scholarly journals Renal glycerol metabolism and the distribution of glycerol kinase in rabbit nephron

1981 ◽  
Vol 198 (3) ◽  
pp. 543-549 ◽  
Author(s):  
G Wirthensohn ◽  
A Vandewalle ◽  
W G Guder
Keyword(s):  
Glycerol Kinase ◽  
The Other ◽  
Rabbit Kidney ◽  
Glycerol Metabolism ◽  
Kidney Cortex ◽  
Collagenase Treatment ◽  
Uptake Rates ◽  
Metabolic Products ◽  
Pars Recta ◽  
Convoluted Tubules

Glycerol and dihydroxyacetone are metabolized by rabbit kidney-cortex tubules, isolated by collagenase treatment. Half-maximal concentrations of both substrates were determined with regard to uptake rates and product formations. Maximal uptake rates were 643 and 329 mumol/h per g of protein for dihydroxyacetone and glycerol respectively. Glucose and lactate were found as major metabolic products. Glycerol kinase, the enzyme catalysing the first step in renal glycerol and dihydroxyacetone metabolism, was measured radiochemically as described by Newsholme, Robinson & Taylor [(1967) Biochim, Biophys. Acta 132, 338-346] and adapted for studies of the localization of this enzyme along the different structures of rabbit nephron. The results show that glycerol kinase is located exclusively in the proximal segments, i.e. the proximal convoluted tubules and the pars recta, but is negligible in the other structures studied. The activities were close to the maximal dihydroxyacetone uptake rates measured in tubule suspensions.

Electrical properties of rabbit early distal convoluted tubule in primary culture

1989 ◽  
Vol 257 (2) ◽  
pp. F288-F299 ◽  
Author(s):  
J. Merot ◽  
M. Bidet ◽  
B. Gachot ◽  
S. Le Maout ◽  
N. Koechlin ◽  
...  
Keyword(s):  
Primary Culture ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Transferase Activity ◽  
Gamma Glutamyl Transferase ◽  
Transport Pathway ◽  
Apical Side ◽  
Transepithelial Voltage ◽  
Glutamyl Transferase ◽  
Convoluted Tubules

Distal bright convoluted tubules (DCTb) were microdissected from rabbit kidney cortex and cultured in a hormonally defined medium. The quality and the degree of polarization of the growing epithelia were assessed by indirect immunofluorescence studies using a monoclonal antibody raised against the apical membrane of the DCTb in situ. The cultured monolayers had a high hexokinase activity and a low gamma-glutamyl transferase activity compared with cultured proximal convoluted tubules. Adenosine 3',5'-cyclic monophosphate production was stimulated by calcitonin and insensitive to parathyroid hormone, vasopressin, and isoproterenol. Both 20- and 30-day-old cultures developed an apical-negative transepithelial potential of -3.1 and -22.3 mV, respectively. Amiloride reversibly reduced the voltage by 90% only when applied on the apical side of the monolayers. Phenamil (10(-8), 10(-6) M) had the same effect as amiloride. Calcitonin reversibly decreased the transepithelial voltage. These data support the hypothesis that, in the DCTb in primary culture, the transepithelial voltage is due to the presence of Na channels and that calcitonin modulates this transport pathway.

Metabolism of C14-labeled substrates by rabbit kidney cortex and medulla

1962 ◽  
Vol 203 (1) ◽  
pp. 27-36 ◽  
Author(s):  
James B. Lee ◽  
Vernon K. Vance ◽  
George F. Cahill
Keyword(s):  
Fatty Acids ◽  
The Other ◽  
High Rate ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Anaerobic Conditions ◽  
Kidney Medulla ◽  
Bicarbonate Buffer ◽  
Radioactive Substrate

Slices of rabbit kidney cortex and medulla were incubated for 90 min at 38 C in Krebs-Ringer bicarbonate buffer containing C14 labeled substrate. In addition to substrate disappearance and concentrations of glycogen and fatty acids, measurements were made of the amount of radioactive substrate incorporated into CO2, glycogen, and fatty acids per gram of wet tissue. Glucose, fructose, mannose, glycerol, pyruvate, and palmitate were oxidized to a significantly greater extent by cortex than medulla. The concentration of glycogen in kidney medulla was twice that of cortex and was maintained at initial concentrations only in the presence of glucose, which showed a significantly greater incorporation into medullary glycogen than did the other substrates. Under pure anaerobic conditions simulating those in vivo, the present study suggests that the metabolism of medulla is almost exclusively glucose-dependent anaerobic glycolysis. On the other hand, the cortex is capable of utilizing a variety of substrates for a high rate of aerobic metabolism.

