Biomedical subjects

M K Hise

Publications and source records attributed to M K Hise.

At least 19 recordsLinked to original sources

PubMed2001

Control of the epidermal growth factor receptor and its ligands during renal injury.

AIM: We studied control of the epidermal growth factor (EGF) receptor and its ligands during kidney injury, since they may be importantly involved in repair. METHODS: The folic acid model of renal injury was used in these studies. Messenger RNA (mRNA) was evaluated by solution hybridization. Immunohistochemistry of transforming growth factor alpha (TGF-alpha) was also performed. RESULTS: Twenty-four hours after folic acid induced acute renal injury, creatinine increased from 0.3 +/- 0.03 mg/dl in controls to 2.0 +/- 0.8 mg/dl in folic acid injured kidneys (n = 4, p < 0.03). mRNA for the EGF receptor was increased nearly sevenfold by 24 h, and mRNA for the receptor was increased as early as 1 h following folic acid treatment. EGF receptor ligand caused a profound downregulation of the receptors in proximal tubule basolateral membranes, but receptors returned rapidly to the membrane surface in injured kidneys. The mRNA levels for heparin-binding EGF and TGF-alpha, two EGF receptor ligands, increased within 1 h of injury. TGF-alpha mRNA increased from 1.0 +/- 0.09 (relative densitometry units) in control animals to 2.9 +/- 0.13 in folic acid treated rats at 24 h (n = 4, p < 0.01), and immunohistochemical staining for TGF-alpha increased in injured kidneys at distal nephron sites. CONCLUSIONS: These studies indicate that upregulation of the EGF receptor is related to an increase in mRNA. The rapid return of receptors to the membrane surface following ligand stimulation may be useful in maintaining a mitogenic stimulus. Multiple EGF-like ligands may be important in activating the upregulated EGF receptor during repair from renal injury.

Acute Disease↗

PubMed2001

mRNA expression of the IGF system in the kidney of the hypersomatotropic rat.

AIM: To examine the response of the insulinlike growth factor (IGF) system in the kidney during a state of extreme growth. METHODS: We studied the mRNA expression of IGF-I, IGF-I receptor, and IGF-binding proteins (BP) using sensitive RNase protection assays following subcutaneous implantation of growth hormone pituitary cells (GH(3)) in rats. RESULTS: Within 5 weeks, the serum GH levels increased from 18.0 +/- (SE) 5.0 ng/ml in control animals to 389.8 +/- 30.3 ng/ml in GH(3) rats (n = 5, p < 0.001). The circulating IGF-I levels were also elevated. The kidney weights increased from 0.74 +/- 0.01 g in controls to 1.06 +/- 0.03 g in GH(3) animals (n = 5, p < 0.001). Similar changes were observed at week 10. The renal IGF-I mRNA averaged 1.0 +/- (SD) 0.33 relative densitometry units in controls (n = 4) and increased to 2.11 +/- 0.13 relative densitometry units in GH(3) rats (n = 5, p < 0.001). On the other hand, mRNA for the type I IGF receptor decreased in hypersomatotropic rats. Messenger RNAs for IGFBP-1 and IGFBP-4, which have been localized to renal tubules, both decreased significantly following growth induction, while IGFBP-3, the mRNA of which has an interstitial localization, was increased at week 10. CONCLUSION: These data suggest that there is a dynamic relationship between tubular and interstitial compartments with regard to the IGF system in the kidney which may be important in the regulation of the cell mass.

Animals↗

PubMed2000

Mrna expression of transforming growth factor-alpha and the EGF receptor following nephrotoxic renal injury.

