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B C Kone

Publications and source records attributed to B C Kone.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of chronic hypokalemia on renal expression of the "gastric" H(+)-K(+)-ATPase alpha-subunit gene.

Chronic potassium restriction leads to active potassium reabsorption in the late distal nephron and collecting duct, segments known to express "gastric" H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) alpha-subunit mRNA. In this study, the cellular distribution and relative abundance of mRNA encoding this isoform were examined in kidneys of normal and potassium-deprived (2 wk) rats. In situ hybridization with isoform-specific cRNA probes demonstrated prominent expression of this gene in the connecting segment (CNT), entire collecting duct, and renal papillary surface epithelium in a comparable distribution in both groups of rats. Hypertrophy of the outer medullary collecting ducts in the inner stripe of potassium-restricted rats was observed. Competitive polymerase chain reaction analysis revealed twofold greater levels of gastric H(+)-K(+)-ATPase alpha-subunit mRNA (normalized to the level of beta-actin mRNA) in the cortex, but roughly comparable levels in the outer and inner medulla, of potassium-restricted rats compared with controls. These data suggest that chronic potassium restriction results in modestly enhanced renal cortical expression of the gastric H(+)-K(+)-ATPase alpha-subunit gene and that this isoform may participate in potassium conversation by the CNT and cortical collecting duct during potassium deprivation.

Animals↗
PubMed1996

Chronic hypokalemia enhances expression of the H(+)-K(+)-ATPase alpha 2-subunit gene in renal medulla.

Recent molecular and physiological studies suggested that at least two H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) isozymes are expressed in the rat kidney and that these ion pumps respond to changes in dietary potassium balance. We used Northern analysis and in situ hybridization to analyze the expression of mRNA encoding the "colonic" isoform of the H(+)-K(+)-ATPase alpha-subunit (HK alpha 2) in normal and potassium-deprived (2 wk) rats. Control rats exhibited low levels of HK alpha 2 mRNA in the cortical and medullary thick ascending limb, distal convoluted tubule, connecting segment, and the entire collecting duct. The potassium-deprived rats expressed approximately fivefold higher levels of HK alpha 2 mRNA in the outer and inner medulla compared with controls, as well as hypertrophy and increased in situ hybridization signal in the intercalated cells of the inner stripe of the outer medullary collecting duct and the proximal inner medullary collecting duct. In contrast, renal cortical expression of HK alpha 2 mRNA was low and comparable in the two groups. Our results suggest that enhanced expression of the HK alpha 2 subunit gene in the renal medulla contributes to potassium conservation during chronic hypokalemia.

Animals↗
PubMed1996

Renal H,K-ATPase: structure, function and regulation.

The H,K-ATPase comprises a family of isoenzymes with unique biochemical, pharmacological, and regulatory properties. This review explores recent advances in discovery of the molecular biology, biochemistry, and function of these ion pumps, with particular emphasis on the implications for renal potassium and proton handling. Structure-function correlations governing the ion transport mechanisms, inhibitor binding sites, oligomerization, and transcriptional control of the H,K-ATPase isoforms are examined. Functional studies of H,K-ATPase in renal tubules and cultured epithelial cells are analyzed and related to data concerning the expression and distribution of the H,K-ATPase gene products in the kidney. Functional and molecular biological evidence for adaptive changes in renal H,K-ATPase expression during the evolution of potassium and acid-base disturbances are discussed. Current investigative challenges and avenues for future research of these enzymes are presented.

Acid-Base Imbalance↗
PubMed1996

Macrophages and chronic renal allograft nephropathy.

In a previous study we demonstrated that macrophage infiltrates stained for thromboxane A synthase (TxAS) correlated inversely with renal function six months after biopsy. We propose that macrophage based inflammation is a cofactor leading to chronic allograft nephropathy. For this study we compared four indices of renal allograft nephropathy with renal survival. The Banff Score of Inflammatory Changes (BSI) is an index of acute inflammation. The Banff Chronic Index (BCI) and Chronic Allograft Damage Index (CADI) are indexes of chronic disease. The Macrophage Index (MI) is the same as the BSI applied only to macrophages. These indices were determined on renal allograft biopsies obtained because of delayed graft function within the first week of transplantation, and for increasing plasma creatinine levels after stable function. All four indices predicted renal survival in the post-biopsy interval. MI predicted renal survival for the entire transplant period. In addition, the presence of TxAS transcripts in the renal allografts was determined using a reverse transcription-polymerase chain reaction-based assay. This confirms previous observations of TxAS in the grafts. This study supports the hypothesis that macrophage derived inflammation is a cofactor for chronic allograft nephropathy.

