Dopamine production by isolated glomeruli and tubules from rat kidneys

1985 ◽  
Vol 63 (2) ◽  
pp. 155-158 ◽  
Author(s):  
A. D. Baines ◽  
R. Drangova ◽  
C. Hatcher
Keyword(s):  
Alkaline Phosphatase ◽  
Proximal Tubule ◽  
Renal Cortex ◽  
Proximal Tubules ◽  
Renal Nerves ◽  
Isolated Glomeruli ◽  
Norepinephrine Content ◽  
Wet Weight ◽  
Distal Tubules ◽  
Layer I

To locate the sites of dopamine (D) production in rat renal cortex, we separated glomeruli and proximal tubules by sieving or centrifugation in Percoll after collagenase digestion. After centrifugation layer I contained 60–80% glomeruli and 20–40% tubule fragments, half of which did not stain with alkaline phosphatase, layer II contained 0–5% glomeruli, 10–25% tubule fragments other than proximal tubules, and 70–85% proximal tubule fragments. Layer IV contained 85–95% proximal tubules. Gluconeogenic rates were (micromoles per hour per gram wet weight) as follows: I, 4 ± 1; II, 7 ± 2; and IV, 16 ± 1. Norepinephrine (NE) content was (picomoles per gram wet weight) I, 310 ± 30; II, 540 ± 40; IV, 195 ± 60. D content was (picomoles per gram wet weight) I, 26 ± 6; II, 46 ± 13; IV, 33 ± 7. Surgical denervation 4–6 days previously reduced the norepinephrine content of layers I and II to 35 ± 10 (p < 0.001) and of IV to 60 ± 20 (p < 0.05) and the D content of layers I and II to 13 ± 6 and 6 ± 6 pmol/g, respectively (p < 0.01); D content of layer IV was unchanged. D production from 10−7 M 3,4-dihydroxyphenylalanine (DOPA) was (nanomoles per gram per minute) I, 0.2 ± 0.03; II, 0.7 ± 0.1; IV, 1.0 ± 0.04. DOPA consumption was (nanomoles per gram per minute) I, 0.6 ± 0.1; II, 1.4 ± 0.3; and IV, 1.8 ± 0.2. Denervation did not change D production or DOPA consumption. Glomeruli without arterioles or tubules, obtained by sieving, contained no D or NE and did not produce D from DOPA. We conclude that proximal tubules produced at least five times more D from DOPA than glomeruli and distal tubules. Renal nerves did not contribute significantly to D production. We found no evidence of specific D-containing nerves associated with rat glomeruli.

scholarly journals Endopeptidases (kininases) are able to hydrolyze kinins in tubular fluid along the rat nephron

1999 ◽  
Vol 277 (1) ◽  
pp. F66-F74 ◽  
Author(s):  
D. E. Casarini ◽  
M. A. Boim ◽  
R. C. R. Stella ◽  
N. Schor
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Proximal Tubule ◽  
Physiological Role ◽  
Distal Tubule ◽  
Neutral Endopeptidase ◽  
Prolyl Endopeptidase ◽  
Proximal Tubules ◽  
Converting Enzyme ◽  
Distal Nephron ◽  
Distal Tubules

The activities of serine endopeptidase, prolyl endopeptidase and neutral endopeptidase were determined in tubular fluid collected from several portions of the rat nephron as well as in urine. The enzyme activities were measured by HPLC using bradykinin (BK) as substrate. Free residual peptides of BK obtained by the action of these enzymes on the locally produced BK were also determined. The endopeptidase activities were found to be present throughout the nephron. Equimolar fragments of BK were detected in the early proximal tubule (Arg1-Pro7, Phe8-Arg9, Arg1-Gly4, Phe5-Arg9, and BK), late proximal tubule (Arg1-Phe5, Arg1-Pro7, Gly4-Pro7, Gly4-Arg9, and BK), late distal tubule (Arg1-Gly4, Phe5-Arg9, Arg1-Phe5, Ser6-Arg9, Gly4-Arg9, BK, and [des-Arg9]BK) and urine (Phe8-Arg9, Phe5-Arg9, Arg1-Phe5, Ser6-Arg9, Arg1-Pro7, Gly4-Pro7, Gly4-Arg9, BK, and [des-Arg9]BK). Our data suggest that the endopeptidases and exopeptidases are secreted by the nephron. Early proximal tubules secrete angiotensin converting enzyme and neutral endopeptidase, differing from late distal tubules that produce prolyl endopeptidase, serine endopeptidase, carboxypeptidase, and also neutral endopeptidase. All enzymes detected along the rat nephron were found in the urine. The existence of endopeptidases and carboxypeptidase in the distal nephron may have a potential physiological role in the inactivation of the kinins formed by kallikrein in the kidney and also in the inactivation of additional peptides other than BK.

scholarly journals Transport ATPase cytochemistry: ultrastructural localization of potassium-dependent and potassium-independent phosphatase activities in rat kidney cortex.