We studied gene expression for transforming growth factor (TGF)-alpha, epidermal growth factor (EGF), heparin binding (HB) EGF, and the EGF receptor following acute renal failure induced by mercuric chloride administration to gain insight into potential mechanisms of renal repair. Twenty four hours after HgCl2, 2 mg/kg, creatinine increased from 0.3+/-0.01 mg/dl in controls to 2.2+/-0.26 mg/dl in injured rats (n = 5, p < 0.01). Similar changes were observed after 3 days. Messenger RNA expression for EGF was decreased at 24 hours in HgCl2 treated rats and remained depressed for at least 3 days. On the other hand steady state mRNA for TGF-alpha increased nearly 2 fold at day 3 in HgCl2 treated rats 4 mg/kg. Heparin binding EGF was increased early, by day one in injured kidneys and gene expression for the EGF receptor was increased as well. Immunohistochemistry documented an increase in expression of TGF-alpha in injured kidneys at distal nephron sites. These studies suggest that TGF-alpha along with HB EGF may be important ligands for the EGF receptor during repair from renal injury.

Acute Kidney Injury↗

PubMed2000

Bladder epithelial cells from patients with interstitial cystitis produce an inhibitor of heparin-binding epidermal growth factor-like growth factor production.

PURPOSE: The etiology of interstitial cystitis is unknown. We previously identified an interstitial cystitis urine factor, antiproliferative factor, that inhibits proliferation of bladder epithelial cells in vitro and complex changes in epithelial growth factor levels, including profound decreases in heparin-binding epidermal growth factor-like growth factor (HB-EGF). Bladder and renal pelvic catheterization of patients with interstitial cystitis indicated that the antiproliferative factor is made and/or activated in the distal ureter or bladder. Therefore, we determined whether bladder epithelial cells from interstitial cystitis cases produced the antiproliferative factor and whether purified antiproliferative factor could alter production of growth factors known to be abnormal in interstitial cystitis. MATERIALS AND METHODS: Antiproliferative factor activity was determined by 3H-thymidine incorporation into primary bladder epithelial cells. The antiproliferative factor was purified by size fractionation followed by sequential chromatography involving ion exchange, hydrophobic interaction and high performance liquid chromatography. HB-EGF, epidermal growth factor, insulin-like growth factor and insulin-like growth factor binding protein 3 levels were determined by enzyme-linked immunosorbent assay. RESULTS: Bladder epithelial cells from patients with interstitial cystitis produced a single antiproliferative factor with the same purification profile as that purified from interstitial cystitis urine. Purified antiproliferative factor specifically inhibited HB-EGF production by bladder epithelial cells in vitro, and the effect of interstitial cystitis urine or purified antiproliferative factor on bladder cell proliferation was inhibited by recombinant human HB-EGF in a dose dependent manner. Similar to urine HB-EGF, serum HB-EGF was also significantly lower in interstitial cystitis cases than in controls. CONCLUSIONS: Bladder epithelial abnormalities in interstitial cystitis may be caused by a negative autocrine growth factor that inhibits cell proliferation by down-regulating HB-EGF production. Furthermore, decreased levels of urine and serum HB-EGF indicate that interstitial cystitis may be a urinary tract manifestation of a systemic disorder.

Cell Division↗

PubMed1998

A diagnostic in vitro urine assay for interstitial cystitis.

OBJECTIVES: A low molecular weight urine factor that inhibits the proliferation of normal bladder epithelial cells in vitro was previously shown to be present significantly more often in the urine of patients with interstitial cystitis (IC) than in the urine of asymptomatic age-, race-, and sex-matched control subjects. We sought to determine the specificity of this finding for IC by determining whether the urine of patients with other urogenital inflammatory disorders also contains a factor that inhibits bladder epithelial cell proliferation. METHODS: Urine was collected from women with IC, acute bacterial cystitis, or vulvovaginitis, as well as from asymptomatic control women. The proliferation of primary normal adult bladder epithelial cells was determined by measuring 3H-thymidine incorporation in vitro. RESULTS: Osmolality- and pH-corrected urine specimens from 50 (86%) of 58 women with IC significantly inhibited human bladder epithelial cell proliferation compared with 3 (8%) of 36 asymptomatic control women, 7 (12%) of 58 women with bacterial cystitis, and 0 (0%) of 12 women with vulvovaginitis (P < 0.001 for the comparison of mean percent change in 3H-thymidine incorporation with IC urine versus urine from each of the control groups). Optimal sensitivity and specificity values of 91.4% and 90.6%, respectively, were achievable at a cutoff of 25% inhibition of 3H-thymidine incorporation, using all three control groups. CONCLUSIONS: The measurement of urine antiproliferative activity may be a useful noninvasive means for diagnosing IC in women.

