Parathyroid hormone inhibits proximal tubule Na(+)-K(+)-ATPase activity

1992 ◽  
Vol 262 (2) ◽  
pp. F209-F216 ◽  
Author(s):  
C. P. Ribeiro ◽  
L. J. Mandel
Keyword(s):  
Atpase Activity ◽  
Proximal Tubule ◽  
Transepithelial Transport ◽  
Mitochondrial Activity ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Camp Generation ◽  
Dependent Inhibition ◽  
Camp Formation

arathyroid hormone (PTH) decreases the transepithelial transport of Na+ in the proximal tubule, an action ascribed to PTH-inhibited apical Na(+)-H+ exchanger-dependent Na+ entry. We tested the possibility that PTH could also diminish Na(+)-K(+)-ATPase-dependent Na+ exit. To dissociate effects on Na+ entry, studies were performed in a suspension of rat proximal tubules by measuring nystatin-stimulated ouabain-inhibitable O2 consumption (QO2) and monensin-stimulated ouabain-sensitive 86Rb uptake in the absence or presence of bovine PTH-(1-34) fragment. PTH inhibited the percent nystatin-stimulated QO2 in a concentration-dependent manner, with maximal effect at 10(-10) M. PTH-increased cAMP formation was seen at doses higher than 10(-9) M and was maximal at 10(-7) M. Dibutyryl cAMP (10(-4) M) only partially reproduced the PTH action on QO2. Angiotensin II (10(-6) M) blunted the effect of 10(-7) M PTH on QO2, although it did not change 10(-7) M PTH-dependent cAMP generation. The analogues PTH-(3-34) and [Nle8,Nle18,Tyr34]PTH-(3-34)-amide mimicked the effects of PTH-(1-34) on QO2 but did not affect cAMP formation. Monensin-stimulated ouabain-sensitive 86Rb uptake was inhibited by PTH in a dose-dependent manner, with 10(-7) M PTH being maximally inhibitory. Na(+)-K(+)-ATPase activity was also decreased by PTH-(3-34) in a concentration-dependent manner, with maximal effect occurring at 10(-8) M. Agonist-dependent inhibition of Na+ pump was not due to a decrease of mitochondrial activity, because mitochondrial uncoupled QO2 rates were the same in control and PTH-treated tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine A1 receptor-mediated inhibition of vasopressin action in inner medullary collecting duct

1994 ◽  
Vol 266 (5) ◽  
pp. F791-F796 ◽  
Author(s):  
R. M. Edwards ◽  
W. S. Spielman
Keyword(s):  
Receptor Agonist ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Camp Accumulation ◽  
Concentration Dependent Manner ◽  
Cgs 21680 ◽  
Camp Generation ◽  
A1 Receptor

We examined the effects of adenosine and adenosine analogues on arginine vasopressin (AVP)-induced increases in osmotic water permeability (Pf; micron/s) and adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in rat inner medullary collecting ducts (IMCDs). When added to the bath, the A1 receptor agonist N6-cyclohexyladenosine (CHA) produced a rapid and reversible inhibition of AVP-stimulated (10 pM) Pf (1,781 +/- 195 to 314 +/- 85 microns/s at 0.3 microM CHA; n = 9). The inhibitory effect of CHA was concentration dependent, with a 50% inhibitory concentration of 10 nM. The effect of CHA was inhibited by prior exposure of IMCDs to the A1 receptor antagonist 1,3-dipropylxanthine-8-cyclopentylxanthine (DP-CPX; 1 microM) or by preincubation with pertussis toxin. CHA had no effect on cAMP-induced increases in Pf. In addition to CHA, adenosine and the nonselective agonist 5'-(N-ethylcarboxamido)-adenosine (NECA) inhibited AVP-dependent Pf by > or = 70%, whereas the A2 receptor agonist CGS-21680 had no effect. Luminal adenosine (0.1 mM) had no effect on basal or AVP-stimulated Pf. CHA, NECA, and adenosine but not CGS-21680 inhibited AVP-stimulated cAMP accumulation in a concentration-dependent manner (50% inhibitory concentrations 0.1–300 nM). The inhibitory effect of CHA on AVP-stimulated cAMP accumulation was attenuated by DPCPX. We conclude that adenosine, acting at the basolateral membrane, inhibits AVP action in the IMCD via interaction with A1 receptors. The inhibition occurs proximal to cAMP generation and likely involves an inhibitory G protein.

