Endothelin, a peptide inhibitor of Na(+)-K(+)-ATPase in intact renaltubular epithelial cells

1989 ◽  
Vol 257 (6) ◽  
pp. C1101-C1107 ◽  
Author(s):  
M. L. Zeidel ◽  
H. R. Brady ◽  
B. C. Kone ◽  
S. R. Gullans ◽  
B. M. Brenner
Keyword(s):  
Initial Rate ◽  
Vascular Endothelial Cells ◽  
Collecting Duct ◽  
Vascular Endothelial ◽  
Na Transport ◽  
Intact Cells ◽  
Medullary Collecting Duct ◽  
Endothelin A ◽  
Potent Vasoconstrictor

Endothelin, a potent vasoconstrictor released by vascular endothelial cells, can induce natriuresis in vivo. These studies examined the regulation of Na+ transport by endothelin in suspensions of rabbit proximal tubule (PT) and inner medullary collecting duct (IMCD) cells. Endothelin reduced oxygen consumption (QO2) by 18 +/- 1% in IMCD cells but did not alter QO2 in PT cells. In IMCD cells, endothelin inhibited QO2 half maximally at approximately 5 x 10(-12) M. Several lines of evidence indicate that endothelin reduces QO2 by inhibiting the Na(+)-K(+)-ATPase. 1) Endothelin gave no further inhibition of QO2 after ouabain and blunted the stimulatory effect of amphotericin B on QO2 (+29 +/- 4% in absence of endothelin, 0 +/- 5% in presence of endothelin; n = 6 preparations, P less than 0.001). 2) Endothelin inhibited ouabain-sensitive 86Rb+ uptake by 46.6 +/- 8.6% at 10 s and by 35.4 +/- 5.3% at 30 s without altering uptake at 60 min. 3) Addition of endothelin to IMCD cells induced a net K+ efflux with an initial rate of 32.2 +/- 4.8 nmol.min-1.mg protein-1, consistent with inhibition of the Na(+)-K(+)-ATPase. In contrast to the response observed in intact cells, in permeabilized IMCD cells endothelin did not inhibit ouabain-sensitive ATPase. Several observations indicated that prostaglandin E2 (PGE2) mediates endothelin inhibition of Na(+)-K(+)-ATPase activity. 1) The response to endothelin was blocked by ibuprofen in assays of QO2, net K+ flux, and 86Rb+ uptake. 2) Endothelin and PGE2 gave equivalent, nonadditive inhibition of ouabain-sensitive 86Rb+ uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinins inhibit conductive Na+ uptake by rabbit inner medullary collecting duct cells

1990 ◽  
Vol 258 (6) ◽  
pp. F1584-F1591 ◽  
Author(s):  
M. L. Zeidel ◽  
K. Jabs ◽  
D. Kikeri ◽  
P. Silva
Keyword(s):  
Initial Rate ◽  
Collecting Duct ◽  
Physiological Effect ◽  
Na Transport ◽  
Inner Medullary Collecting Duct ◽  
Transport Effects ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Na Uptake

Kinins promote natriuresis in vivo, at least in part by altering Na+ transport in the collecting duct. Using freshly prepared suspensions of rabbit inner medullary collecting duct (IMCD) cells, we have examined the effects of kinins on Na+ transport using measurements of oxygen consumption (QO2) and isotopic Na+ uptake. Bradykinin (BK) inhibited IMCD cell QO2 by 24.7 +/- 0.9% without significantly reducing QO2 in cells derived from the outer medullary collecting duct. BK and kallidin half-maximally inhibited QO2 at concentrations in the 10(-12)-10-(-11) M range; beta 1-receptor agonists did not alter QO2, and beta 1-receptor antagonism did not reduce the effect of kinins. These observations indicate that the actions of kinins on IMCD cells are mediated by beta 2-receptors or a distinct subclass. Several observations indicate that kinins reduce QO2 by inhibiting Na+ entry: in the absence of Na+, BK did not reduce QO2; BK inhibition of QO2 was not additive with ouabain, amiloride, atrial natriuretic peptide (ANP), or 8-bromoguanosine 3',5'-cyclic monophosphate and was abolished in the presence of the cation ionophore amphotericin B. Measurements of isotopic Na+ uptake demonstrated that BK reduced the initial rate of Na+ entry by 58%; BK inhibited the amiloride-sensitive component of conductive Na+ uptake. Because ANP inhibits conductive Na+ entry in IMCD cells via stimulation of cGMP accumulation, the effect of BK on cGMP levels was determined. Unlike ANP, BK did not increase cGMP levels, indicating that transport effects of kinins in IMCD are not mediated by cGMP. Thus kinins directly inhibit conductive Na+ entry in IMCD cells at concentrations suggestive of a physiological effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of resistance to mineralocorticoid hormone in cultured inner medullary collecting duct cells by TGF-beta 1

