cell Membrane ◽  
Collecting Duct ◽  
Apical Cell ◽  
Membrane Voltage ◽  
Cortical Collecting Duct ◽  
Apical Cell Membrane ◽  
Basolateral Cell Membrane ◽  
Luminal Side ◽  
Conductive Properties ◽  
Microelectrode Techniques

The apical cell membrane ionic conductive properties of the isolated perfused rabbit cortical collecting duct (tubule) were assessed at 37 degrees C using microelectrode techniques. In the initial evaluation of the methodology, it was observed that stable cell membrane voltage recordings could be obtained by impaling cells either from the luminal side across the apical cell membrane or from the bath side across the basolateral cell membrane, providing initial evidence supporting the application of these techniques to this tissue. With the latter method of impalement, it was observed that addition of amiloride (50 microM) to the luminal perfusate caused a hyperpolarization of the apical cell membrane voltage, a decrease in the transepithelial conductance, and an increase in the fractional resistance (estimated as the ratio of the resistance of the apical cell membrane to the sum of apical and basolateral cell membrane resistances). These results are consistent with an amiloride-sensitive Na+ conductance at the apical cell border. In a similar manner it was deduced from the effects of elevating K+ in the luminal perfusate from 5 to either 25 or 50 mM that there was a high K+ conductance at the apical border. This conductive pathway was blocked by the luminal addition of 5 mM Ba2+ or reduction of the luminal pH to 4.0. Furthermore, since addition of both amiloride and Ba2+ to the perfusate caused the fractional resistance to increase from 0.52 +/- 0.04 to 0.91 +/- 0.03, the Na+ and K+ conductances are the apparent dominant conductive pathways at that border. It is concluded that microelectrode techniques can be applied successfully to the cortical collecting duct and that the apical cell membrane possesses an amiloride-sensitive Na+ conductance and a Ba2+- and H+-sensitive K+ conductance.

Intracellular microelectrode characterization of the rabbit cortical collecting duct

1983 ◽  
Vol 244 (1) ◽  
pp. F35-F47 ◽  
Author(s):  
B. M. Koeppen ◽  
B. A. Biagi ◽  
G. H. Giebisch
Keyword(s):  
Cell Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Fold Increase ◽  
K Channel ◽  
Cortical Collecting Duct ◽  
Apical Cell Membrane ◽  
Basolateral Cell Membrane

Cortical collecting ducts of the rabbit were perfused in vitro and the intracellular potential (Vbl) was measured with KCl-filled microelectrodes. The ratio of apical to basolateral membrane resistance (Ra/Rbl) was estimated from the voltage divider ratio using cable analysis. In control tubules Vbl averaged--84.0 +/- 2.5 mV and Ra/Rbl was 0.83 +/- 0.11. Pretreatment of the rabbits with mineralocorticoid caused Vbl to hyperpolarize to--105.8 +/- 3.1 mV and Ra/Rbl to decrease slightly to 0.62 +/- 0.10. A 10-fold increase of the luminal [K+] caused a 40.6 +/- 3.1 mV depolarization of Vbl in control tubules and a 33.0 +/- 4.2 mV depolarization in tubules from DOCA-pretreated rabbits. Concurrently, Ra/Rbl decreased in both groups, consistent with the existence of a conductive K+ channel at the apical cell membrane. This apical K+ channel was not sensitive to amiloride but was blocked by Ba2+. Conductive movement of Na+ across the apical membrane was also apparent in that Ra/Rbl increased with amiloride from 0.61 +/- 0.10 to 1.45 +/- 0.28. A 10-fold increase in the bath [K+] caused a 28.6 +/- 3.8 and a 49.4 +/- 4.4 mV depolarization of Vbl in tubules obtained from control and DOCA-pretreated rabbits, respectively. In both groups Ra/Rbl increased, suggesting that the basolateral cell membrane also contains a conductive K+ channel. Taken together the results support a model in which the transepithelial reabsorption of Na+ and the transepithelial secretion of K+ are driven by the Na+-K+-ATPase located in the basolateral cell membrane, with passive movement of these ions occurring through separate conductive pathways in the apical cell membrane.

Fine structure of the rectal papillae of the oriental fruuit fly, Dacus dorsalis Hendel (Tephritidae, Diptera Insecta)

1990 ◽  
Vol 48 (3) ◽  
pp. 498-499
Author(s):  
Len Wen-Yung ◽  
Mei-Jung Lin
Keyword(s):  
Fine Structure ◽  
Cell Membrane ◽  
Intercellular Space ◽  
Anterior Part ◽  
Apical Cell ◽  
Posterior Part ◽  
Apical Cell Membrane ◽  
Dacus Dorsalis ◽  
Radial Cell ◽  
Circular Base

Four cone-shaped rectal papillae locate at the anterior part of the rectum in Dacus dorsalis fly. The circular base of the papilla protrudes into the haemolymph (Fig. 1,2) and the rest cone-shaped tip (Fig. 2) inserts in the rectal lumen. The base is surrounded with the cuticle (Fig. 5). The internal structure of the rectal papilla (Fig. 3) comprises of the cortex with the columnar epithelial cells and a rod-shaped medulla. Between them, there is the infundibular space and many trabeculae connect each other. Several tracheae insert into the papilla through the top of the medulla, then run into the cortical epithelium and locate in the intercellular space. The intercellular sinuses distribute in the posterior part of the rectal papilla.The cortex of the base divides into about thirty segments. Between segments there is a radial cell (Fig. 4). Under the cuticle, the apical cell membrane of the cortical epithelium is folded into a regular border of leaflets (Fig. 5).

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