Biopsy↗
PubMed1995

Expression and cellular localization of mRNA encoding the "gastric" isoform of H(+)-K(+)-ATPase alpha-subunit in rat kidney.

The distribution of transcripts encoding the gastric H(+)-K(+)-adenosinetriphosphatase (ATPase) alpha-subunit in the normal rat kidney was studied by reverse transcription-polymerase chain reaction (RT-PCR), combined with DNA sequence analysis and renal microdissection, and by nonradioactive in situ hybridization of fixed kidney sections using highly specific molecular probes. RT-PCR products corresponding to the gastric H(+)-K(+)-ATPase alpha-subunit were detected in the cortex, outer and inner medulla, and in isolated cortical (CCD) and inner medullary collecting ducts (IMCD). With digoxigenin-labeled cRNAs derived from the 5' and 3' ends of the gastric H(+)-K(+)-ATPase alpha-subunit cDNA, specific hybridization signal was detected prominently in all the cells of the connecting segment and CCD, the intercalated cells of the outer medullary collecting duct, the IMCD, and the renal pelvic epithelium lining the secondary pouches. Weak labeling was noted in the S3 segment of the proximal tubule, the distal convoluted tubule, and the cortical thick ascending limb of Henle. Hybridization with the sense probes produced no cellular labeling. These data provide the first direct demonstration for the expression and cellular distribution of mRNA encoding the gastric H(+)-K(+)-ATPase alpha-subunit in the normal, potassium-replete kidney, and they provide essential tools for the molecular analysis of renal acid base and potassium transport under physiological and pathophysiological conditions.

Animals↗
PubMed1995

Cytokines activate inducible nitric oxide synthase gene transcription in inner medullary collecting duct cells.

The effects of lipopolysaccharide (LPS) and/or inflammatory cytokines on the expression of inducible nitric oxide synthase (iNOS) were studied in mIMCD-3 cells, derived from the murine inner medullary collecting duct. Under basal conditions, the production of nitrite, a stable metabolite of NO, was negligible; however, incubation with tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IF-gamma) for 24 h resulted in a 12-fold increase in nitrite synthesis and the appearance of abundant iNOS mRNA and protein. The induction of nitrite production and iNOS mRNA was time dependent, requiring approximately 8 h for expression of significant levels of nitrite or iNOS mRNA. Coincubation with the transcription inhibitor actinomycin D or the translation inhibitor cycloheximide prevented the cytokine induction of iNOS mRNA and NO production, indicating that synthesis of intermediary proteins stimulated transcription of the iNOS gene. Nuclear run-on transcription demonstrated that the iNOS gene was transcriptionally inactive under basal conditions, but was markedly induced by TNF-alpha and IF-gamma. These results indicate that inflammatory cytokines stimulate NO production in mIMCD-3 cells by activating iNOS gene transcription in a process that requires new protein synthesis.

Amino Acid Oxidoreductases↗
PubMed1995

Role of NF-kappa B in the regulation of inducible nitric oxide synthase in an MTAL cell line.

The effects of cytokines, lipopolysaccharide (LPS), 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), and pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappa B) activation, on inducible nitric oxide synthase (iNOS) expression were studied in the medullary thick ascending limb of Henle's loop cell line ST-1. LPS + interferon-gamma (IF-gamma) promoted a time-dependent increase in nitrite (a NO metabolite) and iNOS mRNA and the appearance of NF-kappa B p50 and p65 in nuclear protein extracts. Actinomycin D but not cycloheximide prevented the LPS + IF-gamma induction of iNOS mRNA and NO synthesis, indicating that iNOS transcriptional activation by LPS + IF-gamma does not require newly synthesized proteins. PDTC inhibited the LPS + IF-gamma induction of NO, iNOS mRNA, and the appearance of NF-kappa B in nuclear protein extracts, suggesting that NF-kappa B mobilization and trans-activation of the iNOS gene mediates this induction. In contrast to other cell types, cycloheximide did not alter iNOS mRNA stability, and 8-BrcAMP did not alter basal or LPS+IF-gamma induced NO production in ST-1 cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Identification of constitutive and inducible forms of nitric oxide synthase in human platelets.