1994 ◽  
Vol 267 (5) ◽  
pp. F767-F775 ◽  
Author(s):  
R. F. Husted ◽  
K. Matsushita ◽  
J. B. Stokes
Keyword(s):  
Transforming Growth Factor ◽  
Collecting Duct ◽  
Tgf Beta ◽  
Na Transport ◽  
Dependent Inhibition ◽  
Subsequent Exposure ◽  
Medullary Collecting Duct ◽  
Induction Of Resistance ◽  
Mineralocorticoid Hormone

The renal collecting duct is a major target for the mineralocorticoid hormone aldosterone which acts to enhance electrogenic Na+ absorption. The cortical portion of the collecting duct displays a vigorous response to mineralocorticoids administered in vivo. The terminal, or inner medullary portion, does not usually display such a vigorous response; the reason for this difference is unknown. To explore one possible mechanism for this lack of response, we varied the conditions of culturing these cells and determined that serum inhibited the ability of aldosterone to enhance Na+ transport. By screening 11 peptides, we found that transforming growth factor (TGF)-beta 1 produced a concentration-dependent inhibition of the action of aldosterone. The action of TGF-beta 1 required at least several hours of incubation. Resistance to the action of aldosterone could be produced by preincubating the monolayers with TGF-beta 1 for a few hours; subsequent exposure to aldosterone for up to 48 h failed to stimulate Na+ transport. TGF-beta 1 did not produce a change in cell morphology or the content of DNA, ATP, or ADP; there was a small reduction in protein content. Pretreatment with cycloheximide failed to reproduce the TGF-beta 1 effect. The induction of resistance to mineralocorticoid hormone may play an important role in modulating the effects of aldosterone on Na+ homeostasis.

scholarly journals Synthesis and physiological activity of heterodimers comprising different splice forms of vascular endothelial growth factor and placenta growth factor

1996 ◽  
Vol 316 (3) ◽  
pp. 703-707 ◽  
Author(s):  
Ralf BIRKENHÄGER ◽  
Bernard SCHNEPPE ◽  
Wolfgang RÖCKL ◽  
Jörg WILTING ◽  
Herbert A. WEICH ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Vascular Endothelial Cells ◽  
Physiological Activity ◽  
Expression System ◽  
Vascular Endothelial ◽  
Placenta Growth Factor ◽  
Splice Forms

Vascular endothilial growth factor (VEGF) and placenta growth factor (PIGF) are members of a dimeric-growth-factor family with angiogenic properties. VEGF is a highly potent and specific mitogen for endothelial cells, playing a vital role in angiogenesis in vivo. The role of PIGF is less clear. We expressed the monomeric splice forms VEGF-165, VEGF-121, PIGF-1 and PlGF-2 as unfused genes in Escherichia coli using the pCYTEXP expression system. In vitro dimerization experiments revealed that both homo- and hetero-dimers can be formed from these monomeric proteins. The dimers were tested for their ability to promote capillary growth in vivo and stimulate DNA synthesis in cultured human vascular endothelial cells. Heterodimers comprising different VEGF splice forms, or combinations of VEGF/PlGF splice forms, showed mitogenic activity. The results demonstrate that four different heterodimeric growth factors are likely to have as yet uncharacterized functions in vivo.

Angiopoietin-related growth factor (AGF) promotes angiogenesis

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3760-3765 ◽  
Author(s):  
Yuichi Oike ◽  
Yasuhiro Ito ◽  
Hiromitsu Maekawa ◽  
Tohru Morisada ◽  
Yoshiaki Kubota ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transgenic Mice ◽  
Vascular Endothelial Cells ◽  
Direct Injection ◽  
Angiogenic Factor ◽  
Epidermal Keratinocytes ◽  
Vascular Endothelial ◽  
Novel Therapeutic Strategies

Abstract We report here the identification of angiopoietin-related growth factor (AGF) as a positive mediator for angiogenesis. To investigate the biologic function of AGF in angiogenesis, we analyzed the vasculature in the dermis of transgenic mice expressing AGF in mouse epidermal keratinocytes (K14-AGF). K14-AGF transgenic mice were grossly red, especially in the ears and snout, suggesting that hypervascularization had occurred in their skin. Histologic examination of ear skin from K14-AGF transgenic mice revealed increased numbers of microvessels in the dermis, whereas the expression of several angiogenic factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGFs), and angiopoietin-1 (Ang-1), was decreased. We showed that AGF is a secreted protein and does not bind to tyrosine kinase with immunoglobulin and EGF-homology domain (Tie1) or Tie2 receptors. An in vitro chamber assay revealed that AGF directly promotes chemotactic activity of vascular endothelial cells. Both mouse corneal and matrigel plug assays showed that AGF induces neovascularization in vivo. Furthermore, we found that plasma leakage occurred after direct injection of AGF into the mouse dermis, suggesting that AGF directly induces a permeability change in the local vasculature. On the basis of these observations, we propose that AGF is a novel angiogenic factor and that handling of its biologic functions could lead to novel therapeutic strategies for control of angiogenesis.