Quantitative Histochemistry of the Dog Nephron

1956 ◽  
Vol 185 (2) ◽  
pp. 372-376 ◽  
Author(s):  
W. P. McCann
Keyword(s):  
Alkaline Phosphatase ◽  
Lipid Content ◽  
Trypan Blue ◽  
The Other ◽  
Tissue Samples ◽  
Quantitative Histochemistry ◽  
Glucose Reabsorption ◽  
Pars Recta ◽  
Convoluted Tubules ◽  
Quantitative Chemical

Microdissection techniques for the separation of different anatomical segments of the dog nephron from frozen-dried kidney sections are described. Tissue samples thus isolated were suitable for quantitative chemical and enzymatic studies by precise microchemical methods. Trypan blue used as an intravital stain, served to distinguish proximal from distal convolutions, and did not alter the enzymes studied. Quantitative comparisons of water content, lipid content, and the activities of alkaline phosphatase, aldolase, fumarase, phosphohexoisomerase and hexokinase were made. The papilla differed from the other areas in lipid content. Alkaline phosphatase was localized mainly in the proximal convoluted tubules. The other enzymes varied less regularly from area to area. Hexokinase was four times higher in the pars recta of the proximal tubule than in any other area. Inasmuch as glucose reabsorption is believed to occur in the first half of the proximal convoluted tubule, the observed distribution of hexokinase does not further the hypothesis that this enzyme is concerned in glucose reabsorption by the kidney.

scholarly journals Energetics of renal Na+ and H+/l-alanine co-transport systems

1988 ◽  
Vol 256 (1) ◽  
pp. 299-302 ◽  
Author(s):  
H Jessen ◽  
H Vorum ◽  
K E Jørgensen ◽  
M I Sheikh
Keyword(s):  
Indirect Evidence ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Luminal Membrane ◽  
Alanine Transport ◽  
Pars Recta ◽  
Dependent Transport ◽  
Pars Convoluta ◽  
Convoluted Tubules

The stoichiometric properties of Na+- and H+-dependent L-alanine transporters recently identified in luminal-membrane vesicles prepared from proximal convoluted tubules (pars convoluta) and proximal straight tubules (pars recta) of rabbit kidney were studied. We provide indirect evidence suggesting that one Na+ and one H+ ion are co-transported with the L-alanine molecule via Na+-dependent and H+-dependent transport systems located in vesicles from pars convoluta. Furthermore, our experimental data suggest that both the high-affinity and the low-affinity Na+-dependent L-alanine transport systems of pars recta vesicles operate with a 1:1 stoichiometry.

scholarly journals Stoichiometric studies of β-alanine transporters in rabbit proximal tubule

1991 ◽  
Vol 277 (3) ◽  
pp. 891-894 ◽  
Author(s):  
H Jessen ◽  
M I Sheikh
Keyword(s):  
Indirect Evidence ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Coupling Ratio ◽  
Beta Alanine ◽  
Luminal Membrane ◽  
Straight Tubules ◽  
Pars Recta ◽  
Pars Convoluta ◽  
Convoluted Tubules

The coupling ratio for the transport of beta-alanine and Na+, H+ and Cl- in luminal membrane vesicles isolated from proximal convoluted tubules (pars convoluta) and proximal straight tubules (pars recta) of rabbit kidney was examined. Indirect evidence indicates that 1 H+ and approx. 2 Na+, 1 Cl- (Na(+)-dependent, high-affinity) or 1 Na+ (Na(+)-dependent, low-affinity) are co-transported with beta-alanine in the pars convoluta. In pars recta, the two Na(+)-dependent transporters exhibited the same stoichiometric properties respectively as in pars convoluta.

Glycerol metabolism in rabbits

1968 ◽  
Vol 46 (9) ◽  
pp. 1107-1114 ◽  
Author(s):  
Jean Himms-Hagen
Keyword(s):  
Turnover Rate ◽  
Glycerol Kinase ◽  
Rabbit Liver ◽  
Constant Infusion ◽  
Glycerol Dehydrogenase ◽  
Glycerol Metabolism ◽  
Utilization Rate ◽  
Glycerol Concentration ◽  
Glycerol Utilization ◽  
Fractional Turnover

The endogenous rate of glycerol production in rabbits was measured by several techniques: constant infusion of 1,3-14C-glycerol or 2-3H-glycerol or unlabeled glycerol; single injection of 1,3-14C-glycerol or 2-3H-glycerol or unlabeled glycerol. The rate was 5.5–11.6 μmoles/kg per minute (9 rabbits). The mean fractional turnover rate was 0.0585 ± 0.0052. During infusion of noradrenaline together with 3H-glycerol, the fractional turnover rate was no different from that in the absence of noradrenaline. The maximum utilization rate of glycerol was 28.1 ± 1.40 μmoles/kg per minute. The glycerol space was 58.1% of body weight. The relationship of glycerol concentration to rate of glycerol utilization in the intact rabbit suggests the existence of an enzyme with a KM for glycerol of 0.33 × 10−3 M; the glycerol kinase of rabbit liver was found to have a KM for glycerol of 0.29 × 10−3 M. This enzyme could account for the disappearance of glycerol in the intact animal except that its Vmax is only 4% of that expected. Possible reasons for this are discussed. A glycerol dehydrogenase with a Vmax similar to that of the glycerol kinase also exists in rabbit liver; its KM for glycerol is so high (0.5 M) that it is unlikely to play a significant role in glycerol metabolism in the normal rabbit.