A number of cell types possess an L-arginine-nitric oxide (NO) pathway. We studied the presence of constitutive and inducible forms of NO synthase in human platelets. N omega-nitro-L-arginine, an inhibitor of NO synthase, potentiated thrombin-induced aggregation of washed human platelets, whereas L-arginine inhibited it. The direct evidence for the presence of constitutive form of NO synthase came from the observation of conversion of tritium-labeled L-arginine to tritium-labeled L-citrulline by washed platelets suspended in Ca(++)-rich but not in Ca(++)-free buffer. Incubation of washed platelets in Ca(++)-free buffer with cytokines (tumor necrosis factor-alpha and interferon-gamma) or cytokines plus lipopolysaccharide caused a marked increase in the conversion of [3H]L-arginine to [3H]L-citrulline, suggesting the presence of inducible form of NO synthase. Gel electrophoresis identified an approximately 130 kd protein band with NO synthase in the platelet cytosol, which on isolation converted [3H]L-arginine to [3H]L-citrulline. This 130 kd protein required the presence of Ca++, reduced nicotinamide adenine dinucleotide phosphate tetrahydro-L-biopterin, and flavin adenine dinucleotide for expression of NO synthase activity. Platelet sonicates demonstrated presence of nitrite, and its concentrations were lowered by preincubation of platelets with NG-nitro-L-arginine methyl ester and enhanced in cytokine-treated platelets. Reverse-transcription polymerase chain reaction demonstrated messenger RNA expression of the constitutive endothelial (but not brain) and inducible isoforms of NO synthase in platelets. These observations indicate that human platelet cytosol possesses both constitutive and inducible forms of NO synthase.

Amino Acid Oxidoreductases↗
PubMed1994

Segmental localization of mRNAs encoding Na(+)-K(+)-ATPase alpha- and beta-subunit isoforms in rat kidney using RT-PCR.

To characterize the expression of genes encoding the alpha- and beta-subunit isoforms of the Na(+)-K(+)-ATPase in rat kidney, we used reverse transcription (RT)-PCR of microdissected renal structures combined with quantitation of subunit isoform mRNAs in the major renal parenchymal zones. Transcripts for alpha 1, alpha 2, alpha 3, beta 1, and beta 2 subunit isoforms were detected by RT-PCR in microdissected glomeruli, proximal convoluted tubules, medullary thick ascending limbs of Henle, cortical and inner medullary collecting ducts. The truncated alpha 1 (alpha 1-T) isoform was also amplified from cortex, outer and inner medulla and isolated glomeruli, but it was not detected in these nephron segments. The DNA sequence of the renal alpha 1-T PCR product was identical to that of the cDNA previously cloned from aortic smooth muscle cells. RNA dot-blot analysis indicated that the alpha 1, alpha 2, and alpha 3 isoforms contributed approximately 70%, approximately 20%, and approximately 10%, respectively, of the total alpha isoform mRNA in each parenchymal zone. RNase protection assays determined that the beta 1 and beta 2 isoforms accounted for approximately 95% and approximately 5%, respectively, of the beta isoform mRNA in each zone. These data provide definitive evidence for the differential expression of mRNAs encoding all the alpha and beta isoforms in the renal parenchyma, and for the coexpression of these isoforms in the nephron segments examined. The results suggest the potential expression of up to eight different Na(+)-K(+)-ATPase isoenzymes in the kidney, and for multiple molecular levels of regulation of renal Na(+)-K(+)-ATPase expression.

Animals↗
PubMed1994

Differential expression and induction of mRNAs encoding two inducible nitric oxide synthases in rat kidney.