Succinate alters respiration, membrane potential, and intracellular K+ in proximal tubule

1988 ◽  
Vol 255 (6) ◽  
pp. F1170-F1177 ◽  
Author(s):  
S. R. Gullans ◽  
B. C. Kone ◽  
M. J. Avison ◽  
G. Giebisch
Keyword(s):  
Membrane Potential ◽  
Atpase Activity ◽  
Ion Transport ◽  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Coupling Efficiency ◽  
Atp Synthesis ◽  
Dependent Manner ◽  
Kinetic Evaluation ◽  
Apparent Increase

Succinate, a dicarboxylic acid, is an intermediate in the Krebs cycle that is transported and metabolized by the renal proximal tubule. It is also known to increase proximal tubule transport of phosphate and glucose but not fluid by unknown mechanisms. In the present study, succinate increased proximal tubule respiration in a dose-dependent manner, and a kinetic evaluation indicated that two separate processes were activated. A lower-affinity (Km = 0.9 mM), higher-capacity stimulation (Vmax increase of 49%) was attributed to a decrease in the mitochondrial coupling efficiency. A higher-affinity process (Km = 0.012 mM) was related to an apparent increase in ATP synthesis. The apparent increase in ATP synthesis was not associated with a change in Na+-K+-ATPase activity, however, but rather indicated a 49% increase in ion transport-independent ATP utilization. Basolateral membrane potential hyperpolarized by -7 mV in the presence of succinate, and this was related to an increase in the K+ transference number. Finally, 1 and 5 mM succinate promoted a net cellular uptake of K+, leading to an 11% increase in intracellular K+, which was not the result of an increase in Na+-K+-ATPase activity. Thus the cellular entry and metabolism of succinate promotes multiple changes in ion transport without altering Na+-K+-ATPase activity.

Effects of extracellular ATP on ICa, [Ca2+]i, and contraction in isolated ferret ventricular myocytes

1993 ◽  
Vol 264 (3) ◽  
pp. C702-C708 ◽  
Author(s):  
Y. Qu ◽  
H. M. Himmel ◽  
D. L. Campbell ◽  
H. C. Strauss
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Ventricular Myocardium ◽  
Inhibitory Effect ◽  
Extracellular Atp ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
The Right

The effects of extracellular ATP on the voltage-activated "L-type" Ca current (ICa), action potential, resting and transient intracellular Ca2+ levels, and cell contraction were examined in enzymatically isolated myocytes from the right ventricles of ferrets. With the use of the whole cell patch-clamp technique, extracellular ATP (10(-7) to 10(-3) M) inhibited ICa in a time- and concentration-dependent manner. ATP decreased the peak amplitude of ICa without altering the residual current at the end of 500-ms clamp steps. The concentration-response relationship for ATP inhibition of ICa was well described by a conventional Michaelis-Menten relationship with a half-maximal inhibitory concentration of 1 microM and a maximal effect of 50%. Consistent with its inhibitory effect on ICa, ATP hyperpolarized the plateau phase and shortened the action potential duration. In fura-2-loaded myocytes, extracellular ATP did not change the resting myoplasmic Ca2+ levels; however, when current was elicited under voltage-clamp conditions, ATP both decreased the myoplasmic intracellular Ca2+ transient and inhibited the degree of cell shortening. Our results suggest that ATP could be a genuine and potent extracellular modulator of cardiac function in ferret ventricular myocardium.

