(Hypertension. 1995;26:905-911.)
© 1995 American Heart Association, Inc.
Articles |
Effect of Hypothalamic-Hypophysary Inhibitory Factor on Mesangial Cell Activation
From Instituto Reina Sofía de Investigación Nefrológica, Departamento de Fisiología y Farmacología, Universidad de Salamanca (A.R.-B., C.M.-S., A.M.R.-L., J.M.L.-N.) and Servicio de Endocrinología, Hospital Ramón y Cajal, Madrid (M.R., J.S.), Spain.
Correspondence to Dr José M. López-Novoa, Departamento de Fisiología y Farmacología, Edificio Departamental, Universidad de Salamanca, Avda. Campo Charro s/n, 37007 Salamanca, Spain.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Abstract We examined the effect of a sodium pump inhibitor isolated from bovine hypothalamus and pituitary tissues on contraction, proliferation, and calcium mobilization in primary cultures of rat mesangial cells. Hypothalamic-hypophysary inhibitory factor (HHIF) inhibited rubidium uptake in a concentration-dependent manner (0.2 U/mL: 56.8±6.3% inhibition). It also induced a concentration- and time-dependent decrease in planar cell surface area. Maximal contraction (25±5% reduction in cell size) was reached at 60 minutes with a concentration of 0.2 U/mL. This effect was inhibited by both verapamil and TMB-8 (10-5 mol/L). HHIF was also observed to increase DNA synthesis (0.2 U/mL: 4361±168 versus 2129±162 cpm per well under control conditions) and cell proliferation (0.2 U/mL: 52 290±1931 versus 10 512±121 cells per well under control conditions). Both effects were also inhibited by verapamil and TMB-8. Moreover, HHIF induced the expression of immediate early genes c-fos and c-jun mRNA. HHIF-induced effects were accompanied by an increase in cytosolic free calcium (203±58 versus 101±2 nmol/L under control conditions), which was inhibited by verapamil and TMB-8. In summary, HHIF induces mesangial cell contraction and proliferation; these effects seem to be mediated by an increase in cytosolic free calcium levels.
Key Words: mesangium, glomerular • hypertension, essential • Na+,K+-transporting ATPase • genes
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The physiological abnormality underlying essential hypertension is a rise in peripheral vascular resistance caused by increased VSMC tone. It is generally assumed that the pathophysiology of essential hypertension involves generalized alterations in membrane transport leading to a relatively decreased renal sodium excretion and expansion of plasma volume.1 One widely discussed theory that reconciles these phenomena affords a pivotal role in the etiology of essential hypertension to a humoral factor able to inhibit Na+,K+-ATPase activity. Plasma volume expansion secondary to an unknown renal tubular defect would increase plasma concentrations of these humoral factors with digitalis-like properties, which would thus become able to inhibit the sodium pump.2 Inhibition of active sodium transport may lead, by several possible pathways, to a rise in [Ca2+]i and subsequent increased vascular tone and blood pressure.3 Hypertension is also associated with abnormalities in vascular smooth muscle growth and glomerulosclerosis. A role for a circulating Na+ transport inhibitor in VSMCs and mesangial cell proliferation has been described.4 5 Recently, Hamlyn et al6 and Mathews et al7 purified from human plasma an endogenous inhibitor that has been characterized as ouabain.
Haupert and Sancho8 have suggested that one endogenous sodium transport inhibitor is synthesized in the hypothalamus; the factor isolated from hypothalamus by Haupert's laboratory9 has been characterized as a ouabain isomer.10 A low-molecular-weight, nonpeptide, nonlipid Na,K-ATPase inhibitory factor has been isolated and purified from bovine hypothalamus and hypophysis and has been called HHIF.11 This factor has also been extracted from other tissues and human plasma.12 In contrast to ouabain, HHIF inhibits the Ca2+ pump13 and does not have ouabain-like cross-reactivity.11
Among the multiple events associated with proliferation, the first nuclear response is an increased expression of immediate early genes, which are thought to be critically involved in the control of the cell cycle.14 15 The induction of immediate early gene expression is independent of protein synthesis. Among the members of this group are c-fos, c-jun, and early growth response-1 (Egr-1), all of which encode transcription factors.16 The gene products of c-fos and c-jun form the heterodimer activating protein–1 (AP-1), which is a DNA-binding complex that regulates the transcription of other genes.