1975 ◽  
Vol 66 (3) ◽  
pp. 586-608 ◽  
Author(s):  
S A Ernst
Keyword(s):  
Alkaline Phosphatase ◽  
Atpase Activity ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Distal Tubules ◽  
Extracellular Side ◽  
Collecting Tubules

A cytochemical method for the light and electron microscope localization of the K- and Mg-dependent phosphatase component of the Na-K-ATPase complex was applied to rat kidney cortex, utilizing p-nitrophenylphosphate (NPP) as substrate. Localization of K-N-ATPase activity in kidneys fixed by perfusion with 1% paraformaldehyde -0.25% glutaraldehyde demonstrated that distal tubules are the major cortical site for this sodium transport enzyme. Cortical collecting tubules were moderately reactive, whereas activity in proximal tubules was resolved only after short fixation times and long incubations. In all cases, K-NPPase activity was restricted to the cytoplasmic side of the basolateral plasma membranes, which are characterized in these neplron segments by elaborate folding of the cell surface. Although the rat K-NPPase appeared almost completely insensitive to ouabain with this cytochemical medium, parallel studies with the more glycoside-sensitive rabbit kidney indicated that K-NPPase activity in these nephron segments is sensitive to this inhibitor. In addition to K-NPPase, nonspecific alkaline phosphatase also hydrolyzed NPP. The latter could be differentiated cytochemically from the specific phosphatase, since alkaline phosphatase was K-independent, insensitive to ouabain, and specifically inhibited by cysteine. Unlike K-NPPPase, alkaline phosphatase was localized primarily to the extracellular side of the microvillar border of proximal tubules. A small amount of cysteine-sensitive activity was resolved along peritubular surfaces of proximal tubules. Distal tubules were unreactive. In comparative studies, Mg-ATPase activity was localized along the extracellular side of the luminal and basolateral surfaces of proximal and distal tubules and the basolateral membranes of collecting tubules.

scholarly journals Phosphophloretin sensitivity of rabbit renal NaPi-IIa and NaPi-Ia

2004 ◽  
Vol 286 (5) ◽  
pp. F955-F964 ◽  
Author(s):  
Brian E. Peerce ◽  
Brandon Peerce ◽  
Rebecca D. Clarke
Keyword(s):  
Renal Cortex ◽  
Phosphate Uptake ◽  
Ph Dependence ◽  
Membrane Vesicles ◽  
Distal Tubule ◽  
Proximal Tubules ◽  
Dependent Manner ◽  
Renal Brush Border Membrane ◽  
Distal Tubules ◽  
Dose Dependent

The effect of phosphorylated phloretins on Na+-dependent phosphate uptake into rabbit renal brush-border membrane vesicles (BBMV) was examined. Na+-dependent phosphate uptake into isolated rabbit cortex BBMV was sensitive to 2′-phosphophloretin (2′-PP) and 2′-phospho-4′,4,6′-trimethoxy phloretin (PTMP) in a dose-dependent and pH-dependent manner. PTMP inhibition of Na+-dependent phosphate uptake was maximum at alkali pH, and 2′-PP inhibition of Na+-dependent phosphate uptake was maximum at acidic pH. Increasing Na+ concentrations did not increase PTMP inhibition of renal cortex BBMV Na+-dependent phosphate uptake at pH 6. The effect of phosphophloretins on Na+-dependent phosphate uptake was examined in BBMV isolated from purified proximal tubules and distal tubules. 2′-PP and PTMP inhibition of Na+-dependent phosphate uptake into BBMV isolated from purified proximal tubules was similar to the inhibition seen with BBMV from renal cortex. 2′-PP, but not PTMP, inhibited Na+-dependent phosphate uptake into BBMV isolated from purified distal tubules. The pH dependence of inhibition, the absence of PTMP inhibition of Na+-dependent phosphate uptake into distal tubule BBMV, and the inhibition of Na+-dependent phosphate uptake into distal tubule BBMV suggest that NaPi-Ia is 2′-PP sensitive and NaPi-IIa is PTMP sensitive.

scholarly journals Effect of Hypodynamy on Structure and Alkaline Phosphatase Activity of Kidney in Japanese Quails