Adult↗

PubMed1997

Concentrations of specific epithelial growth factors in the urine of interstitial cystitis patients and controls.

PURPOSE: Interstitial cystitis (IC) is a chronic bladder disease for which the etiology is unknown. Because the bladder epithelium is often abnormal in IC, we determined whether the levels of specific urine growth factors postulated to be important for bladder epithelial proliferation are altered in IC. MATERIALS AND METHODS: ELISAs were used to determine levels of epidermal growth factor (EGF), insulin-like growth factor 1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3), and heparin binding epidermal growth factor-like growth factor (HB-EGF) in urine specimens from women with IC, asymptomatic women without bladder disease, and women with bacterial cystitis. RESULTS: Urine HB-EGF levels were specifically and significantly decreased in IC patients as compared to asymptomatic controls or patients with bacterial cystitis, whether expressed as concentration (amount per volume of urine) or the amount relative to urine creatinine in each specimen. In contrast, urine EGF, IGF1, and IGFBP3 levels were all significantly elevated in IC patients compared to asymptomatic controls. Further, the amounts of urine EGF and IGF1 were also elevated in IC patients as compared to patients with bacterial cystitis, and urine IGFBP3 levels were significantly elevated when expressed per milligram of urine creatinine. CONCLUSIONS: These findings indicate that complex changes in the levels of urine epithelial cell growth factors (EGF, IGF1, and HB-EGF) and a growth factor binding protein (IGFBP3) are associated with IC. While EGF, IGF1, and IGFBP3 levels are either the same or increased in the urine of IC patients as compared to patients with bacterial cystitis or asymptomatic controls, HB-EGF levels are significantly decreased in the urine of IC patients. Understanding the reasons for these changes may lead to understanding the pathogenesis of this disorder.

Adult↗

PubMed1997

Expression of the insulin-like growth factor system in the hypokalemic rat kidney.

We studied the renal expression of the insulin-like growth factor (IGF) system to gain a better perspective of its potential role in the hyperplastic adaptation of the distal nephron to potassium deficiency. Rats were pair fed 1% or 0.002% potassium diets for periods up to 10 days. IGF-I mRNA was diminished in potassium-deficient rats within 4 days, whereas mRNA for IGF binding protein-1 (IGFBP-1), a collecting duct-associated protein, was increased by day 7. At day 10 mRNA for IGFBP-1 in potassium-deficient animals averaged 2.07 +/- 0.53 (mean +/- SD, relative densitometry units) compared with 0.89 +/- 0.26 in control rats (n = 4, P = 0.002). Conversely, IGFBP-3, a binding protein whose mRNA has been localized to the interstitial compartment, averaged 2.40 +/- 0.02 in potassium-deficient rats and 4.77 +/- 0.05 in controls (n = 4, P < 0.03) at day 10 of treatment. Immunohistochemistry performed using a specific IGFBP-1 antibody revealed hyperplasia of distal nephron segments along with an increase in IGFBP-1 in potassium-depleted rats. These data suggest that IGFBP-1 may play an important role in the control of cellular adaptations in the hypokalemic rat kidney either directly by influencing cell migration or indirectly by localizing IGF-I to the distal nephron.

Animals↗

PubMed1996

Transforming growth factor-alpha expression in human renal cell carcinoma: TGF-alpha expression in renal cell carcinoma.