In the present study we examined the effects of HHIF on contraction, proliferation, expression patterns of immediate early genes, and calcium mobilization of cultured rat mesangial cells.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Materials
Collagenase type IA from Clostridium histolyticum, TMB-8, L-glutamine, sodium selenite, transferrin and insulin (human), and fura 2–AM were purchased from Sigma Chemical Co. Penicillin was obtained from Laboratorios Level SA. Streptomycin sulfate was obtained from Antibioticos SA. RPMI 1640, Hanks' balanced salt solution, trypsin-EDTA solution, and FCS were obtained from Whittaker Laboratories. [3H]Thymidine and 86Rb were purchased from New England Nuclear. Verapamil was a gift of Knoll AG. Wistar rats were purchased from Charles River (Rouan, France). All other reagents were of the highest grade commercially available.
HHIF Extraction and Purification
HHIF was extracted from 1 kg frozen bovine hypothalamus
and hypophysis, purified following chromatographic
procedures, and physicochemically characterized as previously
reported.11 The purified material has chemical and
chromatographic characteristics different from any known
cardioglycoside.11 12 Each bath of purified material was
tested for purity as previously described.11 12 13 In
essence, the homogeneous material underwent
chromatography in two different
chromatographic systems,12 and we again
obtained a single, symmetrical peak with an identical spectrum and
biological activity as the one of the purified material, suggesting the
purity of the final product. This purified factor revealed by mass
spectrometric analysis a single unique molecular ion with an
accurate mass of 412 277 and mass spectra different from ouabain
(unpublished data, 1995). Its ability to inhibit Na,K-ATPase from
porcine renal outer medulla has been tested for each batch as
previously reported,11 and 1 U was defined as the amount
of HHIF required to inhibit the activity of 8 µg purified Na,K-ATPase
by 50%.
Mesangial Cell Culture
Glomeruli isolated by successive mechanical sieving (150 and 50
µm) from Wistar rats (150 to 200 g) previously anesthetized
with ether were treated with 300 U/mL collagenase, plated
in 25-mm2 plastic tissue culture bottles (Nunc), and
maintained under previously described conditions.17 18 The
culture medium consisted of RPMI 1640 supplemented with 0.1 FCS,
L-glutamine (1 mmol/L), penicillin (50 IU/mL), and
streptomycin sulfate (0.034 mmol/L) and was buffered with bicarbonate.
This culture medium was changed every 2 days. Studies were performed on
day 21 or 22. Characterization of culture cells as
mesangial cells was confirmed by morphological and
functional criteria, strellate aspect, absence of factor VII,
contraction with angiotensin II, and absence of
growth inhibition with the substitution of L-valine for
D-valine, described previously.17 18
Experiments were performed on cultures approaching confluence from the
first passage in order to avoid cell dedifferentiation.
86Rb Uptake
Cells were subcultured by treatment with 0.05% trypsin and
0.02% EDTA and plated in 6x4-well plates (Nunc). Cells were incubated
with agonists at 37°C over 10 minutes and then pulsed with 1 µCi/mL
86Rb (0.5 mmol/L) during 15 minutes. The cell layers were
washed three times with ice-cold culture medium and fixed with 0.5
mL ice-cold 0.1 trichloroacetic acid; acid-insoluble
material was solubilized with 0.5 mL of 0.1 mol/L NaOH for 30 minutes
at 60°C. After NaOH exposure cells were scraped off and removed;
radioactivity was measured on a gamma scintillation counter (Gammamatic
1, Kontron Instruments).
Determination of Planar Surface Area of Mesangial
Cells
Direct observation of mesangial cells in plastic
flasks was carried out at room temperature under phase contrast with an
inverted Nikon photomicroscope with the use of a CCD videocamera (model
KP 110, Hitachi Denshi Ltd) and monitor (model VM-921E, Hitachi). With
the use of an on-line videoprinter (Sony UP-910) serial photographs
of the cells were taken before and after the addition of test
substances. Five to 10 cells were analyzed per photograph. In
each experimental block all the cells were from a single culture.
Experiments were done in triplicate. Planar surface was determined by
computerized image analysis with an IBAS II
image-analyzer system (Kontron Instruments). Actual areas
were calculated after correction for microscope and photographic
magnification.
Measurement of [Ca2+]i
Measurement of [Ca2+]i was
performed as previously reported.19 Fluorescence
was measured at 37°C with a fluorescence spectrophotometer
provided with a thermostatically controlled cuvette holder
(Perkin-Elmer LS50) at an emission wavelength of 510 nm. An excitation
wavelength of 340 nm was chosen for monitoring of the
Ca2+-induced shift in fura 2 fluorescence as
determined by previous calibration determinations.
