Effect of metabolic acidosis and alkalosis on NEM-sensitive ATPase in rat nephron segments

1992 ◽  
Vol 262 (4) ◽  
pp. F583-F590 ◽  
Author(s):  
C. Khadouri ◽  
S. Marsy ◽  
C. Barlet-Bas ◽  
L. Cheval ◽  
A. Doucet
Keyword(s):  
Metabolic Acidosis ◽  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Nephron Segments ◽  
Medullary Thick Ascending Limb ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Nephron Segment ◽  
Electrogenic Proton Pump ◽  
Chloride Treatment

An N-ethylmaleimide (NEM)-sensitive adenosinetriphosphatase (ATPase) displaying the kinetic and pharmacological properties of an electrogenic proton pump has been described in the different segments of rat nephron, where it mediates part of the active tubular proton secretion. This study was therefore designed to evaluate whether changes in urinary acidification observed during metabolic acidosis or alkalosis were associated with alterations of the activity of tubular NEM-sensitive ATPase, and if so, to localize the nephron segments responsible for these changes. Within 1 wk after the onset of ammonium chloride treatment, rats developed a metabolic acidosis, and NEM-sensitive ATPase activity was markedly increased in the medullary thick ascending limb of Henle's loop and outer medullary collecting tubule, and slightly increased in the cortical collecting tubule. Conversely, treatment with sodium bicarbonate induced a metabolic alkalosis that was accompanied by decreased NEM-sensitive ATPase activity in medullary thick ascending limb and outer medullary collecting tubule. NEM-sensitive ATPase activity was not altered in any other nephron segment tested in alkalotic and acidotic rats, i.e., the proximal tubule and the cortical thick ascending limb of Henle's loop. Changes qualitatively similar were observed as soon as 3 h after the onset of NaHCO3 or NH4Cl-loading. In the medullary collecting tubule, alterations of NEM-sensitive ATPase activity are in part due to hyperaldosteronism observed in both acidotic and alkalotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Na-K-ATPase activity along the rabbit, rat, and mouse nephron

1979 ◽  
Vol 237 (2) ◽  
pp. F114-F120 ◽  
Author(s):  
A. I. Katz ◽  
A. Doucet ◽  
F. Morel
Keyword(s):  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Sensitivity Limit ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Pars Recta ◽  
Hydrolysis Of ◽  
Total Enzyme

Na-K-ATPase activity along the rabbit, rat, and mouse nephron was determined with a micromethod that measures directly labeled phosphate released by the hydrolysis of [gamma-32P]ATP. Na-K-ATPase activity was highest in the rat, intermediate in the mouse, and lowest in the rabbit nephron. With the exception of rabbit cortical thick ascending limb, the enzyme profile was similar in the three species: Na-K-ATPase activity per millimeter tubule length was highest in the distal convoluted tubule and thick ascending limb of Henle's loop, intermediate in the proximal convoluted tubule, and lowest in the pars recta and collecting tubule. The enzyme was present in the thin limbs of Henle's loop, but its activity was very low and measurements were close to the sensitivity limit of the method. Both the absolute activity and the fraction of the total enzyme represented by Na-K-ATPase were severalfold higher than in kidney homogenates. Finally, the Na-K-ATPase activity measured in certain segments of the rat and rabbit nephron in this study seems sufficient to account in theory for the active component of the net sodium transport found in the corresponding region of the nephron with either in vivo or in vitro single tubule microperfusion techniques.

Difference in the Na affinity of Na(+)-K(+)-ATPase along the rabbit nephron: modulation by K

1990 ◽  
Vol 259 (2) ◽  
pp. F246-F250 ◽  
Author(s):  
C. Barlet-Bas ◽  
L. Cheval ◽  
C. Khadouri ◽  
S. Marsy ◽  
A. Doucet
Keyword(s):  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Kidney Cells ◽  
Nephron Segments ◽  
Adaptive Property ◽  
Collecting Tubule ◽  
Pump Activity ◽  
K Concentration ◽  
Cortical Collecting Tubule