OBJECTIVES: To characterize the expression of transforming growth factor-alpha (TGF-alpha) in various histologic types of renal cell carcinomas. METHODS: Immunohistochemistry of renal cell carcinoma and adjacent normal tissue was performed on formalin-fixed tissue using a specific monoclonal antibody to TGF-alpha. RESULTS: Clear and distinct staining was present in normal distal convoluted tubules and collecting ducts. The growth factor was not observed in the glomerulus or the proximal tubule. In tumors composed of clear cells, staining was evident only in endothelial cells but not in the tumor cells themselves. In granular cell type tumors, the tumor cells as well as endothelial cells stained for TGF-alpha. When mixed cell type tumors were studied, a heterogenous pattern of growth factor expression was found. Endothelial cells and granular cells but not clear cells demonstrated positive staining. CONCLUSIONS: These studies suggest that TGF-alpha is likely to play a major role in neovascularization of clear cell carcinomas and that the growth factor may be more important in supporting proliferation of granular cell type tumors.

Carcinoma, Renal Cell↗

PubMed1996

Decreased 3H-thymidine incorporation by human bladder epithelial cells following exposure to urine from interstitial cystitis patients.

PURPOSE: Interstitial cystitis (IC) is a chronic bladder disease of unknown etiology. We sought to determine whether a cytotoxin is present in the urine of IC patients that could cause the epithelial damage seen in this disease. MATERIALS AND METHODS: Evidence for a cytotoxin was sought using both a neutral red uptake viability assay in T24 bladder epithelial cells, and a 3H-thymidine incorporation assay in primary normal adult bladder epithelial cells and FHS 738 Bl human fetal bladder cells. RESULTS: The neutral red assay in T24 cells indicated the presence of a cytotoxin in 2 of 9 IC patient urine specimens. However, the more sensitive assay of cell proliferation (3H-thymidine incorporation) in normal adult human bladder epithelial cells revealed antiproliferative activity in urine from 10 of 13 (77%) IC patients vs. 3 of 19 (16%) controls (two-way analysis of variance, p = .019). The antiproliferative activity of IC urine specimens was confirmed using FHS 738 Bl human fetal bladder cells. The antiproliferative urinary substance(s) appeared to be a low molecular weight (< 10,000 Da), heat stable, trypsin-sensitive factor(s). CONCLUSIONS: Because a denuded or damaged bladder epithelium is a central finding in IC, it is possible that the antiproliferative protein(s) contributes to the pathogenesis of this disease.

Adult↗

PubMed1995

Differential mRNA expression of insulin-like growth factor system during renal injury and hypertrophy.

The cellular effects of insulin-like growth factor I (IGF-I) are modified by a family of binding proteins (IGFBPs) that act as reservoirs in serum for the growth factor and are produced locally by tissues, including the kidney. Because regulation of these proteins may influence renal repair, either directly or by their interactions with IGF-I, we studied gene expression during the recovery from renal failure induced by folic acid and during the compensatory increase in renal function following uninephrectomy (UNX). Expression of IGF-I, the IGF-I receptor (IGF-IR), and all six IGFBPs was detected using an ribonuclease protection assay. IGFBP-5 was the most abundant binding protein mRNA present in kidney, whereas IGFBP-2 and -6 were the least abundant. During regeneration following folic acid-induced acute renal failure, IGF-I, IGFBP-3, and IGFBP-5 mRNAs declined in abundance approximately two- to threefold. On the other hand, IGF-IR, IGFBP-1, and IGFBP-2 were increased (approximately 2-, 6-, and 6-fold, respectively) in the first 24 h. IGFBP-1 mRNA remained elevated for at least 3 days. Despite the known increase in cellular RNA content following UNX, little difference in specific expression of mRNAs was observed. Because IGFBP-1 has been shown to stimulate cell migration and has previously been localized to the distal nephron, the site of greatest injury in the folic acid model, these data are compatible with the notion that this protein may function either directly to affect cellular repair or act as a reservoir for IGF-I under conditions of cellular damage.

Animals↗

PubMed1994

Low-protein diet regulates a proximal nephron insulin-like growth factor binding protein.