Autofluorescence, as measured in cells under similar
conditions except that they were not loaded with fura 2, was found to
be less than 10% of the total fluorescence determined in fura
2–loaded cells in all the experiments.
[Ca2+]i was calculated as
described by Olivera and López-Novoa.19
Proliferation Studies
Cell proliferation was measured by [3H]thymidine
uptake into DNA and by measurement of viable cell numbers. For this
purpose cells were subcultured by treatment with 0.05% trypsin and
0.02% EDTA and plated in 6x4-well plates. Mesangial cells
were rendered quiescent by removal of the serum-containing growth
medium. Cells were incubated for 2 days with similar culture medium
except that it contained a low amount (0.005) of FCS. During this time
the cells were observed to incorporate a very low amount of
[methyl-3H]thymidine, indicating the quiescent state. At
this point the cells were reactivated by exposure to
culture medium containing the substances to be tested. The conditions
tested included cell exposure to quiescent medium alone (basal
conditions); 0.2, 0.02, and 0.002 U/mL HHIF;
10-5 mol/L verapamil;
10-5 mol/L TMB-8; and medium containing
0.1 FCS as a positive control. After 18 hours of incubation the cells
were pulsed for 6 hours with 1 µCi/mL
[methyl-3H]thymidine. Cell layers were washed with
ice-cold phosphate-buffered saline and fixed with 1 mL
ice-cold 0.1 trichloroacetic acid for 15 minutes;
acid-insoluble material was solubilized with 1 mL of 0.1 mol/L NaOH
for 30 minutes at 60°C. After NaOH exposure radioactivity was
determined on a scintillation counter (Betamatic IV, Kontron
Instruments).
We also checked the number of viable cells in each well using a commercial modification (Cell Titter 96, Promega) of the method of Hansen et al.20 In brief, cells subcultured to subconfluence in 24-well plates were rendered quiescent as described above. Cells were then incubated for 24 hours with culture medium and the substances described above. The medium was removed and 1 mL fresh incubation medium was added. Then, 150 µL of a solution of tetrazolium bromide salt [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, 5 mg/mL] was added to each well. The plate was returned to the incubator (Ultima; Revco Scientific, Inc) for 4 hours, after which 1 mL of the solubilization solution containing sodium dodecyl sulfate and N,N-dimethyl formamide, pH 4.7, was added. After 1 hour at room temperature the contents of the well were mixed thoroughly with a Pasteur pipette to obtain a uniform color. The contents of the wells were then transferred to a cuvette and read at 570 nm on a spectrophotometer (Shimadzu UV-120-02). Optical density at 570 nm was proportional to the number of viable cells in each well.5
c-fos and c-jun Gene
Expression
Mesangial cells were rendered quiescent by removal
of the serum-containing growth medium and incubation for 3 days
with similar culture medium without FCS. Cells were treated with 0.2
U/mL HHIF, and cells treated with 0.1 FCS were used as positive
controls. After 30 minutes of stimulation mRNA was extracted from
5x105 cells by NP-40 lysis.21 The RNA (1 to 2
µg) was subjected to a reverse transcription reaction with the use of
oligo(dT) primers (Promega). cDNA was amplified by PCR with
oligonucleotides derived from two adjacent exons of the
actin gene, c-fos gene, and c-jun gene with the
use of a thermal cycler (Dual Cycler, Linus) and amplitaq DNA
polymerase.22 Oligonucleotides were
synthesized at the Department of Microbiology and Genetics, University
of Salamanca, and their sequences were as follows: FOS 1:
5'-CAGCCGACTCCTTCTCCAG-3'; FOS 2: 5'-GCCACGGAGGAGACCAGAGT-3'; JUN 1:
5'-GACCTTCTACGACGATGC-3'; JUN 2: 5'-CAGCGCCAGCTACTGAGGC-3'; ACT 1:
5'-AGGCCAACCGCGAGAAGATGACC-3'; and ACT 2:
5'-GAAGTCCAGGGCGACGTAGCAC-3'.
The amplification conditions consisted of denaturing at 94°C for 2 minutes, annealing at 60°C for 2 minutes, and extension at 72°C for 2 minutes. The number of cycles was 25. PCR products were size-fractionated by agarose gel electrophoresis. After staining with ethidium bromide, DNA bands were visualized with a UV transilluminator (Vilber Lourmat TF-35M).
