scholarly journals Transport and metabolism of galactose in rat kidney cortex

1972 ◽  
Vol 129 (5) ◽  
pp. 1109-1118 ◽  
Author(s):  
Pamela D. McNamara ◽  
Stanton Segal

1. Analysis of transport of d-galactose was complicated by metabolism of the compound but appeared to have two components: a substrate-saturable component and a diffusion component. At low substrate concentration (<1mm) active transport was observed. Accumulation of galactose was largely independent of Na+concentration. The apparent Km for this component was 0.2mm. At substrate concentrations above 1mm the active transport system appeared saturated and further increases in substrate concentration resulted in a linear increase in the rate of galactose accumulation, but no concentration gradient was formed. 2. d-[1-14C]Galactose (2mm) was metabolized to14CO2 by rat kidney-cortex slices incubated at 37°C, at the rate of 68nmol/h per 100mg of tissue. 3. Intracellular components from such incubations were separated into a neutral fraction, the only major labelled component being galactose, and a phosphorylated fraction. 4. Phosphorylated metabolites found in galactose-incubated slices increased with increasing substrate concentration and achieved a limiting value of 0.42mm after 60min of incubation. 5. Galactose uptake was inhibited by anaerobiosis, dinitrophenol and phlorrhizin. 6. Methyl α-d-glucoside and d-glucose partially inhibited galactose uptake only at ratios of 100:1. 7. The presence of pyruvate did not decrease galactose metabolism although it did decrease production of14CO2 from [1-14C]galactose. Gluconeogenesis occurred in the presence of pyruvate and14C from galactose was found in glucose. 8. Rat kidney-cortex slices metabolized 2mm-[1-14C]galactonate to14CO2 at a rate of 20nmol/h per 100mg of tissue.

1958 ◽  
Vol 195 (2) ◽  
pp. 343-346 ◽  
Author(s):  
E. J. Støren

Active uptake of PAH by rat renal cortex slices was studied by the method of Cross and Taggart. Uptake was determined at low and at high medium concentrations of PAH. Pentobarbital sodium in concentrations comparable to those found in plasma during anesthesia, significantly depressed the uptake of PAH on all occasions. Simultaneously oxygen consumption was reduced. Acetate failed to stimulate PAH uptake in the presence of pentobarbital, although tissue respiration was restored to normal.


1984 ◽  
Vol 67 (5) ◽  
pp. 529-534 ◽  
Author(s):  
P. K. Wirdnam ◽  
R. D. G. Milner

1. Rat kidney cortex slices were incubated for 30 min at 37°C in unmodified Krebs-Henseleit buffer containing aldosterone, vasopressin, theophylline, ethacrynic acid, frusemide, spironolactone or ouabain. 2. Tamm—Horsfall glycoprotein (THG) released into the media was measured by radioimmunoassay and at the end of each experiment the slices were homogenized and assayed for THG content. 3. Incubation of kidney cortex slices in unmodified buffer resulted in a significant increase in the slice THG content when compared with pre-incubation levels. The increase was prevented by puromycin or cycloheximide. 4. Incubation in ethacrynic acid (1 mmol/l) or frusemide (10 mmol/l) resulted in a significant increase in release of THG when compared with unmodified buffer. Puromycin or cycloheximide failed to prevent the increased release. 5. THG release induced by ethacrynic acid or frusemide is probably the result of an aggregation-disaggregation reaction on the cell membrane. It is suggested that the action of the chloride inhibiting diuretics, ethacrynic acid and frusemide, is mediated in some way via THG.


1991 ◽  
Vol 14 (1-2) ◽  
pp. 42-47 ◽  
Author(s):  
Viera Spustov&aacute; ◽  
Rastislav Dz&uacute;rik

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