2008 ◽  
Vol 77 (3) ◽  
pp. 313-320 ◽  
Author(s):  
V. Almášiová ◽  
V. Cigánková ◽  
K. Holovská ◽  
Ľ. Lenhardt ◽  
P. Škrobánek ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Japanese Quail ◽  
Alkaline Phosphatase Activity ◽  
Proximal Tubules ◽  
Experimental Animals ◽  
Japanese Quails ◽  
Negative Effect ◽  
Distal Tubules ◽  
Dying Cells

The objective of the study was to observe the effect of experimental hypodynamy simulating weightlessness in space on the structure, ultrastructure and alkaline phosphatase activity of kidney in Japanese quail (Coturnix coturnix japonica). Two days after hatching, the quails were suspended in special shirts below the cage ceiling so their feet did not touch the floor. They could consume food and water ad libitum. Experimental animals were sacrificed after 14, 21, 28, 35, 42, 49 and 56 days of hypodynamy. Birds of the same age, hatched at the same time, and fed the same diet were used as a control. Samples of kidney were processed for light (LM) and transmission electron microscopy (TEM), and alkaline phosphatase (AP) analysis. Short-term (14–28 days) hypodynamy caused no marked damage to the structure and ultrastructure of kidneys. However, after long-term (35–59 days) hypodynamy, morphological changes were observed in some cells of the proximal and distal tubules. The dying cells in proximal tubules, observed in semi-thin sections by LM, were dark and contained a nucleus of irregular shape. Observation by TEM showed that their nucleus was dark and shrivelled and the electron-dense cytoplasm contained long, dense, rod-shaped mitochondria with thin mitochondrial cristae. Microvilli were present on the apical surface of cells and formed a brush border. Sporadic dying cells were also observed in distal tubules. Large, light vacuoles were found in the cytoplasm of cells of collecting tubules, however, the structure of renal corpuscles and medullary loops remained undisturbed. Microscopical analysis by means of a direct TUNEL reaction on days 35 to 59 of hypodynamy showed a moderate occurrence of cellular apoptosis in the proximal and distal tubules of experimental Japanese quail. The activity of AP in the brush border of the proximal tubules on days 14–29 of hypodynamy was normal in experimental animals and showed no significant differences in comparison with the control. Between days 35 and 59 of hypodynamy a moderate decrease in the content of AP in experimental animals in comparison with the control (P < 0.01) was observed. Our results indicated that long-term hypodynamy caused apoptosis of some cells in the proximal and distal tubules and therefore had a negative effect on the kidney structure. The occurrence of apoptosis was only sporadic. We presume no negative effect on the kidney function and the Japanese quails are capable of further development under the conditions of prolonged simulated weightlessness.

Kidneys sans glomeruli

2004 ◽  
Vol 286 (5) ◽  
pp. F811-F827 ◽  
Author(s):  
Klaus W. Beyenbach
Keyword(s):  
Proximal Tubule ◽  
Glomerular Filtration ◽  
Water Flow ◽  
Tubular Secretion ◽  
Proximal Tubules ◽  
Renal Tubules ◽  
Cl Secretion ◽  
Distal Tubules ◽  
Urine Formation ◽  
Water Secretion

The evolution of the vertebrate kidney records three occasions, each separated by about 50 million years, when fish have abandoned glomeruli to produce urine by tubular mechanisms. The recurring dismissal of glomeruli suggests a mechanism of aglomerular urine formation intrinsic to renal tubules. Indeed, the transepithelial secretion of organic solutes and of inorganic solutes such as sulfate, phosphate, and magnesium can all drive secretory water flow in renal proximal tubules of fish. However, the secretion of NaCl via secondary active transport of Cl is the primary mover of secretory water flow in, surprisingly, proximal tubules of both glomerular and aglomerular fish. In filtering kidneys, the tubular secretion of solute and water is overshadowed by reabsorptive transport activities, but secretion progressively comes to light as glomerular filtration decreases. Thus the difference between glomerular and aglomerular urine formation is more a difference of degree than of kind. At low rates of glomerular filtration in seawater fish, NaCl-coupled water secretion serves to increase the renal excretory capacity by increasing the luminal volume into which waste, excess, and toxic solutes can be secreted. The reabsorption of NaCl and water in the distal nephron and urinary bladder concentrates unwanted solutes for excretion while minimizing renal water loss. In aglomerular fish, NaCl-coupled water secretion across proximal tubules replaces glomerular filtration to increase renal excretory capacity. A review of the literature suggests that tubular secretion of NaCl and water is an early function of the vertebrate proximal tubule that has been retained throughout evolution. Active transepithelial Cl secretion takes place in gall bladders studied as models of the mammalian proximal tubule and in proximal tubules of amphibians and apparently also of mammals. The tubular secretion of Cl is also observed in mammalian distal tubules. The evidence consistent with and for Cl secretion in, respectively, proximal and distal tubules of the mammalian kidney calls for a reexamination of basic assumptions in renal physiology that may lead to new opportunities for managing some forms of renal disease.

