Sugar absorption and secretion by winter flounder intestine

1981 ◽  
Vol 240 (5) ◽  
pp. G392-G400
Author(s):  
R. J. Naftalin ◽  
A. Kleinzeller
Keyword(s):  
Sugar Transport ◽  
Winter Flounder ◽  
Transport Systems ◽  
Secretory Process ◽  
Free Sugar ◽  
Pseudopleuronectes Americanus ◽  
Experimental Conditions ◽  
Sugar Absorption ◽  
Net Flux ◽  
Secretory System

Transport of sugars by winter flounder (Pseudopleuronectes americanus) intestine has been examined, and the following observations have been made. 1) No net absorption of D-galactose was found in controls; however, mucosally applied 0.1 mM phlorizin stimulated the mucosal-serosal flux with net sugar secretion. 2) Net absorption of methyl glycosides was inhibited by D-galactose, 0.1 mM ouabain, and phlorizin (without induction of secretion). 3) Net secretion of 2-deoxy-D-galactose was found without cellular accumulation of free sugar. The secretory process had a Km of 10 mM and was inhibited by serosally applied 0.1 mM phloretin, bilateral replacement of Ringer Na+ by choline, serosal ouabain, and D-galactose. 4) No net absorption or secretion of 2-deoxy-D-glucose was found with a variety of experimental conditions. 5) At least two active transport systems for sugars appear to be operative in the flounder intestine: a conventional Na+-dependent sugar transport system across the brush border that allows net absorption and a Na+-dependent secretory system that apparently also operates across the mucosal border. Because D-galactose is transported by both systems, there is no net flux of this sugar. Several possible models for the net secretory system are discussed.

Renal sugar transport in the winter flounder: V. secretion of 2-deoxy-D-galactose

1978 ◽  
Vol 234 (5) ◽  
pp. F424-F431
Author(s):  
J. B. Pritchard ◽  
G. Booz ◽  
A. Kleinzeller
Keyword(s):  
Sugar Transport ◽  
Winter Flounder ◽  
Free Sugar ◽  
Renal Tubules ◽  
Pseudopleuronectes Americanus ◽  
Clearance Ratio ◽  
Renal Handling ◽  
Cell Clearance

Isolated renal tubules and renal clearance techniques were used to characterize the renal handling of 2-deoxy-D-galactose (2-d-Gal) by the winter flounder (Pseudopleuronectes americanus). In vitro, energy-dependent, pH-sensitive uptake of 2-d-Gal (2–100 micron) was seen at the antiluminal face of the cell. Clearance measurements showed net secretion of 2-d-Gal in vivo. The mean clearance of 2-d-Gal in 18 fish was 0.98 +/- 0.16 ml/h while the glomerular filtration rate (GFR) was only 0.37 +/- 0.10 ml/h. Secretion was associated with marked renal accumulation of both 2-d-Gal and phosphorylated derivatives (2-d-Gal-1-phosphate). Tissue-to-plasma ratios (T/P) averaged 19 for free sugar and 59 for total sugar. Both clearance ratio and T/P were reduced to approximately 1 by injection of galactose (2.5 mmol/kg) simultaneously with 2-d-Gal (25 mumol/kg). Phlorizin (2.5 mumol/kg) increased net 2-d-Gal secretion, whereas glucose (2.5 mmol/kg) produced no change in secretion. Both compounds depressed 2-d-Gal T/P. This result suggests the presence of readsorptive transport at the brush border, sensitive to glucose and phlorizin.

Renal sugar transport in the winter flounder. I. Renal clearance studies

1976 ◽  
Vol 231 (2) ◽  
pp. 603-607 ◽  
Author(s):  
JB Pritchard ◽  
A Kleinzeller
Keyword(s):  
Renal Tubule ◽  
Sugar Transport ◽  
Renal Tissue ◽  
Total Sugar ◽  
Winter Flounder ◽  
Free Sugar ◽  
Pseudopleuronectes Americanus ◽  
Renal Handling ◽  
Luminal Membrane ◽  
Clearance Studies

The renal handling of several sugars was examined using clearance techniques in the winter flounder Pseudopleuronectes americanus. The nonmetabolizable sugar alpha-methyl-D-glucoside was extensively reabsorbed, with consequent accumulation in renal tissue to nearly twice plasma concentration. Both glucose and phlorizin abolished reabsorption and reduced tissue-to-plasma ratios (T/P). D-Galactose was reabsorbed. However, the T/P for free galactose was only 0.6 (total sugar was 1.7). Glucose and phlorizin produced only a transient decrease in reabsorption and no change in T/P. 2-Deoxy-D-glucose showed neither net reabsorption nore secretion. Nevertheless, kidney T/P were inexcess of 6 for total sugar and 1.2 for free sugar, indicating entry through the peritubular face of the tubule. Neither glucose nor phlorizin altered 2-deoxy-D-glucose clearance, but both reduced T/P for total sugar (2.4) and free sugar (0.7). Thus, several systems govern the handling of these sugars at the luminal membrane of the renal tubule, just as has been previously demonstrated at the peritubular membrane in this species.