Statistical Methods
In proliferation studies each value is the mean of three wells.
Data were obtained as the average of 4 to 12 values. Comparisons
between means of multiple groups were analyzed by one-way
ANOVA and Scheffé's multiple comparisons test. Time course
studies were analyzed by two-way ANOVA.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Effect of HHIF on 86Rb Uptake
HHIF decreased 86Rb uptake by mesangial cells in a concentration-dependent manner. Inhibition with the highest concentration of HHIF used (0.2 U/mL) was stronger than that with 10-4 mol/L ouabain, a submaximal concentration used to compare the effect of HHIF with a well-known Na+-pump inhibitor (Table).
|
Effect of HHIF on Mesangial Planar Cell Surface
Area
After 60 minutes of incubation HHIF decreased
mesangial planar cell surface area. This effect was
concentration- and time-dependent (Figs 1 and 2). By contrast, no significant changes were observed at
that time in cells incubated under control conditions.
|
|
Preincubation of mesangial cells with the calcium antagonist verapamil (10-5 mol/L), a voltage-dependent calcium channel inhibitor, significantly blunted the contractile response to HHIF (0.2 U/mL). In addition, TMB-8 (10-5 mol/L), an inhibitor of Ca2+ release from the endoplasmic reticulum, also blunted the response to HHIF (Fig 2).
Effect of HHIF on [Ca2+]i
HHIF induced a slow and progressive increase in
[Ca2+]i from resting levels in a
concentration-dependent manner (Fig 3). The lowest concentration used in our
experiments (0.002 U/mL) did not produce any change in
[Ca2+]i, but higher
concentrations (0.02 and 0.2 U/mL) induced a statistically significant
increase in [Ca2+]i. This increase was
time dependent, with a maximal increase in
[Ca2+]i of approximately twofold the
basal values at 10 minutes (Fig 3).
Verapamil (10-5 mol/L) and
TMB-8 (10-5 mol/L) blunted the response
to HHIF (0.2 U/mL) (Fig 4).
|
|
Effect of HHIF on Cellular Proliferation
HHIF also stimulated [3H]thymidine incorporation
into DNA. This effect was significant at concentrations of 0.2 and 0.02
U/mL (Fig 5A). Verapamil
(10-5 mol/L) abolished HHIF (0.02 and 0.2
U/mL)–stimulated thymidine incorporation into DNA (Fig 6). TMB-8
(10-5 mol/L) also blocked the
HHIF-induced effect on thymidine incorporation into DNA (Fig 6).
|
|
A dose-dependent increase in the number of viable cells after 24 hours of incubation in the presence of HHIF was observed (Fig 5B). This effect was partially inhibited by verapamil (10-5 mol/L) and TMB-8 (10-5 mol/L) (Fig 7).
|
c-fos and c-jun Expression
Fig 8 shows representative agarose
gel electrophoresis of amplification products by reverse
transcriptase–PCR of c-fos, c-jun, and actin
genes. In cells treated for 30 minutes with 0.1 FCS, cDNA amplification
gave a band of approximately 195 bp, which is consistent with
the calculated size of the c-fos gene (Fig 8A, lane 2). Treatment with 0.2 U/mL HHIF induced the
expression of c-fos mRNA (Fig 8A, lane 3);
this expression was not observed in quiescent cells (Fig 8A, lane 1). A band of approximately 310 bp,
corresponding to the calculated size of the actin gene, appeared with
all treatments (Fig 8).
|
Expression of the c-jun gene (440 bp) (Fig 8B) was observed in cells incubated with 0.2 U/mL HHIF (Fig 8B, lane 3) and in cells treated with 0.1 FCS (Fig 8B, lane 2) but not in quiescent cells.
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The results obtained in the present work suggest that the endogenous sodium pump inhibitor obtained from hypothalamus (HHIF) is able to inhibit 86Rb uptake by mesangial cells. HHIF was also able to decrease the mesangial cell planar surface area, an event that represents cell contraction.23 Moreover, HHIF increased DNA synthesis, assessed by [3H]thymidine incorporation into DNA, and cell proliferation, measured as the increase in the number of cells per well. As similar effects have been previously reported for ouabain,5 the specific inhibitor of the Na,K-ATPase, it can be suggested that the effects of HHIF are mediated by its ability to inhibit the sodium pump.