Previous studies have demonstrated that the glomerulus and proximal tubule basolateral membrane possess both insulin-like growth factor (IGF) receptors and IGF-binding proteins (IGFBPs). The purpose of this study is to examine the control of these proteins in defined nephron segments during dietary protein restriction. Animals were fed isocaloric 6% (low-protein [LP]) or 40% (high-protein) protein diets for 7 to 10 days. 125I[IGF] affinity labeling of membranes prepared from isolated glomeruli or proximal tubule basolateral membranes demonstrated two proteins on autoradiograms of 6% polyacrylamide gels with molecular weights of 140,000 d and more than 200,000 d that were blocked by 300 nmol/L unlabeled IGF-I. The lower molecular weight species has been identified previously as the alpha subunit of the IGF-I receptor and was upregulated by a 6% LP diet. The upregulation of the IGF-I receptor was evident on 12% polyacrylamide gels of both glomeruli and basolateral membranes. Another protein with a molecular weight of approximately 38,000 d also was upregulated by LP diet. The protein was evident on 125I-IGF-I ligand blots and was immunostained with IGFBP-5 antibodies. Cytosol prepared from cortical tissue also demonstrated a 31,000-d protein that was immunostained with IGFBP-5 antibodies in animals fed a LP diet, but not in animals fed a high-protein or normal diet. RNA prepared from cortical tissue and hybridized with a IGFBP-5 cDNA probe revealed a 6.0-Kb transcript that was increase by LP diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗

PubMed1994

IGF binding protein 5 and IGF-I receptor regulation in hypophysectomized rat kidneys.

This study examines growth-regulating adaptations made by the proximal nephron in response to hypophysectomy (HYPX). Fourteen days after HYPX, circulating insulin-like growth factor I (IGF-I) levels were diminished, averaging 97 +/- 7 compared with 650 +/- 69 ng/ml in controls (n = 5, P < 0.001). Similar data were observed at day 7. Binding of 125I-IGF-I to isolated glomerular membranes and proximal tubule basolateral membranes (BLM) was increased in HYPX rats. Affinity labeling of membranes with 125I-IGF-I followed by electrophoresis on 6% polyacrylamide gels demonstrated two bands, one of approximately 140 kDa and another of > 200 kDa. The lower-molecular-mass protein, which has been identified as the alpha-subunit of the IGF-I receptor, and the higher-molecular-mass species were both upregulated by HYPX. Ligand blotting with IGF-I demonstrated a 31-kDa protein in both membranes, identified by immunostaining as IGF binding protein 5 (IGFBP-5), not IGFBP-1 or IGFBP-2. Affinity labeling documented an upregulation of this protein in both membranes after HYPX. Ligand blotting demonstrated a 31-kDa protein in HYPX cortical but not normal cortical or medullary cytosol that was immunostained with IGFBP-5 antibodies. RNA prepared from normal kidney cortical tissue demonstrated a 6.0-kb IGFBP-5 transcript, which was increased at day 14 after HYPX. Adaptations in the kidney after HYPX include an upregulation of the IGF-I receptor as well as IGFBP-5.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1993

Regulation of epidermal growth factor receptor expression and growth by protein kinase C and retinoic acid in LLC-PK1 cells.

The importance of receptor expression and protein kinase C to epidermal growth factor (EGF)-induced cell proliferation was studied in LLC-PK1 kidney cells. These cells have both high- and low-affinity binding sites for EGF. Neither transforming growth factor-beta nor tumor necrosis factor altered EGF receptor expression. On the other hand, retinoic acid induced a concentration-dependent increase in EGF binding that was maximal at 1 mumol/L. One micromolar of retinoic acid increased EGF binding from 0.38 +/- 0.01 fmol/10(6) cells in controls to 1.10 +/- 0.03 fmol/10(6) in treated cells at 18 hours (n = 8, P < 0.001). The increase in binding was the result of an increase in the Bmax of the high-affinity receptor. The upregulation of the EGF receptor induced by retinoic acid was associated with enhanced EGF-induced growth promotion. A 45-minute incubation of cells with phorbol 12-myristate 13-acetate caused a concentration-dependent decrease in EGF binding that was prevented by a 40-hour, 2 mumol/L pre-exposure to phorbol 12-myristate 13-acetate; 10(-8) mol/L EGF also caused a downregulation of the EGF receptor that was not prevented by phorbol 12-myristate 13-acetate or retinoic acid. Downregulation of protein kinase C did not interfere in the capacity of EGF to induce growth in these cells. These studies demonstrate that EGF receptor upregulation plays an important role in the control of EGF-induced cell growth. Protein kinase C regulates EGF binding in these cells; however, it is not necessary for EGF-induced growth promotion or receptor downregulation.