Interaction between vascular endothelial cells and vascular intimal spindle-shaped cells in vitro

1983 ◽  
Vol 60 (1) ◽  
pp. 89-102
Author(s):  
D de Bono ◽  
C. Green
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Three Dimensional ◽  
Vascular Endothelial ◽  
Pure Cultures ◽  
Species Specific ◽  
Endothelial Growth Factor

The interactions between human or bovine vascular endothelial cells and fibroblast-like vascular intimal spindle-shaped cells have been studied in vitro, using species-specific antibodies to identify the different components in mixed cultures. Pure cultures of endothelial cells grow as uniform, nonoverlapping monolayers, but this growth pattern is lost after the addition of spindle cells, probably because the extracellular matrix secreted by the latter causes the endothelial cells to modify the way they are attached to the substrate. The result is a network of tubular aggregates of endothelial cells in a three-dimensional ‘polylayer’ of spindle-shaped cells. On the other hand, endothelial cells added to growth-inhibited cultures of spindle-shaped cells will grow in sheets over the surface of the culture. Human endothelial cells grown in contact with spindle-shaped cells have a reduced requirement for a brain-derived endothelial growth factor. The interactions of endothelial cells and other connective tissue cells in vitro may be relevant to the mechanisms of endothelial growth and blood vessel formation in vivo, and emphasize the potential importance of extracellular matrix in controlling endothelial cell behaviour.

Urodilatin: binding properties and stimulation of cGMP generation in rat kidney cells

1993 ◽  
Vol 264 (2) ◽  
pp. F267-F273
Author(s):  
H. Saxenhofer ◽  
W. R. Fitzgibbon ◽  
R. V. Paul
Keyword(s):  
Guanylate Cyclase ◽  
Mesangial Cells ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Binding Characteristics ◽  
Papillary Collecting Duct ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Anp Receptors

Urodilatin (URO) [ANP-(95-126)] is an analogue of atrial natriuretic peptide (alpha-ANP) [ANP-(99-126)] that was first isolated from human urine. In rat mesangial cells, URO competed with high affinity for non-guanylate cyclase-coupled ANPR-C receptors [concentration at which 50% labeled ligand is displaced (IC50) approximately 70 pM], but with lesser affinity to the guanylate cyclase-linked ANPR-A receptors (IC50 approximately 800 pM). alpha-ANP bound to both receptors with similar affinity [dissociation constant (Kd) approximately 150 pM]. In papillary collecting duct homogenates, which possess only ANPR-A receptors, the apparent Kd value averaged 229 pM for alpha-ANP and 2.7 nM for URO. Intravenous URO was at least as potent and effective as alpha-ANP in inducing diuresis and natriuresis in anesthetized rats, but URO was approximately 10-fold less potent in stimulating guanosine 3',5'-cyclic monophosphate generation in mesangial and inner medullary collecting duct cells. We conclude that URO has a lesser affinity than alpha-ANP for guanylate cyclase-coupled ANP receptors in the kidney and that the relative natriuretic potency of URO in vivo cannot be directly attributed to its binding characteristics with ANPR-A receptors.

Endopeptidases 3.4.24.15 and 24.16 in endothelial cells: potential role in vasoactive peptide metabolism

2003 ◽  
Vol 284 (6) ◽  
pp. H1978-H1984 ◽  
Author(s):  
M. Ursula Norman ◽  
Shane B. Reeve ◽  
Vincent Dive ◽  
A. Ian Smith ◽  
Rebecca A. Lew
Keyword(s):  
Endothelial Cells ◽  
High Performance ◽  
Vascular Endothelial Cells ◽  
Umbilical Vein ◽  
Hybrid Cell ◽  
Fluorescent Substrate ◽  
Intact Cells ◽  
Aortic Endothelial Cells

The closely related metalloendopeptidases EC 3.4.24.15 (EP24.15; thimet oligopeptidase) and 24.16 (EP24.16; neurolysin) cleave a number of vasoactive peptides such as bradykinin and neurotensin in vitro. We have previously shown that hypotensive responses to bradykinin are potentiated by an inhibitor of EP24.15 and EP24.16 (26), suggesting a role for one or both enzymes in bradykinin metabolism in vivo. In this study, we have used selective inhibitors that can distinguish between EP24.15 and EP24.16 to determine their activity in cultured endothelial cells (the transformed human umbilical vein endothelial hybrid cell line EA.hy926 or ovine aortic endothelial cells). Endopeptidase activity was assessed using a specific quenched fluorescent substrate [7-methoxycoumarin-4-acetyl-Pro-Leu-Gly-d-Lys(2,4-dinitrophenyl)], as well as the peptide substrates bradykinin and neurotensin (assessed by high-performance liquid chromatography with mass spectroscopic detection). Our results indicate that both peptidases are present in endothelial cells; however, EP24.16 contributes significantly more to substrate cleavage by both cytosolic and membrane preparations, as well as intact cells, than EP24.15. These findings, when coupled with previous observations in vivo, suggest that EP24.16 activity in vascular endothelial cells may play an important role in the degradation of bradykinin and/or other peptides in the circulation.

