scholarly journals Inositol lipid signalling occurs in brush-border membranes during initiation of compensatory renal growth in the rat

1993 ◽  
Vol 295 (2) ◽  
pp. 599-605 ◽  
Author(s):  
H Banfić ◽  
M Vuica ◽  
M Knotek ◽  
S Moslavac ◽  
N Divecha
Keyword(s):  
Brush Border ◽  
Plasma Membranes ◽  
Rat Kidney ◽  
Unilateral Nephrectomy ◽  
Kidney Cortex ◽  
Compensatory Renal Growth ◽  
Rat Kidney Cortex ◽  
Contralateral Kidney ◽  
Inositol Lipids ◽  
Stimulation Of

Using highly specific mass assays, concentrations of inositol lipids and 1,2-diacylglycerol (DAG) were determined in plasma membranes isolated from rat kidney cortex. Significantly higher concentrations of inositol lipids were determined in brush-border (BBM) than in basal-lateral (BLM) plasma membranes, although DAG concentrations were similar in both. After unilateral nephrectomy, a decrease in PtdIns(4,5)P2 and PtdIns4P, with a concomitant increase in DAG and translocation of protein kinase C (PKC), were observed in BBM but not in BLM isolated from the remaining kidney. On the other hand, stimulation of renal cortical slices with insulin-like growth factor II (IGF-II) or phenylephrine caused similar effects in BLM but not in BBM. Stimulation of phospholipase C activity with translocation of PKC only to BBM in one kidney was also induced by occlusion of blood flow through the contralateral kidney for 15 min. At 30 min after the occlusion was removed and reflow established, DAG concentration and the amount of PKC in BBM returned to control values. These results suggest that an early signal after unilateral nephrectomy is transmitted to cells through BBM and can be switched on and off by blood occlusion and reflow through the contralateral kidney, while hormonal signals caused by IGF-II and phenylephrine are transmitted to cells through BLM.

scholarly journals Studies on the orientation of brush-border membrane vesicles

1978 ◽  
Vol 172 (1) ◽  
pp. 57-62 ◽  
Author(s):  
W Haase ◽  
A Schäfer ◽  
H Murer ◽  
R Kinne
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Kidney ◽  
Freeze Fracture ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Immunological Methods ◽  
Kidney Cortex ◽  
Asymmetric Distribution ◽  
Rat Kidney Cortex

Orientation of rat renal and intestinal brush-border membrane vesicles was studied with two independent methods: electron-microscopic freeze-fracture technique and immunological methods. With the freeze-fracture technique a distinct asymmetric distribution of particles on the two membrane fracture faces was demonstrated; this was used as a criterion for orientation of the isolated membrane vesicles. For the immunological approach the accessibility or inaccessibility of aminopeptidase M localized on the outer surface of the cell membrane to antibodies was used. With both methods we showed that the brush-border membrane vesicles isolated from rat kidney cortex and from rat small intestine for transport studies are predominantly orientated right-side out.

scholarly journals THE POLARITY OF THE PROXIMAL TUBULE CELL IN RAT KIDNEY

1972 ◽  
Vol 54 (2) ◽  
pp. 232-245 ◽  
Author(s):  
Hans-G Heidrich ◽  
Rolf Kinne ◽  
Eva Kinne-Saffran ◽  
Kurt Hannig
Keyword(s):  
Proximal Tubule ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Rat Kidney ◽  
High Specific Activity ◽  
Kidney Cortex ◽  
Proximal Tubule Cell ◽  
Surface Charges ◽  
Tubule Cell ◽  
Rat Kidney Cortex

Two different membrane fractions were obtained from a brush-border fraction of rat kidney cortex by using their different electrical surface charges in preparative free-flow electrophoresis. One membrane fraction contained only morphologically intact microvilli and was characterized by a high specific activity of alkaline phosphatase. The other fraction morphologically resembled classical plasma membranes by possessing junctional complexes and a high Na-K-ATPase activity The contamination of the isolated membrane fractions by other cell organelles was extremely low These two fractions represent the apical (luminal) and the basal (interstitial) area of the renal proximal tubule cell membrane and clearly demonstrate the polarity of this cell.

Tyrosine protein phosphorylation in plasma membranes of rat kidney cortex

1994 ◽  
Vol 267 (3) ◽  
pp. F415-F422
Author(s):  
L. Tremblay ◽  
R. Beliveau
Keyword(s):  
Protein Phosphorylation ◽  
Tyrosine Phosphorylation ◽  
Plasma Membranes ◽  
Rat Kidney ◽  
Specific Protein ◽  
Ammonium Molybdate ◽  
Kidney Cortex ◽  
Protein Kinase Activity ◽  
Rat Kidney Cortex ◽  
Endogenous Substrates

The endogenous tyrosine protein kinase activity (TPKA) associated with brush-border (BBM) and basolateral (BLM) membranes of rat kidney cortex was studied with an anti-phosphotyrosine monoclonal antibody (PY20). Distinct major phosphotyrosine-containing proteins were associated with BBM (50, 54, and 120 kDa) and BLM (37, 90, 130, and 170 kDa). For both plasma membranes, tyrosine phosphorylation leveled off after 10 min of incubation. Endogenous phosphotyrosine-specific protein phosphatases (PT-Pases) were active in both membranes, since the presence of sodium vanadate or ammonium molybdate, which are inhibitors of PTPases, was essential to detect endogenous phosphorylation. Substrates and/or tyrosine protein kinases (TPKs) seem to be differently distributed in these plasma membranes, since phosphorylation of endogenous substrates in BLM and BBM was differently sensitive to competitive inhibitors of TPKs. Moreover, insulin- and insulin-like growth factor I-stimulated tyrosine phosphorylation of a 90-kDa substrate was only observed in solubilized BLM proteins. However, similar p60v-src-related TPKs appear to be present in the BBM and BLM, since an antibody raised against p60v-src recognized proteins of 52, 58, and 75 kDa by immunoblotting and could immunoprecipitate the TPKs associated with both plasma membranes. These data provide evidence that the endogenous tyrosine protein phosphorylation observed in the BLM is catalyzed by nonreceptor TPKs as well as receptor TPKs, whereas that observed in the BBM is exclusively due to nonreceptor TPKs.