HHIF also induced the expression of the immediate early response genes c-fos and c-jun mRNA, an event closely associated with cell proliferation.14 A common mechanism mediating both mesangial cell contraction and proliferation as well as c-fos and c-jun mRNA expression is the increase in [Ca2+]i.24 25 Our data reveal that HHIF induces a slow and sustained increase in [Ca2+]i.
The inhibition of Na,K-ATPase may lead to elevated [Ca2+]i through several possible mechanisms. First, inhibition of the sodium pump may result in slight membrane depolarization26 and consequently increased Ca2+ influx through activated voltage-gated Ca2+ channels.27 This hypothesis is in agreement with our findings pointing to the inhibition of an HHIF-induced increase in [Ca2+]i and cell contraction by the voltage-gated Ca2+ channel blocker verapamil. Okada et al28 and Meyer-Lehnert et al29 have also reported that ouabain induces a sustained increase in [Ca2+]i in VSMCs that can be inhibited by verapamil, suggesting that transmembrane Ca2+ influx through activated voltage-gated Ca2+ channels would play a role in the increase in [Ca2+]i. Our findings are also consistent with those of Goto and colleagues,30 who showed that a digitalis-like factor from human urine enhances 45Ca uptake in VSMCs. However, other studies31 have suggested that partial inhibition of Na,K-ATPase in smooth muscle cells (and presumably in mesangial cells) is unable to induce any substantial degree of cell depolarization.
According to our results, a second hypothesis would be that HHIF might also release calcium from the endoplasmic reticulum. This suggestion is supported by the fact that the inhibition of intracellular calcium release by TMB-8, an endoplasmic calcium release blocker, inhibits HHIF-induced increases in [Ca2+]i and abolishes the cell proliferation and contraction induced by HHIF. It is noteworthy that both blockers, verapamil and TMB-8, significantly inhibit the effect of HHIF on mesangial cells. This could be accounted for by the need for a threshold value in [Ca2+]i to be reached in order for the cells to be activated. The source of this calcium could be either the extracellular medium or the intracellular stores. Therefore, blocker-induced inhibition of calcium mobilization leads to a loss of cellular ability to respond to HHIF. Along this line, it has been recently reported32 that the persistent Ca2+ influx that follows activation of mesangial cells by vasoconstrictors should be attributed to an inward current sensitive to the initial release of internally stored Ca2+. Thus, the inositol 1,4,5-trisphosphate–sensitive Ca2+ pool may serve as a "trigger" for a sustained response, thus initiating a cascade that would amplify the signaling mechanism.
Third, sodium pump inhibition would lead to a rise in cytosolic sodium, a decrease in the transmembrane Na+ gradient, and thus an inhibition of Na+-Ca2+ exchange.30 33 Inhibition of Na+-Ca2+ exchange would induce an increase in [Ca2+]i or an accumulation of Ca2+ in the sarcoplasmic reticulum.31 The presence of Na+-Ca2+ exchange in the plasma membrane of mesangial cells34 35 is consistent with a role of the latter mechanism in an HHIF-induced increase in [Ca2+]i.
Finally, we have recently reported that HHIF is able to inhibit plasma membrane Ca2+-ATPase.12 As this ATPase is involved in the control of [Ca2+]i by pumping out Ca2+ from the cytosol, Ca2+ pump inhibition could also be a mechanism through which HHIF would be able to increase [Ca2+]i. This hypothesis is consistent with the findings of Goto et al30 showing that a digitalis-like factor from human urine inhibits 45Ca efflux in VSMCs.
In summary, the present study demonstrates that a sodium pump inhibitor obtained from bovine hypothalamus and hypophysis (HHIF), which is different from ouabain, induces mesangial cell activation, including contraction and proliferation. These effects seem to be mediated at least in part by an increase in [Ca2+]i. However, the discrepancy in threshold doses for the different effects of HHIF on mesangial cells suggests that the mechanism of action of this substance is highly complex and probably not all the effects observed are mediated exclusively by the increase in [Ca2+]i.
|
Selected Abbreviations and Acronyms |
|---|
|
|
Acknowledgments |
|---|
The present study was partially supported by the "Comisión Interministerial de Investigación Científica y Técnica," Spain (grant SAF 92/0039). We thank Dr Rogelio Gonzalez-Sarmiento for his advice with PCR, Dr José J. García-Marín for his helpful comments on the manuscript, and Nicolas Skinner for his help with the English translation.