Cell Division↗

PubMed1993

Insulin-like growth factor-I receptor and binding proteins in rat kidney after nephron loss.

Insulin-like growth factor (IGF)-binding proteins and the IGF-I receptor in rat kidney were studied to gain perspective on their potential roles in the control of renal cell mass. Thirty days after nephrectomy (UNx), membranous whole-kidney binding of IGF-I averaged 9.5 +/- 1.0 pmol/kidney, whereas binding to sham-operated controls (SNx) averaged 6.3 +/- 0.8 pmol/kidney (N = 6; P < 0.01). Scatchard analysis of IGF-I binding per milligram of protein to glomerular membranes or proximal tubule basolateral membranes (BLM) at Day 30 did not reveal significance differences in Bmax or KD between SNx and UNx; however, protein per glomerulus increased from 361 +/- 33 ng/glomerulus in SNx animals to 826 +/- 123 ng/glomerulus in UNx rats (N = 6; P < 0.002). Histomorphometrics documented an increase in proximal tubule circumference per cell and an increase in the basolateral/basement membrane ratio. IGF-I affinity labeling studies demonstrated three proteins in both glomerular membranes and proximal tubule BLM; molecular weight approximately 140,000 d, the alpha subunit of the IGF-I receptor, a protein > 200,000 d, and a protein approximately 31,000 d that was immunostained with IGF-binding protein-5 antibodies. Differences in expression between SNx and UNx were not observed at Day 30 in either glomeruli or BLM. These studies suggest that cytosolic hypertrophy of proximal nephron structures is accompanied by membrane hypertrophy with a fixed density of IGF-I receptor and IGF-binding protein-5.

Animals↗

PubMed1992

Influence of circulating insulin-like growth factor-I compared with that of intrarenal insulin-like growth factor-I on proximal nephron receptor density in rats.

1. We examined the effects of dietary protein manipulations in partially nephrectomized (one and one-third nephrectomy) and normal rats to gain perspective on the relative importance of circulating versus intrarenal (collecting tubule) insulin-like growth factor-I in the control of proximal nephron receptor density. In addition, we studied the factors that influence liver insulin-like growth factor-I secretion in partially nephrectomized rats. 2. Dietary protein restriction (6% versus 40%) lowered circulating levels of insulin and insulin-like growth factor-I in both normal and partially nephrectomized rats up to 3 weeks after institution of the diets; however, growth hormone levels were little changed. Reduced renal mass stimulated intrarenal production of insulin-like growth factor-I regardless of the diet. 3. Scatchard analysis revealed that the density of insulin-like growth factor-I receptors on glomerular and proximal tubule basolateral membranes increased when circulating levels of insulin-like growth factor-I were diminished, despite raised levels of intrarenal insulin-like growth factor-I, in partially nephrectomized rats. 4. Circulating insulin-like growth factor-I, rather than the tissue level, plays the dominant role in the control of proximal nephron receptor density under physiological conditions. Insulin, but not growth hormone, may play a role in liver insulin-like growth factor-I secretion in partially nephrectomized rats during dietary manipulations.

Animals↗

PubMed1991

Hypertensive renal damage.