THE EFFECT OF DAMAGE TO VARIOUS PARTS OF THE RENAL TUBULE ON THE EXCRETION OF PHOSPHATE BY THE DOG'S KIDNEY

1959 ◽  
Vol 37 (1) ◽  
pp. 103-111 ◽  
Author(s):  
T. F. Nicholson ◽  
G. W. Shepherd
Keyword(s):  
Proximal Tubule ◽  
Mercuric Chloride ◽  
Renal Tubule ◽  
Potassium Dichromate ◽  
Left Kidney ◽  
Distal Tubule ◽  
Proximal Tubules ◽  
Sodium Tartrate ◽  
Phosphate Excretion ◽  
Distal Tubules

The first third of the proximal tubules of the left kidney in dogs was damaged by the injection of 2.5 mg% potassium dichromate, the last two thirds by the injection of 0.5% sodium tartrate, and the distal tubules by the retrograde injection up the ureter of 0.05% mercuric chloride. Damage to the first third of the proximal tubule resulted in marked increase in phosphate excretion. Damage to the last two thirds of the proximal tubule had no significant effect on the output of phosphate. When the distal tubule was damaged the excretion of phosphate was greatly reduced. The results indicate that phosphate is reabsorbed in the first third of the proximal tubule and actively excreted by the distal tubule.

THE EFFECT OF DAMAGE TO VARIOUS PARTS OF THE RENAL TUBULE ON THE EXCRETION OF PHOSPHATE BY THE DOG'S KIDNEY

1959 ◽  
Vol 37 (1) ◽  
pp. 103-111 ◽  
Author(s):  
T. F. Nicholson ◽  
G. W. Shepherd
Keyword(s):  
Proximal Tubule ◽  
Mercuric Chloride ◽  
Renal Tubule ◽  
Potassium Dichromate ◽  
Left Kidney ◽  
Distal Tubule ◽  
Proximal Tubules ◽  
Sodium Tartrate ◽  
Phosphate Excretion ◽  
Distal Tubules

The first third of the proximal tubules of the left kidney in dogs was damaged by the injection of 2.5 mg% potassium dichromate, the last two thirds by the injection of 0.5% sodium tartrate, and the distal tubules by the retrograde injection up the ureter of 0.05% mercuric chloride. Damage to the first third of the proximal tubule resulted in marked increase in phosphate excretion. Damage to the last two thirds of the proximal tubule had no significant effect on the output of phosphate. When the distal tubule was damaged the excretion of phosphate was greatly reduced. The results indicate that phosphate is reabsorbed in the first third of the proximal tubule and actively excreted by the distal tubule.

Mechanism of glucocorticoid effect on renal transport of phosphate

1982 ◽  
Vol 243 (5) ◽  
pp. C227-C236 ◽  
Author(s):  
S. T. Turner ◽  
G. M. Kiebzak ◽  
T. P. Dousa
Keyword(s):  
Alkaline Phosphatase ◽  
Renal Cortex ◽  
Specific Activity ◽  
Maximum Velocity ◽  
Metabolic Changes ◽  
Proximal Tubules ◽  
Time Interval ◽  
Gamma Glutamyl Transferase ◽  
Glutamyl Transferase