The sensitivity of Na(+)-K(+)-ATPase to Na was determined in single segments of rabbit nephron isolated by microdissection. In the cortical collecting tubule (CCT), Na(+)-K(+)-ATPase was threefold more sensitive to Na (apparent K0.5 approximately 3 mM) than in proximal convoluted tubule and cortical thick ascending limb (apparent K0.5 approximately 10 mM). Furthermore, increasing K concentration from 5 to greater than 100 mM markedly reduced the affinity of the pump for Na in all three nephron segments. In fact, the main shift in Na affinity occurred when K changed from 100 to 120 mM; in the CCT, increasing K concentration from 100 to 120 mM while maintaining Na concentration at 10 mM reduced Na(+)-K(+)-ATPase activity by greater than 35%. These findings confirm that, in kidney cells as in other cells, intracellular Na limits the rate of Na(+)-K(+)-ATPase. Thus any alteration of intracellular Na concentration modifies the pump activity in a way that contributes to the restoration of intracellular Na homeostasis. This adaptive property is particularly efficient in the collecting tubule in which the apparent K0.5 of the pump for Na is close to normal intracellular Na concentration. Furthermore, changes in intracellular K concentration, which usually accompany those of Na so as to maintain the total cation concentration constant, potentiate the regulatory role of Na through modifications of its affinity for the pump.

Glucocorticoid effects on Na-K-ATPase in rabbit nephron segments

1985 ◽  
Vol 248 (4) ◽  
pp. F487-F491
Author(s):  
L. C. Garg ◽  
N. Narang ◽  
C. S. Wingo
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Type I ◽  
Thick Ascending Limb ◽  
Nephron Segments ◽  
Medullary Thick Ascending Limb ◽  
Significant Difference ◽  
Straight Tubules ◽  
And Control ◽  
Control Sham

We determined the effect of dexamethasone on Na-K-ATPase activity in six nephron segments of the adrenalectomized rabbit. Treatment consisted of 1.4 micrograms dexamethasone X 100 g body wt-1 X day-1 for 7 days prior to the study of the nephron segments. Enzyme activity was determined in individual nephron segments by a microfluorometric assay. There was 40-50% less activity of Na-K-ATPase in the S1 portion of the proximal convoluted tubule (PCT, S1), the medullary thick ascending limb (MTAL), and the distal convoluted tubule (DCT) of adrenalectomized rabbits compared with that of control (sham-operated) animals. There was no significant difference in the enzyme activity in proximal straight tubules (PST, S2 and S3) and cortical thick ascending limb (CTAL) of adrenalectomized and control animals. Dexamethasone treatment produced a dexamethasone concentration of 5 +/- 0.8 nM in the plasma and increased Na-K-ATPase activity in PCT (S1), MTAL, and DCT of the adrenalectomized animals to the control levels without significantly affecting the enzyme activity in the PST (S2, S3) or CTAL. The concentration of dexamethasone in the plasma was such that the hormone should bind mainly to dexamethasone receptors (Kd = 5 nM) and very little to aldosterone receptors (Kd greater than 60 nM). Thus, glucocorticoids probably stimulate Na-K-ATPase in PCT, MTAL, and DCT through glucocorticoid (Type II) receptors and not through mineralocorticoid (Type I) receptors.

Stimulation of Na+/K+-ATPase activity by polyamines in the rat renal medullary cells of the thick ascending limb of Henle's loop

1990 ◽  
Vol 127 (3) ◽  
pp. 377-382 ◽  
Author(s):  
J. A. Charlton ◽  
P. H. Baylis
Keyword(s):  
Atpase Activity ◽  
Arginine Vasopressin ◽  
Thick Ascending Limb ◽  
Stimulus Response ◽  
Spermine Synthase ◽  
Medullary Thick Ascending Limb ◽  
Henle's Loop ◽  
Specific Inhibitors ◽  
Stimulation Of