The primary focus of both nonpharmacologic and pharmacologic therapy should be to control systemic blood pressure in a simple, affordable, and nontoxic fashion that provides an adequate quality of life. Although newer agents provide hope for greater capability of preventing renal dysfunction, their cost may prevent their broad availability in the black hypertensive population (see Chapter 5). Judicious use of traditional therapies, combined with newer approaches when possible, may offer prescribing physicians the best opportunity to control blood pressure in ways to avoid renal dysfunction. The lessons of the past 20 years have taught us that lowering blood pressure by any means helps in reducing target organ damage. More recent observations in hypertensive blacks illustrate the need for improved therapies to prevent renal dysfunction. A more physiologic approach to blood pressure control in the black patient that conserves perfusion to the kidney may delay the development of nephrosclerosis. Increased awareness, educational support, and encouragement will be necessary to insure compliance with therapy for a disease that is largely asymptomatic.

Aging↗

PubMed1990

Regulation of ornithine decarboxylase in rat kidney.

Known stimulators of the calcium-sensitive phospholipid-dependent protein kinase C were investigated for their ability to regulate ornithine decarboxylase (ODC) activity in rat kidney. In the control state ODC activity averaged 84.9 +/- 13.2 pmol mg-1 min-1 in a soluble fraction (n = 4). Four hours following the intraperitoneal injection of 2.5 nmol/g body weight of phorbol 12-myristate 13-acetate (PMA) activity increased to 284.1 +/- 10.9 pmol mg-1 min-1 (n = 4; p less than 0.001). A chemically distinct stimulator of PKC, mezerein, had a similar effect on ODC in kidney and liver. Activity stimulated by PMA in kidney was dependent on the synthesis of both new mRNA and protein. Four hours following unilateral nephrectomy (UNX), ODC activity increased from 112.9 +/- 15.6 pmol mg-1 min-1 in sham-operated animals to 319.1 +/- 30.0 pmol mg-1 min-1 in animals postnephrectomy (n = 4; p less than 0.01). Activity of ODC stimulated by phorbol esters was not additive to that seen following UNX. Twelve hours following the induction of renal growth by folic acid. ODC-specific activity was at basal levels. Neither UNX nor PMA were able to stimulate ODC at this time. These data suggest that protein kinase C may be involved in the regulation of ODC in rat kidney.

Animals↗

PubMed1989

Activity of calcium-sensitive phospholipid-dependent protein kinase C following nephron loss.

The localization and activity of the calcium-sensitive phospholipid-dependent protein kinase C (PKC) were examined following the loss of 50% of functioning nephron mass. Four hours following unilateral nephrectomy in rats, soluble (100,000 g supernatant) proteins in the contralateral kidney were increased by 11% compared to sham operated controls; the increase was 33% 144 hours following surgery. The specific activity of PKC did not change in the cytosol at any of the time periods examined and averaged 63.9 +/- 8.2 pmol.mg-1.min-1 in unilaterally nephrectomized animals four hours following surgery. Four hours following sham surgery total soluble PKC activity averaged 1667.0 +/- 278.4 pmol.kidney-1.min-1, whereas activity averaged 3067.7 +/- 415.4 pmol.kidney-1.min-1 in animals post-nephrectomy (N = 5, P less than 0.04). Similar data was seen 144 hours following surgery. To examine the PKC activity in plasma membranes of proximal tubular cells, brush border membranes were prepared from rat kidney cortex. Twenty-four hours following unilateral nephrectomy, activity averaged 193.8 +/- 14.9 pmol.mg-1.min-1, while activity in membranes isolated from sham operated animals averaged 76.6 +/- 8.0 pmol.mg-1.min-1 (N = 5, P less than 0.001). Similar data was evident 48 hours following surgery. A small increment in activity was seen in the basolateral membrane preparation 24 hours following unilateral nephrectomy but not at 48 hours. These data indicate that cellular PKC activity increases rapidly following reductions in renal mass, and there are selective increments in the brush border membrane of the proximal tubular cell. The localization of PKC to this membrane may have important consequences for adaptations following nephron loss.

Acid Phosphatase↗