We used quantitative PCR methods and renal microdissection to characterize the expression of inducible nitric oxide synthase (iNOS) mRNAs in rat kidney and cultured glomerular mesangial cells. A partial cDNA homologous to murine macrophage iNOS (macNOS), but distinct from rat vascular smooth muscle iNOS (vsmNOS), was cloned from normal rat kidney. macNOS was the principal iNOS isoform tonically expressed in microdissected glomeruli, proximal tubules, medullary thick ascending limbs (mTAL), cortical and inner medullary collecting ducts (IMCD), and cultured mesangial cells, whereas vsmNOS was the major isoform expressed in arcuate and interlobular arteries. Basal macNOS expression was greatest in mTALs and IMCDs. Restriction mapping of RT-PCR products indicated that basal expression of macNOS mRNA was comparable to that of vsmNOS in cortex, but greater than vsmNOS in outer and inner medulla. However, compared to controls, lipopolysaccharide (LPS)-treated rats exhibited a much greater proportion of vsmNOS mRNA and higher levels of total iNOS mRNA in each zone. Similarly, TNF alpha and IF-gamma preferentially induced expression of vsmNOS mRNA in cultured mesangial cells. We conclude that two iNOS isoforms are constitutively and heterogeneously expressed in the normal rat kidney, and that endotoxemia and cytokines differentially induce their expression.

Amino Acid Oxidoreductases↗
PubMed1994

In situ hybridization localization of mRNA encoding inducible nitric oxide synthase in rat kidney.

We used in situ hybridization with a digoxigenin-labeled cRNA for inducible nitric oxide synthase (iNOS) to characterize the intrarenal distribution of iNOS transcripts in normal and lipopolysaccharide (LPS)-treated rats. In normal rats, the S3 segment of the proximal tubule, the cortical and medullary thick ascending limb, the distal convoluted tubule, and the cortical and inner medullary collecting duct were intensely labeled, whereas the thin limbs of Henle, proximal convoluted tubule, outer medullary collecting duct, and medullary interstitial cells were weakly labeled. LPS-treated rats exhibited a similar labeling pattern, but with increased staining of mesangial cells, medullary interstitial cells, and papillary surface epithelium. The renal vasculature, including the afferent arteriole, was not labeled in either group. No cellular labeling was observed when the sections were hybridized with the sense iNOS probe. These results indicate that iNOS mRNA is tonically and differentially expressed along the normal rat nephron and that LPS induces iNOS gene expression in normally quiescent mesangial cells, medullary interstitial cells, and papillary surface epithelium.

Amino Acid Oxidoreductases↗
PubMed1993

Differential expression and cellular distribution of mRNAs encoding alpha- and beta-isoforms of Na(+)-K(+)-ATPase in rat kidney.

We have used in situ hybridization histochemistry with isoform-specific, digoxigenin-labeled cRNA probes to characterize systematically the cellular distribution of mRNAs encoding alpha- and beta-subunit isoforms of the Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) in the normal rat kidney. Transcripts encoding the alpha 1-, alpha 2-, alpha 3-, beta 1-, and beta 2-subunits were detected in virtually all of the nephron segments, with prominent hybridization signal in the S3 segment of the proximal tubule, the cortical and medullary thick ascending limb of Henle's loop, the distal convoluted tubule, the cortical collecting duct along its entire length, and the renal pelvic epithelium. Several differences in the cell-specific pattern of expression of the various isoforms were observed. Among the alpha-isoforms, the alpha 3-subunit appeared to be preferentially expressed in the glomerular podocytes and mesangial cells, papillary interstitial cells, and renal pelvic epithelium. The beta-isoforms also differed in their distribution pattern, with the beta 1-subunit expressed to a greater degree in the glomerulus and renal pelvic epithelium and the beta 2-subunit preferentially expressed in the papillary interstitial cells and papillary surface epithelium. The detection and expression pattern of alpha- and beta-subunit mRNAs in structures throughout the kidney is compatible with the possibility of six structurally unique Na(+)-K(+)-ATPase isozymes and suggests a potentially greater role for isozymes comprised of the alpha 2-, alpha 3-, and beta 2-subunits in renal sodium and potassium transport.

Animals↗
PubMed1993

Differential actions of cisplatin on renal proximal tubule and inner medullary collecting duct cells.