Apical and basolateral membrane H+ extrusion mechanisms in inner stripe of rabbit outer medullary collecting duct

1990 ◽  
Vol 259 (4) ◽  
pp. F628-F635 ◽  
Author(s):  
S. R. Hays ◽  
R. J. Alpern
Keyword(s):  
Initial Rate ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Control Level ◽  
Atpase Inhibitor ◽  
Initial Control ◽  
Acid Load ◽  
Extrusion Mechanism ◽  
Medullary Collecting Duct

To examine mechanisms of H+ extrusion in the inner stripe of outer medullary collecting duct (OMCDIS), cell pH (pHi) was measured microfluorometrically in in vitro perfused tubules by use of 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. In total absence of luminal and peritubular Na+, pHi recovery from an acid load (NH3/NH+4 pulse) occurred at an initial rate of 0.13 +/- 0.02 pH units/min, whereas in the presence of 135 mM peritubular Na+, pHi recovered at 1.40 +/- 0.28 pH units/min. Na(+)-dependent pHi recovery was completely inhibited by 1.0 mM peritubular amiloride. Luminal Na+ (135 mM) addition had no effect on pHi recovery. Na(+)-independent pHi recovery from acid load was manifest by a triphasic response: 1) initial slow alkalinization; 2) slow cell acidification; and 3) a final phase that exhibited gradually increasing rates of alkalinization, returning pHi above the initial control level (pre-NH3/NH+4 pulse). Luminal N-ethylmaleimide (NEM, 500 microM), an H(+)-ATPase inhibitor, significantly inhibited initial rate of pHi recovery and total pHi recovery; whereas 500 microM peritubular NEM had no effect on initial rate of pHi recovery. Luminal SCH 28080 (100 microM), an H(+)-K(+)-ATPase inhibitor, had no effect on initial rate of pHi recovery or total pHi recovery. Thus rabbit OMCDIS possesses both an apical membrane NEM-sensitive, SCH 28080-insensitive, Na(+)-independent H+ extrusion mechanism (likely a simple H(+)-translocating ATPase) and a basolateral membrane amiloride-sensitive Na(+)-H+ antiporter.

EDRF as a possible mediator of sepsis-induced arteriolar dilation in skeletal muscle

1992 ◽  
Vol 262 (3) ◽  
pp. H880-H887 ◽  
Author(s):  
A. S. Lubbe ◽  
R. N. Garrison ◽  
H. M. Cryer ◽  
N. L. Alsip ◽  
P. D. Harris
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Output ◽  
Defense Mechanisms ◽  
Vascular Endothelial Cells ◽  
Early Period ◽  
Vascular Endothelial ◽  
Low Cardiac Output ◽  
E Coli

Vascular endothelial cells influence microvessel diameters in vivo and in vitro and participate in host-defense mechanisms during sepsis. We examined whether small arteriole dilation in skeletal muscle during high cardiac output bacteremia (HOB) and low cardiac output live Escherichia coli sepsis (LOS) is mediated by an endothelium-derived relaxing factor (EDRF). Local chemical blockade of EDRF by hydroquinone (HQ) substantially blunted acetylcholine-induced dilation of small arterioles. HQ also prevented large arteriole (55-135 microns) constriction and small arteriole (6-22 microns) dilation in the cremaster muscle of rats during HOB. In LOS, small arteriole dilation was also prevented by HQ but only during the early period when blood pressure was unchanged from baseline. HQ did not alter large arteriole constriction during LOS. We conclude that small arteriole vasodilation in skeletal muscle is mediated at least in part by EDRF during bacteremia. Because EDRF cannot mediate large arteriole constriction and because HQ blunted large arteriole constriction during HOB, we now suspect that HQ also interferes at least in part with some large arteriole vasoconstrictor mechanism, possibly leukotrienes or an endothelium-derived constricting factor, which mediates large arteriole constriction during HOB. Our data also suggest that large arteriole constriction during LOS is partly mediated by factors that are unaffected by HQ. The endothelium appears to play an important role in the microcirculatory responses of skeletal muscle to live E. coli sepsis through more than one mechanism.

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