Received January 26, 1995; first decision March 14, 1995; accepted August 18, 1995.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Haddy FJ, Pamnani MB, Clough DL. Volume overload hypertension: a defect in the sodium pump? Cardiovasc Rev Rep. 1980;1:376-385.
2. De Wardener HE, MacGregor GA. Dahl's hypothesis that a saluretic substance may be responsible for a sustained rise in arterial pressure: its possible role in essential hypertension. Kidney Int. 1980;18:1-9. [Medline] [Order article via Infotrieve]
3. Poston L, Sewel RB, Wilkinson SP, Richarson PJ, Williams R, Clarkson EM, MacGregor GA, De Wardener HE. Evidence for a circulating sodium transport inhibitor in essential hypertension. Br Med J. 1981;282:847-849.
4. Buckalew VM, Haddy FJ. Circulating natriuretic factor in hypertension. In: Laragh JH, Brenner BM, eds. Hypertension: Pathophysiology, Diagnosis, and Treatment. New York, NY: Raven Press Publishers; 1990:939-954.
5. Montero A, Rodríguez-Barbero A, Ricote M, Sancho J, López-Novoa JM. Effect of ouabain and hypothalamic hypophysary inhibitory factor (HHIF) on rat mesangial cell proliferation. J Cardiovasc Pharmacol. 1993;22(suppl 2):S35-S37.
6.
Hamlyn JM, Blaustein MP, Bova S, DuCharme DW, Harris
DW, Mandel F, Mathews WR, Ludens JH. Identification and
characterization of a ouabain-like compound from human
plasma. Proc Natl Acad Sci U S A. 1991;88:6259-6263.
7.
Mathews WR, DuCharme DW, Hamlyn JM, Harris DW, Mandel
F, Clark MA, Ludens JH. Mass spectral characterization of an
endogenous digitalis-like factor from human
plasma. Hypertension. 1991;17:930-935.
8.
Haupert GT Jr, Sancho JM. Sodium transport
inhibition from bovine hypothalamus. Proc Natl Acad Sci
U S A. 1979;76:4658-4660.
9.
Cantiello HF, Chen E, Ray S, Haupert GT Jr.
Na+ pump in renal tubular cells is regulated by
endogenous Na+-K+-ATPase
inhibitor from hypothalamus. Am J Physiol. 1988;255:F574-F580.
10.
Tymiak AA, Norman JA, Bolgar M, Didonato GC, Lee M,
Parker WL, Lo LC, Bevora N, Nakamishi K, Haber E, Haupert GT.
Physicochemical characterization of an ouabain isomer isolated from
bovine hypothalamus. Proc Natl Acad Sci U S A. 1993;90:8189-8193.
11. Illescas M, Ricote M, Mendez E, Robles RG, Sancho J. Complete purification of two identical Na-pump inhibitors isolated from bovine hypothalamus and hypophysis. FEBS Lett. 1990;261:436-440.[Medline] [Order article via Infotrieve]
12. Sancho JM, Garcia-Martin E, Garcia-Robles R, Santirso R, Villa E, Gutierrez-Merino C, Ricote M. Properties of the purified hypothalamic pituitary Na/K-ATPase inhibitor. J Cardiovasc Pharmacol. 1993;22(suppl 2):S32-S34.
13.
Ricote M, García-Martín E, Sancho J,
Gutiérrez-Merino C. Modulation of the
Ca2+ pump by the hypothalamic hypophysary
inhibitory factor.
Hypertension. 1995;25:365-371.
14. Sukhatme WP, Cao X, Chang LC, Tsai-Morris CH, Stamenkovich D, Ferreira PCP. A zinc-finger-encoding gene regulated with c-fos during growth and differentiation and after cellular depolarisation. Cell. 1988;53:37-43. [Medline] [Order article via Infotrieve]
15. Herschman HR. Extracellular signals, transcriptional responses and cellular specificity. Trends Biochem Sci. 1989;14:455-458. [Medline] [Order article via Infotrieve]
16. Bravo R. Growth factor inducible genes in fibroblasts. In: Habenicht A, ed. Growth Factors. Heidelberg, Germany: Springer; 1990:125-142.
