Ammoniagenesis in kidney cortex mitochondria of the rat: role of the mitochondrial dicarboxylate anion transporter

1978 ◽  
Vol 56 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Surinder Cheema-Dhadli ◽  
Mitchell L. Halperin
Keyword(s):  
Metabolic Acidosis ◽  
Renal Cortex ◽  
Rat Kidney ◽  
Maximum Velocity ◽  
Liver Mitochondria ◽  
Kidney Cortex ◽  
Chronic Metabolic Acidosis ◽  
Kidney Mitochondria ◽  
Anion Transporter

Since glutamine enters rat kidney mitochondria without exchange for an anion, the exit of its carbon skeleton must involve the dicarboxylate anion transporter (malate – inorganic phosphate) for ammoniagenesis to proceed. Therefore, this important mitochondrial anion transporter was studied in isolated renal cortex mitochondria. The phosphate concentration required for half-maximal rates of malate exit from renal cortex mitochondria of normal rats was 1.0 mM. This value was not decreased in renal cortex mitochondria from rats with chronic metabolic acidosis. The maximum velocity of the dicarboxylate transporter was not increased in renal cortex mitochondria from these acidotic rats. These kinetic parameters were similar in liver mitochondria. There was no acute activation of the dicarboxylate carrier when the incubation medium pH was lowered. Thus, there is no demonstrable activation of the dicarboxylate anion transporter in kidney cortex mitochondria of the rat with chronic metabolic acidosis. The significance of these results with respect to the regulation of renal ammoniagenesis is discussed.

Identification of an apical \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{Cl}^{-}{/}\mathrm{HCO}_{3}^{-}\) \end{document} exchanger in rat kidney proximal tubule

2003 ◽  
Vol 285 (3) ◽  
pp. C608-C617 ◽  
Author(s):  
Snezana Petrovic ◽  
Liyun Ma ◽  
Zhaohui Wang ◽  
Manoocher Soleimani
Keyword(s):  
Proximal Tubule ◽  
Apical Membrane ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Immunocytochemical Staining ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Kidney Proximal Tubule ◽  
Anion Transporter

SLC26A6 (or putative anion transporter 1, PAT1) is located on the apical membrane of mouse kidney proximal tubule and mediates [Formula: see text] exchange in in vitro expression systems. We hypothesized that PAT1 along with a [Formula: see text] exchange is present in apical membranes of rat kidney proximal tubules. Northern hybridizations indicated the exclusive expression of SLC26A6 (PAT1 or CFEX) in rat kidney cortex, and immunocytochemical staining localized SLC26A6 on the apical membrane of proximal tubules, with complete prevention of the labeling with the preadsorbed serum. To examine the functional presence of apical [Formula: see text] exchanger, proximal tubules were isolated, microperfused, loaded with the pH-sensitive dye BCPCF-AM, and examined by digital ratiometric imaging. The pH of the perfusate and bath was kept at 7.4. Buffering capacity was measured, and transport rates were calculated as equivalent base flux. The results showed that in the presence of basolateral DIDS (to inhibit [Formula: see text] cotransporter 1) and apical EIPA (to inhibit Na+/H+ exchanger 3), the magnitude of cell acidification in response to addition of luminal Cl– was ∼5.0-fold higher in the presence than in the absence of [Formula: see text]. The Cl–-dependent base transport was inhibited by ∼61% in the presence of 0.5 mM luminal DIDS. The presence of physiological concentrations of oxalate in the lumen (200 μM) did not affect the [Formula: see text] exchange activity. These results are consistent with the presence of SLC26A6 (PAT1) and [Formula: see text] exchanger activity in the apical membrane of rat kidney proximal tubule. We propose that SLC26A6 is likely responsible for the apical [Formula: see text] (and Cl–/OH–) exchanger activities in kidney proximal tubule.