Renal sugar transport in the winter flounder. II. Galactose transport system

1976 ◽  
Vol 231 (2) ◽  
pp. 608-613 ◽  
Author(s):  
A Kleinzeller ◽  
GR Dubyak ◽  
JM Mullin
Keyword(s):  
Sugar Transport ◽  
Basal Membrane ◽  
Ring Structure ◽  
Close Packing ◽  
Winter Flounder ◽  
Sugar Uptake ◽  
Renal Tubules ◽  
Pseudopleuronectes Americanus ◽  
Galactose Transport ◽  
Hexose Carrier

The structural specificity of the transport of 0.5 mM D-galactose and 2-deoxy-D-galactose by teased renal tubules of the winter flounder Pseudopleuronectes americanus was investigated. The sugar uptake reflects preponderantly transport at the antiluminal membrane of tubular cells. Both sugars compete for the transport sites, indicating the sharing of a common carrier. 1) The structural requirements for the hexose-carrier interaction were defined by an inhibiton analysis using 12 structurally analogous sugars (5 mM): a (pyranose) ring structure; a free hydroxyl on C1; free hydroxyls (equatorial configuration) on C3 and C4; an oxygen on C6. Close packing in the vicinity of C2 is indicated. 2) Consonant with the requirement of a free C1-OH, beta-methyl-D-galactoside is not transported 3) Increasing concentrations (0.05-0.5 mM) of phlorizin and phloretin inhibit sugar uptake by lowering cellular levels of phosphorylated hexoses, whereas the levels of free sugars are not depressed. The possibility of an interaction of the sugar at C1-0H with a phosphorylated group at the carrier as the first step in the translocation process of both hexoses across the basal membrane is raised.

Organic cation secretion in flounder renal tissue

1987 ◽  
Vol 253 (6) ◽  
pp. R861-R867 ◽  
Author(s):  
D. S. Miller ◽  
P. D. Holohan
Keyword(s):  
Glomerular Filtration Rate ◽  
Steady State ◽  
Filtration Rate ◽  
Organic Cation ◽  
Renal Tissue ◽  
Winter Flounder ◽  
Organic Cations ◽  
Pseudopleuronectes Americanus ◽  
Renal Tubular ◽  
Secretory System

In the winter flounder, Pseudopleuronectes americanus, renal clearance experiments showed that the model organic cations, tetraethylammonium (TEA) and N'-methylnicotinamide (NMN), were strongly secreted; organic cation-to-polyethylene glycol (glomerular filtration rate marker) clearance ratios averaged 130 and 30, respectively. TEA uptake by isolated renal tubular masses was concentrative and saturable. Transport was inhibited by competitor organic cations and reduced by exposure to NaCN,2,4-dinitrophenol, ouabain, and HgCl2. Organic anions did not reduce TEA uptake. NMN was the poorest inhibitor of TEA uptake of all the organic cations tested. In addition, the rate of NMN uptake was slower than that of TEA, and the steady-state tissue-to-medium ratio was lower (5 for NMN vs. 10 for TEA; both at 25 microM). The data show the presence of an organic cation secretory system in flounder tissue that resembles the mammalian systems in several respects.

Renal sugar transport in the winter flounder. VI. Reabsorption of D-mannose

1982 ◽  
Vol 242 (4) ◽  
pp. F415-F422 ◽  
Author(s):  
J. B. Pritchard ◽  
G. W. Booz ◽  
A. Kleinzeller
Keyword(s):  
Plasma Concentrations ◽  
Sugar Transport ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Paralichthys Lethostigma ◽  
Southern Flounder ◽  
Cotransport System ◽  
Stimulation Experiments