Cisplatin (CP) nephrotoxicity in vivo is characterized by proximal tubule (PT) and collecting duct dysfunction. We reported previously that mitochondrial injury is an important early event in CP toxicity to PT cells and precedes inhibition of Na+,K(+)-ATPase activity and loss of cell K+. In the present study, we monitored oxygen consumption (QO2) and net K+ fluxes in intact inner medullary collecting duct (IMCD) and PT cells in vitro, using O2- and K(+)-sensitive electrodes, to determine if CP has similar effects on IMCD cells. Short-term exposure of IMCD cells to CP resulted in inhibition of spontaneous, ouabain-sensitive and ouabain-oversensitive QO2, but to a lesser degree than in PT. Ouabain-sensitive K+ transport and cell K+ content were also reduced in intact IMCD cells in this setting, confirming inhibition of Na+,K(+)-ATPase activity. In contrast, Na+,K(+)-ATPase activity measured in IMCD cell lysates was not altered. These results suggested that CP inhibited Na+,K(+)-ATPase activity in intact IMCD cells indirectly either by blocking Na+ entry or by inhibiting mitochondrial oxidative phosphorylation. Nystatin (Na+ ionophore) and carbonyl cyanide m-chlorophenylhydrazone (CCCP, uncoupler of oxidative phosphorylation) were used to distinguish between these possibilities. Nystatin-stimulated and CCCP-uncoupled QO2 were reduced in CP-treated IMCD cells by 34 +/- 10% and 25 +/- 5%, respectively, indicating mitochondrial injury. Again, the effects of CP on nystatin-stimulated and CCCP-uncoupled QO2 in IMCD cells were significantly less dramatic than in PT cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Sulfhydryl-reactive heavy metals increase cell membrane K+ and Ca2+ transport in renal proximal tubule.

The cellular mechanisms by which nephrotoxic heavy metals injure the proximal tubule are incompletely defined. We used extracellular electrodes to measure the early effects of heavy metals and other sulfhydryl reagents on net K+ and Ca2+ transport and respiration (QO2) of proximal tubule suspensions. Hg2+, Cu2+, and Au3+ (10(-4)M) each caused a rapid net K+ efflux and a delayed inhibition of QO2. The Hg2(+)-induced net K+ release represented passive K+ transport and was not inhibited by barium, tetraethylammonium, or furosemide. Both Hg2+ and Ag+ promoted a net Ca2+ uptake that was nearly coincident with the onset of the net K+ efflux. A delayed inhibition of ouabain-sensitive QO2 and nystatin-stimulated QO2, indicative of Na+, K(+)-ATPase inhibition, was observed after 30 sec of exposure to Hg2+. More prolonged treatment (2 min) of the tubules with Hg2+ resulted in a 40% reduction in the CCCP-uncoupled QO2, indicating delayed injury to the mitochondria. The net K+ efflux was mimicked by the sulfhydryl reagents pCMBS and N-ethylmale-imide (10(-4) M) and prevented by dithiothreitol (DTT) or reduced glutathione (GSH) (10(-4) M). In addition, both DTT and GSH immediately reversed the Ag(+)-induced net Ca2+ uptake. Thus, sulfhydryl-reactive heavy metals cause rapid, dramatic changes in the membrane ionic permeability of the proximal tubule before disrupting Na+, K(+)-ATPase activity or mitochondrial function. These alterations appear to be the result of an interaction of the metal ions with sulfhydryl groups of cell membrane proteins responsible for the modulation of cation permeability.

Animals↗
PubMed1990

Influence of Na+ intake on dopamine-induced inhibition of renal cortical Na(+)-K(+)-ATPase.