Basolateral membrane H-OH-HCO3 transport in the proximal tubule

1989 ◽  
Vol 256 (5) ◽  
pp. F751-F765
Author(s):  
P. A. Preisig ◽  
R. J. Alpern
Keyword(s):  
Metabolic Acidosis ◽  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Respiratory Acidosis ◽  
Cell Voltage ◽  
Transport Mechanisms ◽  
Transport Capacity ◽  
Chronic Metabolic Acidosis

This review focuses on the basolateral membrane mechanisms of H-OH-HCO3 transport in the proximal tubule. The mechanism that has the greatest transport capacity and mediates most of transepithelial H-HCO3 transport is the electrogenic, Na-3HCO3 cotransporter. This transporter has been extensively characterized in the salamander, rat, and rabbit proximal tubule, and has now been found in a number of other epithelia that effect transepithelial NaHCO3 transport. Transporter rate is sensitive to intra- and extracellular [Na], intra- and extracellular [HCO3]/pH, and cell voltage. Adaptations in transporter activity have been demonstrated in chronic metabolic acidosis and alkalosis, chronic respiratory acidosis and alkalosis, and chronic hyperfiltration. In addition to the Na-3HCO3 cotransporter, the basolateral membrane possesses both Na-dependent and -independent Cl-HCO3 exchangers, a H leak, and in the S3 proximal tubule an Na-H antiporter. The role of these H-OH-HCO3 transport mechanisms in transcellular HCO3 and Cl absorption and pHi defense is discussed.

Inhibition of 25-hydroxyvitamin D3-1-hydroxylase by chronic metabolic acidosis

1982 ◽  
Vol 243 (4) ◽  
pp. E265-E271
Author(s):  
G. S. Reddy ◽  
G. Jones ◽  
S. W. Kooh ◽  
D. Fraser
Keyword(s):  
Vitamin D ◽  
Metabolic Acidosis ◽  
Rat Kidney ◽  
Ion Concentration ◽  
Hydroxylase Activity ◽  
Renal Metabolism ◽  
Dihydroxyvitamin D3 ◽  
Hydrogen Ion Concentration ◽  
Chronic Metabolic Acidosis ◽  
Negative Linear Correlation

Chronic metabolic acidosis had been shown to influence the renal metabolism of 25-hydroxyvitamin D3. Using the isolated perfused rat kidney model, we evaluated the rates of synthesis of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] in vitamin D-depleted [D(-)] and 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] in vitamin D-replete [D(+)] rats. Metabolic acidosis was induced in both groups of rats by feeding aqueous ammonium chloride for 9 days. Kidneys isolated from D(-) acidotic rats (mean pH, 7.11) exhibited a decreased rate of 1,25(OH)2D3 synthesis (0.79 +/- 0.17 pmol produce . h-1 . g kidney-1) when compared with that (1.27 +/- 0.09) of D(-) nonacidotic (mean pH, 7.33) rats. There was a significant negative linear correlation between the rate of synthesis of 1,25(OH)2D3 and the hydrogen ion concentration of the animal (r = 0.79, P less than 0.005). The rate of synthesis of 24,25(OH)2D3 by the kidneys from D(+) acidotic (mean pH, 7.06) and nonacidotic (mean pH, 7.39) rats did not differ (0.81 +/- 0.21 vs. 0.60 +/- 0.12 pmol product . h-1 . g kidney-1). It is concluded that chronic acidosis suppressed 1-hydroxylase activity, but does not suppress 24-hydroxylase activity.

Carbonic anhydrase II mRNA is induced in rabbit kidney cortex during chronic metabolic acidosis

1993 ◽  
Vol 265 (6) ◽  
pp. F764-F772 ◽  
Author(s):  
G. J. Schwartz ◽  
C. A. Winkler ◽  
B. J. Zavilowitz ◽  
T. Bargiello
Keyword(s):  
Metabolic Acidosis ◽  
Carbonic Anhydrase ◽  
Collecting Duct ◽  
Carbonic Anhydrase Ii ◽  
Northern Analysis ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Rt Pcr ◽  
Chronic Metabolic Acidosis ◽  
Pcr Product