The transport of D-mannose (Man) in flounder kidney was studied using renal clearance techniques in vivo and brush border membrane (BBM) vesicles in vitro. At plasma concentrations of 50-100 microM Man, the winter flounder (Pseudopleuronectes americanus) reabsorbed up to 70% of the filtered sugar. Man phosphates, but not free Man, accumulated in renal cells. Reabsorption of Man was reduced by phlorizin, D-glucose, methyl-alpha-D-glucoside, methyl-alpha-D-mannoside, and 2-deoxy-D-glucose. In BBM vesicles a Na+-dependent, phlorizin-sensitive overshoot in Man uptake (10 microM) was seen. Na+-dependent Man uptake was saturable, with an apparent Km of 127 microM. The transport properties for Man were identical in BBM vesicles from the winter flounder and southern flounder (Paralichthys lethostigma). The transport specificity was determined by cis-inhibition and trans-stimulation experiments with BBM. Glucose, galactose, 1,5-anhydro-D-mannitol (i.e., 1-deoxymannose), 2-deoxy-2-fluoro-D-glucose, and methyl-alpha-mannoside were shown to share the carrier-mediating mannose transport. 2-Deoxyglucose, methyl-alpha-2-deoxy-D-glucoside, and both the isomers (alpha and beta) of methyl-D-glucoside did not. In contrast, alpha-methyl-D-glucoside inhibited D-glucose transport both in vivo and in BBM vesicles. It is concluded that Man reabsorption in the flounder occurs via a Na+-cotransport system that also handles glucose but that differs from the glucose/methyl-alpha-D-glucoside reabsorptive pathway in that 1) an oxygen on C-1 is not required, and 2) an axial configuration for -OH on C-2 (C1 conformation) is readily accommodated.

Renal sugar transport in the winter flounder. III. Two glucose transport systems

1977 ◽  
Vol 232 (3) ◽  
pp. F227-F234 ◽  
Author(s):  
A. Kleinzeller ◽  
G. R. Dubyak ◽  
P. M. Griffin ◽  
E. M. McAvoy ◽  
J. M. Mullin ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Glucose Transport ◽  
Transport System ◽  
Sugar Transport ◽  
Winter Flounder ◽  
Transport Systems ◽  
Renal Tubules ◽  
Pyranose Ring ◽  
Structural Requirements ◽  
Specificity Pattern

Teased renal tubules of the winter flounder (Pseudopleuronectes americanus) were employed to investigate the structural requirements for two pathways of D-glucose transport which take place preponderantly across the basal (antiluminal) face of renal cells. 1) An inhibition analysis of the equilibrating, Na-independent and phlorizin-sensitive transport of the nonmetabolizable methyl-alpha-D-glucoside (0.1 and 0.5 mM), with 20 glucose analogs (5 mM), was employed to establish the structural requirements for the substrate-carrier interaction: a (pyranose) ring, oxygen, or F at C1, C2-OH, C3-OH, and C4-OH (all axial, 1C model). Some interaction may also occur at C6-OH. D-Glucose shares this transport system. Hydrogen bonding between the oxygens and the carrier is suggested. 2) The phloretin- and phlorizin-sensitive, ouabain-insensitive transport of D-glucose, 2-deoxy-D-glucose, and D-mannose is associated with considerable phosphorylation. The three sugars mutually compete for a shared transport site. The specificity pattern characterizing the transport system defines the following structural requirements: a (pyranose) ring, a free C1-OH, C3-OH, and C4-OH (both axial) and possibly C6-OH. Hydrogen bonding between the carrier and the oxygens at C3, C4, and C6, and covalent bonding at C1 is suggested.

Renal proximal tubule of flounder. I. Physiological properties

1986 ◽  
Vol 250 (4) ◽  
pp. R608-R615 ◽  
Author(s):  
K. W. Beyenbach ◽  
D. H. Petzel ◽  
W. H. Cliff
Keyword(s):  
Epithelial Transport ◽  
Winter Flounder ◽  
Transport Systems ◽  
Pseudopleuronectes Americanus ◽  
Physiological Properties ◽  
Secretory Transport ◽  
Transepithelial Voltage ◽  
Electrochemical Potentials ◽  
Leaky Epithelium

The proximal segment of the winter flounder, Pseudopleuronectes americanus, was investigated. Isolated tubules net secrete fluid, although at low rates, 37 pl X min-1 X mm-1. The dominant ions in secreted fluid are Na and Cl, with [Cl] significantly higher than in the bath. Mg and SO4 concentrations in secreted fluid are more than 10-fold greater than in the bath. The transepithelial voltage (-1.9 mV) and resistance (26 omega X cm2) indicate an electrically leaky epithelium, and transepithelial diffusion potentials suggest the Na selectivity of the paracellular pathway. Transepithelial electrochemical potentials point to active transport of Mg, SO4, and probably also Cl and to transepithelial equilibrium of Na. Failure to observe any secretory transport in tubules perfused in vitro at the commonly used perfusion rates illustrates the necessity of low, preferably subnanoliter, perfusion rates in detecting and studying low-capacity epithelial transport systems by the method of Burg.

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