scholarly journals Phosphatidylinositol kinase and diphosphoinositide kinase of rat kidney cortex: properties and subcellular localization

1976 ◽  
Vol 160 (1) ◽  
pp. 97-105 ◽  
Author(s):  
P H Cooper ◽  
J N Hawthorne
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Brush Border ◽  
Rat Kidney ◽  
Subcellular Fractionation ◽  
Kidney Cortex ◽  
Marker Enzymes ◽  
Rat Kidney Cortex ◽  
Phosphatidylinositol Kinase ◽  
Golgi Membranes

The properties of phosphatidylinositol kinase and diphosphoinositide kinase from rat kidney cortex were studied. The enzymes were completely Mg2+-dependent. Cutscum detergent activated phosphatidylinositol kinase, but diphosphoinositide kinase was inhibited by all detergents tested. The pH optima were 7.7 for phosphatidylinositol kinase and 6.5 for diphosphoinositide kinase. On subcellular fractionation of kidney-cortex homogenates by differential centriflgation, the distribution of phosphatidylinositol kinase resembled that of the marker enzymes for brush-border, endoplasmic-reticulum and Golgi membranes. Diphosphoinositide kinase distribution resembled that of thiamin pyrophosphatase (assayed in the absence of ATP), diphosphoinositide phosphatase and triphosphoinositide phosphatase. Activities of both kinases were low in purified brush-border fragments. Diphosphoinositide kinase is probably localized in the Golgi complex.

Inhibition by phenylglyoxal of the sodium-coupled fluxes of glucose and phosphate in renal brush-border membranes

1988 ◽  
Vol 66 (9) ◽  
pp. 1005-1012 ◽  
Author(s):  
R. Béliveau ◽  
M. Bernier ◽  
S. Giroux ◽  
D. Bates
Keyword(s):  
Brush Border ◽  
Direct Method ◽  
Rat Kidney ◽  
Membrane Vesicles ◽  
Kidney Cortex ◽  
Sodium Influx ◽  
Rat Kidney Cortex ◽  
Process Modification ◽  
Arginine Residues ◽  
Phosphate Influx

The coupling of phosphate and glucose transport to sodium in brush-border membrane vesicles from rat kidney cortex was studied after chemical modification of arginine residues by phenylglyoxal. Phosphate (10 mM) and sodium (20 mM) uptakes were linear for 6 s and stimulated in the presence of their cosubstrate. The sodium: phosphate stoichiometry measured by a direct method was 1.74. Sodium-independent phosphate and glucose influx were found to be unaffected by phenylglyoxylation. Phosphate- or glucose-independent sodium influx also remained unaltered by the treatment. However, phosphate influx measured with sodium was inhibited by 69% and sodium influx measured with phosphate was inhibited by 40%. When these values were corrected for uncoupled fluxes, the sodium influx coupled to phosphate and the phosphate influx coupled to sodium were inhibited by 93 and 95%, respectively. Glucose influx measured in the presence of sodium was inhibited by 36% and sodium influx in the presence of glucose was reduced by 39%. When the values were corrected for diffusion, these inhibitions were 95 and 100%, respectively. We conclude that the coupling of phosphate and glucose to sodium fluxes by the renal carriers requires the participation of arginine residue(s) in the translocation process. Modification of this arginine by phenylglyoxal leads to a marked inhibition of coupling. These results suggest the implication of arginine residues in the molecular coupling for both glucose and phosphate sodium symporters.

Kinetic model for phosphate transport in renal brush-border membranes

1988 ◽  
Vol 254 (3) ◽  
pp. F329-F336 ◽  
Author(s):  
R. Beliveau ◽  
J. Strevey
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Membrane Vesicles ◽  
Phosphate Transport ◽  
Kidney Cortex ◽  
Binary Complex ◽  
Rat Kidney Cortex ◽  
First Time ◽  
Phosphate Influx ◽  
Phosphate Carrier

Phosphate transport was studied in brush-border membrane vesicles purified from rat kidney cortex. Influx and efflux were strongly dependent on the presence of cis sodium; the rate of efflux, calculated by linear regression performed on the first time points, was much lower than the rate of influx (0.044 vs. 0.198 pmol.microgram protein-1.s-1). Trans phosphate had a stimulatory effect on phosphate influx (145% stimulation at 10 mM phosphate trans, with 0.2 mM phosphate cis). Trans phosphate was, however, inhibitory for phosphate efflux (89% inhibition at 10 mM phosphate trans). Trans effects of sodium were also studied. With 200 mM trans sodium, we observed 73% inhibition of phosphate influx and 60% inhibition of phosphate efflux. Studies involving sodium and phosphate present at the same time as trans substrates showed that the trans inhibition of phosphate influx by sodium could be completely reversed by trans phosphate. Trans inhibition of phosphate efflux by phosphate was not additive to the inhibition caused by sodium. Addition of trans phosphate had a stimulatory effect on sodium-independent influx, indicating that the binary complex (C-P) could translocate in efflux. These results indicate that the renal phosphate carrier presents a random binding scheme for the intra- and extravesicular sides of the membrane.

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