ABSTRACT Previous studies have indicated that ornithine decarboxylase (ODC) may be involved in the stimulation of Na+/K+-ATPase activity by arginine vasopressin (AVP) in the rat renal medullary thick ascending limb of Henle's loop. The present study was aimed at establishing the role of the polyamines, the conversion products of ODC activity, in the stimulation of Na+/K+-ATPase by AVP. Using cytochemical methods, we have demonstrated an increase in Na+/K+-ATPase activity after stimulation with putrescine, spermidine and spermine (each 1 mmol/l) for 2·5,2 and 1·5 min respectively. The specific inhibitors of spermidine and spermine synthase, bis-cyclohexylammonium sulphate and N-alkylated-1,3-diaminopropane respectively, inhibited the stimulation of Na+/K+-ATPase by AVP, this inhibition being reversed by spermine. These findings suggest that polyamines are involved in the stimulus-response coupling of the hormone-mediated response. Journal of Endocrinology (1990) 127, 377–382

Enhanced glomerular filtration and Na+-K+-ATPase with furosemide administration

1987 ◽  
Vol 252 (5) ◽  
pp. F910-F915 ◽  
Author(s):  
P. Scherzer ◽  
H. Wald ◽  
M. M. Popovtzer
Keyword(s):  
Glomerular Filtration ◽  
Collecting Duct ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Nephron Segments ◽  
Medullary Thick Ascending Limb ◽  
Henle's Loop ◽  
Proximal Straight Tubule ◽  
X 24 ◽  
Furosemide Administration

To evaluate the effect of furosemide on kidney function, glomerular filtration rate (GFR), urinary Na excretion (UNaV), Na reabsorption (NAR), and Na+-K+-ATPase in isolated nephron segments were measured in 1) rats treated with furosemide 10 mg X 100 g-1 X 24 h-1 ip for 7 days, and 2) rats receiving an oral Na load for 12 days. In furosemide-treated rats, GFR rose from 0.61 +/- 0.03 (mean +/- SD) to 0.83 +/- 0.06 ml/min (P less than 0.01), UNaV rose from 904 +/- 71 to 1,402 +/- 85 mueq/day (P less than 0.001), and net NAR rose from 87.5 +/- 3.7 to 116.7 +/- 9.0 mueq/min (P less than 0.01). Na+-K+-ATPase remained unchanged in the proximal convoluted tubule (PCT), proximal straight tubule (PST), cortical thick ascending limb of Henle's loop (cTALH), and medullary thick ascending limb of Henle's loop (mTALH), but was increased in the distal convoluted tubule (DCT) and in cortical collecting duct (CCD) from 48.5 +/- 1.2 to 75.3 +/- 0.7 (P less than 0.001) and from 18.6 +/- 0.7 to 27.1 +/- 2.7 (P less than 0.02) X 10(-11) mol X mm-1 X min-1, respectively. In Na-loaded rats GFR rose from 0.61 +/- 0.04 to 0.86 +/- 0.03 ml/min (P less than 0.001), UNaV rose from 1,064 +/- 118 to 18,532 +/- 2,045 mueq/day (P less than 0.001), net NAR from 88.1 +/- 3.0 to 107.8 +/- 3.9 mueq/min and Na-K-ATPase in the mTALH rose from 40.3 +/- 1.4 to 56.2 +/- 2.11 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Cloning, renal distribution, and regulation of the rat Na+- HCO 3 − cotransporter

1998 ◽  
Vol 274 (6) ◽  
pp. F1119-F1126 ◽  
Author(s):  
Charles E. Burnham ◽  
Michael Flagella ◽  
Zhaohui Wang ◽  
Hassane Amlal ◽  
Gary E. Shull ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Rat Kidney ◽  
Human Kidney ◽  
Cloning And Expression ◽  
Thick Ascending Limb ◽  
Mrna Levels ◽  
Reading Frame ◽  
Medullary Thick Ascending Limb ◽  
Nephron Segment

We recently reported the cloning and expression of a human kidney Na+-[Formula: see text]cotransporter (NBC-1) (C. E. Burnham, H. Amlal, Z. Wang, G. E. Shull, and M. Soleimani. J. Biol. Chem. 272: 19111–19114, 1997). To expedite in vivo experimentation, we now report the cDNA sequence of rat kidney NBC-1. In addition, we describe both the organ and nephron segment distributions and the regulation of NBC-1 mRNA under three models of pH stress: chloride-depletion alkalosis (CDA), metabolic acidosis, and bicarbonate loading. Rat NBC-1 cDNA encodes an open reading frame of 1,035 amino acids, with 96 and 87% identity to human and salamander NBC-1, respectively. Rat NBC-1 mRNA is expressed at high levels in kidney and brain, with lower levels in colon, stomach, and heart. None appears in liver. In the kidney, NBC-1 is expressed mainly in the proximal tubule, with traces found in medullary thick ascending limb and papilla. [Formula: see text] loading decreased NBC-1 mRNA levels, which were unchanged either by metabolic acidosis or by CDA.