Carbonic anhydrase II (CA II), the predominant isoform of carbonic anhydrase in the kidney, is believed to be localized primarily in the cytoplasm of proximal tubule and collecting duct intercalated cells. Carbonic anhydrase facilitates H+ secretion by catalyzing the formation of HCO3- from OH- in the presence of CO2. We have shown that renal cortical CA II activity is stimulated during 4-6 days of chronic metabolic acidosis [L.P. Brion, B.J. Zavilowitz, O. Rosen, and G.J. Schwartz. Am. J. Physiol. 261 (Regulatory Integrative Comp. Physiol. 30): R1204-R1213, 1991]. The purpose of these studies was to examine under similar conditions the regulation of CA II mRNA. We obtained a major portion of the rabbit CA II cDNA by reverse transcription of total RNA from rabbit kidney followed by amplification using oligonucleotide primers prepared from conserved areas in the coding regions of human, mouse, and chick CA II cDNAs in a polymerase chain reaction (RT-PCR). The 696-bp RT-PCR product was sequenced and found to be 71-86% homologous to CA II cDNAs from the other three species. The deduced amino acid sequence agreed closely (> 97%) with a previous Edman analysis of rabbit erythrocyte CA II. Northern analysis showed expression of a approximately 1.4 kb RNA, with cortex > outer medulla > inner medulla. Steady-state mRNA expression from kidney cortex of acid-treated rabbits was about twice that from controls, when normalized to the expression of beta-actin or malate dehydrogenase. The stimulation of CA II mRNA was greater after 3 days than after 5-6 days of acid treatment. (ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Pentobarbital Sodium on Uptake of PAH by Rat Kidney Cortex Slices in Vitro

1958 ◽  
Vol 195 (2) ◽  
pp. 343-346 ◽  
Author(s):  
E. J. Støren
Keyword(s):  
Oxygen Consumption ◽  
Renal Cortex ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Tissue Respiration ◽  
Rat Kidney Cortex ◽  
Pentobarbital Sodium ◽  
Cortex Slices ◽  
Kidney Cortex Slices

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.

Effect of arsenite on renal tissue slice metabolism in chronic metabolic acidosis and alkalosis

1979 ◽  
Vol 237 (2) ◽  
pp. F93-F99
Author(s):  
D. P. Simpson ◽  
J. Hecker
Keyword(s):  
Metabolic Acidosis ◽  
Renal Cortex ◽  
Renal Tissue ◽  
Tissue Slice ◽  
Tissue Slices ◽  
Chronic Metabolic Acidosis ◽  
14Co2 Production ◽  
The Difference ◽  
A Site

Tissue slices prepared from renal cortex of littermate dogs with chronic metabolic acidosis or alkalosis were incubated in media with or without arsenite and containing 1 mM L-[14C]glutamine or [1,5–14C]citrate. The presence of arsenite increased the concentration of alpha-ketoglutarate in slices by 5––20 times the values found without this inhibitor. alpha-Ketoglutarate concentrations in acidotic slices were 40% or more greater than those in alkalotic ones when arsenited was present. 14C incorporation into alpha-ketoglutarate was also increased manyfold by arsenite with either labeled glutamine or citrate as substrate. 14CO2 production from labeled glutamine by over 90% and from labeled citrate by over 75%; the difference between 14CO2 production by acidotic and alkalotic slices was greatly reduced or eliminated by arsenite. These results suggest that in chronic metabolic acidosis metabolism of both glutamine and citrate is stimulated at a site or sites preceding formation of alpha-ketoglutarate.

Chronic metabolic acidosis upregulates rat kidney Na-HCO 3 − cotransporters NBCn1 and NBC3 but not NBC1

2002 ◽  
Vol 282 (2) ◽  
pp. F341-F351 ◽  
Author(s):  
Tae-Hwan Kwon ◽  
Christiaan Fulton ◽  
Weidong Wang ◽  
Ira Kurtz ◽  
Jørgen Frøkiær ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Rat Kidney ◽  
Free Access ◽  
Thick Ascending Limb ◽  
Acid Base Balance ◽  
Acid Base ◽  
Chronic Metabolic Acidosis ◽  
Daily Water Intake ◽  
Base Balance ◽  
Access To Water