The enzyme L-amino acid decarboxylase (L-AADC), found in abundance in rat proximal tubule cell cytosol, converts L-dopa to dopamine. Dopamine, in turn, suppresses proximal tubule sodium transport by inhibiting Na(+)-K(+)-ATPase activity. We sought to determine whether changes in dietary sodium intake in rats lead to adaptation of dopamine formation and dopamine-induced Na(+)-K(+)-ATPase inhibition. In rats on a high-salt (HS) diet, the maximal velocity (Vmax) of renal cortical L-AADC was 78 +/- 19% higher than that in rats on a low-salt (LS) diet. The Michaelis constant (Km) of the enzyme remained unchanged. In renal cortical tubule cell suspensions the L-dopa-induced inhibition of ouabain-sensitive oxygen consumption (QO2) was significantly greater in rats on HS diet than in rats on LS diet. Furthermore, L-dopa completely inhibited the nystatin-induced rise in QO2 in the HS but not in the LS group. Carbidopa, an inhibitor of L-AADC, abolished the L-dopa-induced inhibition of nystatin-stimulated QO2 in cells from HS rats and was without significant effect in cells from LS rats. L-Dopa-stimulated K+ efflux was greater in cells from HS rats at 28 +/- 1 nmol.min-1.mg protein-1, compared with 7 +/- 6 nmol.min-1.ng protein-1 in cells from LS rats. By contrast, ouabain-stimulated K+ efflux did not differ between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Mitochondrial injury: an early event in cisplatin toxicity to renal proximal tubules.

Oxygen consumption (QO2) and net K+ transport were studied in rabbit proximal tubule suspensions to define the early effects of cisplatin on proximal tubule function. Cisplatin caused dose-dependent inhibition of QO2, which was delayed in onset. The concentration of cisplatin required for inhibition decreased as the duration of exposure was increased [40-min exposure, threshold concentration of 10(-4) M, inhibitor constant (Ki) of 10(-3) M; 4-h exposure, threshold concentration of 3 X 10(-5) M, Ki of 10(-4) M]. Both ouabain-sensitive and ouabain-insensitive QO2 were reduced, indicating inhibition of all adenosinetriphosphatases, including Na(+)- K(+)-ATPase activity. There was a parallel fall in ouabain-sensitive net K+ transport and cytosolic K+ content, confirming the latter observation. Na(+)-K(+)-ATPase activity was unchanged in cell membranes prepared by hypotonic lysis from cisplatin-treated tubules, indicating an indirect cytosol-dependent mechanism of enzyme inhibition. Nystatin-stimulated QO2 was reduced in cisplatin-treated tubules, excluding inhibition of Na+ entry as the mechanism of injury and suggesting mitochondrial injury. The latter was confirmed by measurement of carbonylcyanide-m-chlorophenylhydrazone (CCCP)-uncoupled QO2 in intact cells and ADP-stimulated (state 3) QO2 in digitonin-permeabilized tubules. Furthermore, by maximally stimulating mitochondrial respiration with CCCP and nystatin, it was possible to demonstrate mitochondrial injury at a time when basal QO2 and K+ transport were apparently normal. These data suggest that mitochondrial injury is a central event in cisplatin toxicity to the proximal tubule.

Adenosine Diphosphate↗
PubMed1990

Modulation of osmolytes in MDCK cells by solutes, inhibitors, and vasopressin.

MDCK cells accumulate organic osmolytes in response to hyperosmotic NaCl-supplemented medium. We examined time course and inhibitor sensitivity of myo-inositol, sorbitol, and glycerophosphorylcholine (GPC) accumulation in MDCK cells exposed to hyperosmotic NaCl-, D-glucose-, or mannitol-supplemented media. In NaCl medium, cells preferentially accumulated inositol and GPC. In comparison, in glucose medium cells preferentially accumulated sorbitol and GPC. Inositol demonstrated a late (72-96 h) accumulation in glucose medium, although less than in NaCl medium. Mannitol medium did not significantly stimulate accumulation of any of these three osmolytes at 24 h, suggesting that hyperosmolality alone is not sufficient stimulus for their accumulation in this time frame. GPC accumulation was very rapid in glucose medium, and fell to the level induced by NaCl medium at 96 h (approximately 50 nmol/mg protein). Inositol and sorbitol accumulated more gradually, each reaching greater than 400 nmol/mg protein after 96 h. Sorbitol was still accumulating at 96 h, whereas inositol plateaued at 72-96 h. Phlorizin or sorbinil blocked accumulation of inositol or sorbitol, respectively. Sorbitol and GPC accumulation in glucose medium were partially inhibited in absence of serum or in presence of 1 microM vasopressin. Thus NaCl and glucose appear to stimulate specific cellular mechanisms responsible for accumulation of inositol, sorbitol, and GPC in MDCK cells. This accumulation is also modulated by constituents of serum.

Animals↗