Stimulation of rat renal medullary Na+/K+-ATPase by arginine vasopressin is mediated by the V2 receptor

1990 ◽  
Vol 127 (2) ◽  
pp. 213-216 ◽  
Author(s):  
J. A. Charlton ◽  
P. H. Baylis
Keyword(s):  
Atpase Activity ◽  
Arginine Vasopressin ◽  
Thick Ascending Limb ◽  
Medullary Thick Ascending Limb ◽  
Henle's Loop ◽  
Cytochemical Bioassay ◽  
V2 Receptor ◽  
Stimulation Of

ABSTRACT In previous studies, we have demonstrated that 1–10 fmol arginine vasopressin (AVP)/l maximally stimulates the activity of the enzyme Na+/K+-ATPase in the rat renal medullary thick ascending limb (MTAL) of Henle's loop after 4 or 10 min of stimulation when measured using a cytochemical bioassay. We have tested the hypothesis that this stimulation is mediated by the V2 receptor in the MTAL. A cytochemical bioassay was used to investigate the effect of specific V1 and V2/V1 antagonists and a synthetic V2 agonist [1-deamino,8-d-arginine]-vasopressin (dDAVP), on the activity of Na+/K+-ATPase. There was no effect of the V1 antagonist (1 fmol-1 μmol/l) in inhibiting the activity of Na+/K+-ATPase stimulated by 1 fmol AVP/l. In contrast, 100 pmol of the V2/V1 antagonist/l significantly (P < 0·001) inhibited the stimulation of Na+/K+-ATPase activity by 1 fmol AVP/l from 55·5±4·3 (s.e.m.) to 31·9±1·6 mean integrated extinction (MIE) after 4 min of stimulation and from 67·0±3·2 to 36·9±0·7 MIE after 10 min of stimulation. Similarly, the stimulation of Na+/K+-ATPase by 10 fmol dDAVP/l was inhibited by the V2/V1 antagonist from 55·1±1·0 to 26·1±0·5 MIE after 4 min of stimulation. We conclude that the stimulation of Na+/K+-ATPase by AVP is mediated by the V2 receptor in the rat renal MTAL. Journal of Endocrinology (1990) 127, 213–216

Regulation of renal Na-K-ATPase in the rat: effect of uninephrectomy

1986 ◽  
Vol 251 (3) ◽  
pp. F506-F512 ◽  
Author(s):  
S. K. Mujais ◽  
N. A. Kurtzman
Keyword(s):  
Enzyme Activity ◽  
Adrenal Gland ◽  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Medullary Thick Ascending Limb ◽  
Collecting Tubule ◽  
Pars Recta ◽  
Intact Rats ◽  
Cortical Collecting Tubule

This study has examined the temporal profile and the segmental localization along the rat nephron of the increase in Na-K-ATPase produced by uninephrectomy, and the role of the adrenal gland in the generation of the increase in enzyme activity. In adrenal-intact rats, an increase in Na-K-ATPase activity in the cortical collecting tubule (CCT) was observed at 1 wk (140 +/- 13% of sham, P less than 0.05) and sustained at 2 wk (140 +/- 8% of sham, P less than 0.05). In contrast, the enhancement of enzyme activity in the proximal convoluted tubule (PCT) was transient (at 1 wk: 164 +/- 20% of sham, P less than 0.05; and at 2 wk: 97 +/- 9% of sham, P greater than 0.5). No changes in Na-K-ATPase activity were observed in the other nephron segments studied: pars recta, medullary thick ascending limb, cortical thick ascending limb, distal convoluted tubule, and medullary collecting tubule. In adrenalectomized rats, CCT enzyme activity was lower than in adrenal-intact rats (761 +/- 84 vs. 1,984 +/- 276 pmol X mm-1 X h-1, P less than 0.001) and was not altered by uninephrectomy (849 +/- 91 pmol X mm-1 X h-1, NS). We conclude that the increase in Na-K-ATPase activity following uninephrectomy is restricted to two segments of the nephron and follows a distinctive pattern in each. In the PCT a transient enhancement in enzyme activity is observed, whereas in the CCT the increase in Na-K-ATPase is sustained and requires the presence of an intact adrenal gland.