We explored whether glucocorticoid administration, a known stimulus of renal gluconeogenesis (GNG), could decrease avid inorganic phosphate (Pi) reabsorption in rats stabilized on low-phosphorus diet (LPD). Rats adapted to LPD were injected with the glucocorticoid (GCD) triamcinolone acetonide (1.25 or 2.5 mg.100 g body wt-1.day-1 ip) for 2 days; they showed a profound increase in urinary excretion of Pi during the injection period. In clearance studies GCD increased the clearance and fractional excretion of Pi but did not change the filtered load of Pi. Initial "uphill" Na+-gradient (Nao+ greater than Nai+)-dependent uptake of 32Pi by luminal brush-border membrane (BBM) vesicles prepared from renal cortex of rats treated with GCD was markedly (greater than 40%) decreased compared with control rats; Na+-gradient-dependent uptake of D-[3H]glucose was not diminished. At the "equilibrium" time interval, measured at 120 min, BBM vesicles from control and GCD-treated rats did not differ in the uptake of 32Pi or D-[3H]glucose. With kinetic analysis, BBM from GCD-treated rats showed a marked decrease (-40%) in the maximum velocity (Vmax) of initial Na+-dependent 32Pi uptake, but the apparent affinity of the BBM transport system for Pi (apparent Km = 0.078 mM Pi) was not different from that of controls. Alkaline phosphatase specific activity was much lower (-40%) in BBM from GCD-treated rats compared with controls, but the activities of three other BBM enzymes (maltase, leucine aminopeptidase, and gamma-glutamyl transferase) were not different. The addition of triamcinolone to BBM in vitro had no effect on either Na+-dependent uptake of 32Pi or alkaline phosphatase activity. The rate of GNG from alpha-ketoglutarate was significantly increased in cortical slices from GCD-treated rats adapted to LPD. Also, the NAD+-to-NADH ratio was higher in the renal cortex of GCD-treated rats, although the total content of NAD [NAD+ + NADH] was not different from controls. Renal excretory, BBM, and metabolic changes elicited controls. Renal excretory, BBM, and metabolic changes elicited by GCD treatment were similar in intact and thyroparathyroidectomized rats. Phosphaturia elicited in rats fed LPD by GCD administration in vivo appears to be at least in part due to a decreased capacity of luminal BBM of proximal tubules for decreased capacity of luminal BBM of proximal tubules for Na+-dependent uptake of Pi. Although the causal relationship between observed parameters is not established, our results are compatible with the interpretation that an increase in the rate of renal GNG, perhaps via action of NAD+ on BBM (J. Clin. Invest. 67: 1347-1360, 1981), decreases luminal uptake and reabsorption of Pi in proximal tubules.

scholarly journals High Salt Intake–Increased (Pro)renin Receptor Expression Is Exaggerated in the Kidney of Dahl Salt-Sensitive Rats

Hypertension ◽  
2020 ◽  
Vol 75 (6) ◽  
pp. 1447-1454
Author(s):  
Seiko Yamakoshi ◽  
Osamu Ito ◽  
Rong Rong ◽  
Yusuke Ohsaki ◽  
Takahiro Nakamura ◽  
...  
Keyword(s):  
Renal Cortex ◽  
Salt Intake ◽  
High Salt ◽  
Proximal Tubules ◽  
Receptor Expression ◽  
Dependent Manner ◽  
Mineralocorticoid Receptor Antagonist ◽  
Salt Diet ◽  
High Salt Intake ◽  
Distal Tubules

The (P)RR ([pro]renin receptor) was identified as a new component of the renin-angiotensin system. We previously reported that high salt (HS) intake increased the (P)RR expression in several nephron segments of Sprague-Dawley rats. Other studies reported HS intake increased the XO (xanthine oxidase) activity and an MR (mineralocorticoid receptor) antagonist inhibited HS intake–increased (P)RR expression in the kidneys of Dahl salt-sensitive (DS) rats. The present study examined the effects of HS intake on (P)RR expression in the kidney of DS rats. Male DS rats were fed a normal salt diet or an HS diet for 4 weeks. Some of the rats fed on the HS diet were treated with the XO inhibitor, febuxostat, and the MR antagonist, spironolactone. Immunoblot and immunohistochemical analyses showed that HS intake increased (P)RR expression in the renal cortex by 22.6-fold, the proximal tubules by 4.9-fold and the distal tubules, respectively. Both febuxostat and spironolactone inhibited HS intake–increased (P)RR expression in the renal cortex. Febuxostat inhibited HS intake–increased (P)RR expression in the proximal tubules, whereas spironolactone inhibited HS intake–increased (P)RR expression in the distal tubules. Additionally, deoxycorticosterone acetate increased (P)RR expression in the renal cortex and distal tubules but not in the proximal tubules of DS rats fed the normal salt diet. These results indicate that HS intake greatly increases (P)RR expression in the renal cortex of DS rats. The mechanisms of HS intake–increased (P)RR expression may work in an XO-dependent manner in the proximal tubules and an MR-dependent manner in the distal tubules.

Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

1985 ◽  
Vol 43 ◽  
pp. 474-475
Author(s):  
A. LeFurgey ◽  
P. Ingram ◽  
L.J. Mandel
Keyword(s):  
Smooth Muscle ◽  
Proximal Tubule ◽  
Electron Probe ◽  
Clinical Applications ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Target Cells ◽  
X Ray ◽  
Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

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