Several members of the Na-HCO[Formula: see text] cotransporter (NBC) family have recently been identified functionally and partly characterized, including rkNBC1, NBCn1, and NBC3. Regulation of these NBCs may play a role in the maintenance of intracellular pH and in the regulation of renal acid-base balance. However, it is unknown whether the expressions of these NBCs are regulated in response to changes in acid-base status. We therefore tested whether chronic metabolic acidosis (CMA) affects the abundance of these NBCs in kidneys using two conventional protocols. In protocol 1, rats were treated with NH4Cl in their drinking water (12 ± 1 mmol · rat−1 · day−1) for 2 wk with free access to water ( n = 8). Semiquantitative immunoblotting demonstrated that whole kidney abundance of NBCn1 and NBC3 in rats with CMA was dramatically increased to 995 ± 87 and 224 ± 35%, respectively, of control levels ( P < 0.05), whereas whole kidney rkNBC1 was unchanged (88 ± 14%). In protocol 2, rats were given NH4Cl in their food (10 ± 1 mmol · rat−1 · day−1) for 7 days, with a fixed daily water intake ( n = 6). Consistent with protocol 1, whole kidney abundances of NBCn1 (262 ± 42%) and NBC3 (160 ± 31%) were significantly increased compared with controls ( n = 6), whereas whole kidney rkNBC1 was unchanged (84 ± 17%). In both protocols, immunocytochemistry confirmed upregulation of NBCn1 and NBC3 with no change in the segmental distribution along the nephron. Consistent with the increase in NBCn1, measurements of pH transients in medullary thick ascending limb (mTAL) cells in kidney slices revealed two- to threefold increases in DIDS- sensitive, Na+-dependent HCO[Formula: see text] uptake in rats with CMA. In conclusion, CMA is associated with a marked increase in the abundance of NBCn1 in the mTAL and NBC3 in intercalated cells, whereas the abundance of NBC1 in the proximal tubule was not altered. The increased abundance of NBCn1 may play a role in the reabsorption of NH[Formula: see text] in the mTAL and increased NBC3 in reabsorbing HCO[Formula: see text].

scholarly journals Proteomic profiling and pathway analysis of the response of rat renal proximal convoluted tubules to metabolic acidosis

2013 ◽  
Vol 305 (5) ◽  
pp. F628-F640 ◽  
Author(s):  
Kevin L. Schauer ◽  
Dana M. Freund ◽  
Jessica E. Prenni ◽  
Norman P. Curthoys
Keyword(s):  
Metabolic Acidosis ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Pathological Condition ◽  
Rat Kidney ◽  
Proximal Convoluted Tubule ◽  
Kidney Cortex ◽  
Combined Processes ◽  
Proteomic Profiling ◽  
Rat Kidney Cortex ◽  
Cytosolic Proteins

Metabolic acidosis is a relatively common pathological condition that is defined as a decrease in blood pH and bicarbonate concentration. The renal proximal convoluted tubule responds to this condition by increasing the extraction of plasma glutamine and activating ammoniagenesis and gluconeogenesis. The combined processes increase the excretion of acid and produce bicarbonate ions that are added to the blood to partially restore acid-base homeostasis. Only a few cytosolic proteins, such as phosphoenolpyruvate carboxykinase, have been determined to play a role in the renal response to metabolic acidosis. Therefore, further analysis was performed to better characterize the response of the cytosolic proteome. Proximal convoluted tubule cells were isolated from rat kidney cortex at various times after onset of acidosis and fractionated to separate the soluble cytosolic proteins from the remainder of the cellular components. The cytosolic proteins were analyzed using two-dimensional liquid chromatography and tandem mass spectrometry (MS/MS). Spectral counting along with average MS/MS total ion current were used to quantify temporal changes in relative protein abundance. In all, 461 proteins were confidently identified, of which 24 exhibited statistically significant changes in abundance. To validate these techniques, several of the observed abundance changes were confirmed by Western blotting. Data from the cytosolic fractions were then combined with previous proteomic data, and pathway analyses were performed to identify the primary pathways that are activated or inhibited in the proximal convoluted tubule during the onset of metabolic acidosis.

Sign in / Sign up

Export Citation Format

Share Document