17. Olivera A, Lamas S, Rodriguez-Puyol D, López-Novoa JM. Adenosine induces mesangial cell contraction by an A1-type receptor. Kidney Int. 1989;35:1300-1305. [Medline] [Order article via Infotrieve]
18. Rodriguez-Puyol D, Lamas S, Olivera A, López-Farré A, Ortega G, Hernando L, López-Novoa JM. Actions of cyclosporine A on cultured rat mesangial cells. Kidney Int. 1989;35:632-637. [Medline] [Order article via Infotrieve]
19. Olivera A, López-Novoa JM. Adenosine stimulates Ca2+ fluxes and increases cytosolic free Ca2+ in cultured rat mesangial cells. Biochem J. 1992;282:871-876.
20. Hansen MB, Nielsen SE, Berg K. Re-examination and further development of a precise and rapid dye method for measuring cell growth/cell kill. J Immunol Methods. 1989;119:203-210. [Medline] [Order article via Infotrieve]
21. Favoro J, Treisman R, Kamen R. Transcription of maps of polyoma virus-specific RNA: analysis by two-dimensional nuclease S1 gel mapping. Methods Enzymol. 1980;65:718-749. [Medline] [Order article via Infotrieve]
22.
Saiki RK, Gelfand DM, Stoffel S.
Primer-directed enzymatic amplification of DNA with a thermostable
DNA polymerase. Science. 1988;239:487-491.
23.
Mené P, Simonson S, Dunn MJ. Physiology of
the mesangial cell. Physiol Rev. 1989;69:1347-1424.
24. Simonson MS, Wann S, Mené P, Dubyak GR, Nakazato Y, Sedor JR, Dunn MJ. Endothelin stimulates phospholipase C, Na/H exchange, c-fos expression and mitogenesis in rat mesangial cells. J Clin Invest. 1989;83:708-712.
25.
Mené P, Abboud HE, Dubyak GR, Scarpa A, Dunn
MJ. Effects of PDGF on inositol phosphates,
Ca2+, and contraction of
mesangial cells. Am J Physiol. 1987;253:F458-F463.
26. Mulvany MJ. Changes in sodium pump activity and vascular contraction. J Hypertens. 1985;3:429-436. [Medline] [Order article via Infotrieve]
27. Meyer-Lehnert H, Caramelo C, Tsai P, Schrier RW. Interaction of atriopeptin III and vasopressin on calcium kinetics and contraction of aortic smooth muscle cells. J Clin Invest. 1988;82:1407-1414.
28. Okada K, Caramelo C, Tsai P, Schrier RW. Effect of inhibition of Na/K-adenosine triphosphatase on vascular action of vasopressin. J Clin Invest. 1990;86:1241-1248.
29. Meyer-Lehnert H, Wanning C, Michel H, Bäcker A, Kramer HJ. Cellular mechanisms of action of a ouabain-like factor in vascular smooth-muscle cells. J Cardiovasc Pharmacol. 1993;22:S16-S19.
30.
Goto A, Yamada K, Ishii M, Yoshioka M,
Ishiguro T, Sugimoto T. The effects of urinary
digitalis-like factor on cultured vascular smooth muscle
cells. Hypertension. 1988;11:645-650.
31.
Blaustein MP.
Physiological effects of endogenous
ouabain: control of intracellular Ca2+ stores and
responsiveness. Am J Physiol. 1993;264:C1367-C1383.
32. Mené P, Teti A, Pugliese F, Cinotti, GA. Calcium release-activated calcium influx in cultured human mesangial cells. Kidney Int. 1994;46:122-128. [Medline] [Order article via Infotrieve]
33.
Blaustein MP. Sodium ions, calcium ions,
blood pressure regulation and hypertension: a reassessment and a
hypothesis. Am J Physiol. 1977;232:C165-C177.
34. Mené P, Pugliese F, Cinotti GA. Identification of characteristics of a Na+/Ca2+ exchange in cultured human mesangial cells. Kidney Int. 1990;38:1199-1205. [Medline] [Order article via Infotrieve]
35.
Mené P, Pugliese F, Cinotti GA.
Regulation of Na+/Ca2+ exchange
in cultured human mesangial cells. Am J
Physiol. 1991;261:F466-F473.
This article has been cited by other articles:
 |
|
 |
|
  M. Ricote, E. Garcia-Martin, J. Sancho, and C. Gutierrez-Merino Hypothalamic Hypophyseal Inhibitory Factor (HHIF) Increases Intrasynaptosomal Free Calcium Concentration Hypertension, June 1, 1997; 29(6): 1337 - 1343. [Abstract] [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||