Changes in tubular basolateral membrane markers after chronic DOCA treatment

1983 ◽  
Vol 245 (1) ◽  
pp. F100-F109 ◽  
Author(s):  
G. El Mernissi ◽  
D. Chabardes ◽  
A. Doucet ◽  
A. Hus-Citharel ◽  
M. Imbert-Teboul ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Atpase Activity ◽  
Protein Content ◽  
Basolateral Membrane ◽  
Chronic Administration ◽  
Distal Nephron ◽  
Nephron Segments ◽  
Collecting Tubule ◽  
Nephron Segment ◽  
Cortical Collecting Tubule

Chronic administration of DOCA to rabbits is known to increase the surface area of the basolateral membrane and the Na-K-ATPase activity of the cortical collecting tubule (CCT). We attempted to ascertain 1) whether Na-K-ATPase is the only basolateral membrane marker induced by DOCA, and 2) whether CCT is the only nephron segment affected by this steroid. We measured the activity of Na-K-ATPase and adenylate cyclase (AC) and the protein content of nephron segments microdissected from control and DOCA-treated rabbits. Morphogenic effects of DOCA, assessed by 30-60% increases in protein content, were specifically observed in the distal convoluted tubule, CCT, and medullary collecting tubule. When expressed as a function of tubular length, Na-K-ATPase activity rose from 80 to 200% in all these segments, whereas the increments in AC of 40-70%, observed in response to four different hormones, occurred only in some of them. When expressed as a function of protein content, Na-K-ATPase activity increased but AC activity remained unchanged. This study indicates that the morphogenic action resulting from chronic DOCA administration affects the entire rabbit distal nephron. During this action Na-K-ATPase is the preferentially induced enzyme.

Effect of adrenalectomy on NEM-sensitive ATPase along rat nephron and on urinary acidification

1987 ◽  
Vol 253 (3) ◽  
pp. F495-F499 ◽  
Author(s):  
C. Khadouri ◽  
S. Marsy ◽  
C. Barlet-Bas ◽  
A. Doucet
Keyword(s):  
Atpase Activity ◽  
Automatic Determination ◽  
Outer Medulla ◽  
Proton Secretion ◽  
Nephron Segments ◽  
Collecting Tubule ◽  
Single Nephron ◽  
Electrogenic Proton Pump ◽  
Adrenalectomized Rats

An N-ethyl-maleimide (NEM)-sensitive ATPase that displays the properties of an electrogenic proton pump has been described in the different segments of the rat nephron where it mediates part of the active tubular proton secretion. Because corticosteroids are known to control kidney acidification, we evaluated whether or not NEM-sensitive ATPase is a target of corticosteroids in some nephron segments. For this purpose we measured NEM-sensitive ATPase activity in the different segments of nephron microdissected from normal and adrenalectomized rats. Results indicate that within 1 wk after adrenalectomy NEM-sensitive ATPase activity was markedly decreased in both cortical and outer medullary portions of the collecting tubule (cortex, from 398 +/- 12 (+/-SE) to 145 +/- 20; outer medulla, from 293 +/- 21 to 112 +/- 14 pmol X mm-1 X h-1); however, it was not altered in any other segment of the nephron. These results demonstrate that kidney NEM-sensitive ATPase is under the control of corticosteroids and suggest that mineralocorticoids rather than glucocorticoids are involved in this regulation that specifically occurs in mineralocorticoid-sensitive nephron segments. This paper also describes a new computerized method for the automatic determination of the length of single nephron segments.

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