Thermal Property Measurements on Biological Materials at Subzero Temperatures

1991 ◽  
Vol 113 (4) ◽  
pp. 423-429 ◽  
Author(s):  
Xuemei Bai ◽  
David E. Pegg
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
The Self ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Low Viscosity ◽  
Subzero Temperatures ◽  
Liquid Samples ◽  
Thermal Probes ◽  
Low Ionic Strength

The self-heated thermistor technique was used to measure the thermal conductivity and thermal diffusivity of biomaterials at low temperatures. Thermal standards were selected to calibrate the system at temperatures from −10°C to −70°C. The thermal probes were constructed with a convection barrier which eliminates convection inside liquid samples of low viscosity, without affecting the conductivity and diffusivity results. Using this technique, the thermal conductivity and diffusivity of two organ perfusates (HP5 and HP5 + 2M glycerol), one kidney phantom (a low ionic strength gel), as well as rabbit kidney cortex have been measured from −10°C to −70°C.

scholarly journals Amino acid transport in normal and glutathione-deficient sheep erythrocytes

1976 ◽  
Vol 154 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J D Young ◽  
J C Ellory ◽  
E M Tucker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Cell Types ◽  
The Other ◽  
Acid Transport ◽  
Sheep Erythrocytes ◽  
Uptake Rates

1. Uptake rates for 23 amino acids were measured for both normal (high-GSH) and GSH-deficient (low-GSH) erythrocytes from Finnish Landrace sheep. 2. Compared with high-GSH cells, low-GSH cells had a markedly diminished permeability to D-alanine, L-alanine, α-amino-n-butyrate, valine, cysteine, serine, threonine, asparagine, lysine and ornithine. Smaller differences were observed for glycine and proline, whereas uptake of the other amino acids was not significantly different in the two cell types.

Carbonic anhydrase XII mRNA encodes a hydratase that is differentially expressed along the rabbit nephron

2003 ◽  
Vol 284 (2) ◽  
pp. F399-F410 ◽  
Author(s):  
George J. Schwartz ◽  
Anne M. Kittelberger ◽  
Richard H. Watkins ◽  
Michael A. O'Reilly
Keyword(s):  
Carbonic Anhydrase ◽  
Transmembrane Protein ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Thick Ascending Limb ◽  
Basolateral Membranes ◽  
Collecting Ducts ◽  
Straight Tubules ◽  
Hydratase Activity

Membrane-bound carbonic anhydrase (CA) facilitates acidification in the kidney. Although most hydratase activity is considered due to CA IV, some in the basolateral membranes could be attributed to CA XII. Indeed, CA IV is glycosylphosphatidylinositol anchored, connoting apical polarization, but CA IV immunoreactivity has been detected on basolateral membranes of proximal tubules. Herein, we determined whether CA XII mRNA was expressed in acidifying segments of the rabbit nephron. The open reading frame of CA XII was sequenced from a rabbit kidney cortex cDNA library; it was 83% identical to human CA XII and coded for a 355-amino acid single-pass transmembrane protein. Northern blot analysis revealed an abundant 4.5-kb message in kidney cortex, medulla, and colon. By in situ hybridization, CA XII mRNA was expressed by proximal convoluted and straight tubules, cortical and medullary collecting ducts, and papillary epithelium. By RT-PCR, CA XII mRNA was abundantly expressed in cortical and medullary collecting ducts and thick ascending limb of Henle's loop; it was also expressed in proximal convoluted and straight tubules but not in glomeruli or S3 segments. FLAG-CA XII of ∼40 kDa expressed in Escherichia coli showed hydratase activity that was inhibited by 0.1 mM acetazolamide. Unlike CA IV, expressed CA XII activity was inhibited by 1% SDS, suggesting insufficient disulfide linkages to stabilize the molecule. Western blotting of expressed CA XII with two anti-rabbit CA IV peptide antibodies showed no cross-reactivity. Our findings indicate that CA XII may contribute to the membrane CA activity of proximal tubules and collecting ducts.

Sign in / Sign up

Export Citation Format

Share Document