Inhibitory action of somatostatin-14 on hormone-stimulated cyclic adenosine monophosphate induction in porcine granulosa and luteal cells

1992 ◽  
Vol 134 (2) ◽  
pp. 297-306 ◽  
Author(s):  
K. Rajkumar ◽  
D. E. Kerr ◽  
R. N. Kirkwood ◽  
B. Laarveld
Keyword(s):  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Luteal Cells ◽  
Camp Generation ◽  
Camp Induction ◽  
Camp Levels ◽  
Somatostatin 14

ABSTRACT Somatostatin-14 (SRIF-14) inhibited, in a concentration-dependent manner, LH- and forskolin-stimulated cyclic adenosine monophosphate (cAMP) induction in porcine granulosa and luteal cells. The inhibitory effect of SRIF-14 on hormone-induced cAMP generation was more potent in porcine ovarian cells than in the GH-3 pituitary cell line. The inhibitory effect of SRIF-14 was impeded by neutralizing its biological activity with specific antiserum. Preincubation of luteal and granulosa cells with phorbol 12-myristate 13-acetate (PMA) enhanced LH- and forskolin-stimulated cAMP levels. SRIF-14 failed to inhibit LH- or forskolin-stimulated cAMP levels in cells preincubated with PMA. It is concluded that SRIF-14 inhibits hormone-stimulated cAMP induction in the porcine ovary. LH-induced protein kinase C activation may be physiologically important to alleviate the inhibitory effects of SRIF-14. Journal of Endocrinology (1992) 134, 297–306

The Role of β2-Glycoprotein I in the Clearance of Platelet Microvesicles.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 145-145
Author(s):  
Hanan Abdel-Monem ◽  
Swapan Kumar Dasgupta ◽  
Anhquyen Le ◽  
Anthony Prakasam ◽  
Perumal Thiagarajan
Keyword(s):  
Plasma Proteins ◽  
Plasma Concentrations ◽  
Major Protein ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Anionic Phospholipid ◽  
Concentration Dependent Manner ◽  
Glycoprotein I

Abstract Abstract 145 The physiological function of β2-glycoprotein I is unclear and several studies suggest a role in the clearance of anionic phospholipid containing membranes. Anionic phospholipid containing liposomes are cleared rapidly from the circulation by the reticuloendothelial cells. In rats, uptake of liposomes by Kupffer cells requires that the liposomes bind to plasma proteins. In mice, the clearance of liposomes from the circulation is related to their ability to interact with plasma proteins. β2-glycoprotein I was identified as a major protein associated with rapid clearance of liposomes and pretreating the mice with antiβ2- glycoprotein I antibodies was found to significantly increase the half-life of the liposome. In vitro, β2-glycoprotein I was also shown to promote the phagocytosis of phosphatidylserine containing liposomes and apoptotic tumor cells. In conditions associated with increased microvesicles generation such as disseminated intravascular coagulation, plasma levels of β;2-glycoprotein I was reduced presumably due to its consumption. Antibodies to β2 glycoprotein I are frequently seen in patients with systemic lupus erythematosus and at times, in otherwise normal individuals. A subset of these antibodies prevents the assembly of the prothrombinase and the tenase complexes on phospholipid membrane, leading to the lupus anticoagulant effect. The presence of these antibodies is clinically very significant, as individuals harboring these antibodies are at risk for thromboembolic manifestations. We studied the role of β-glycoprotein I in the clearance of procoagulant platelet microvesicles and the effect of the auto antibodies in the phagocytosis of platelet microvesicles. We labeled β2-glycoprotein I with BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-hydrazide and β2-glycoprotein I incorporated 1.8 mole of BODIPY /mole. Labeling of β2-glycoprotein I with BODIPY did not change the binding efficacy of β2-glycoprotein I to cardiolipin as determined by Elisa assay. Binding of BODIPY-β2-glycoprotein I to platelet microvesicles was analyzed by flow cytometry. BODIPY- β2-glycoprotein I bound to phosphatidylserine-expressing platelet microvesicles in a concentration-dependent manner. Binding was inhibited by 50 fold molar excess of unlabeled β2-glycoprotein I, annexin A5 and the phosphatidylserine-binding C1C2 fragment of lactadherin. β2-glycoprotein I also promoted the phagocytosis of platelet microvesicles by THP-1 derived macrophages in vitro at physiological plasma concentrations with a half maximal effect at ∼10 ug/ml. β2-glycoprotein I-mediated phagocytosis was inhibited by annexin V and the C1C2 fragment of lactadherin. Furthermore, immunoaffinity purified β2-glycoprotein I-dependent antiphospholipid antibodies from 5 patients inhibited the phagocytosis in a concentration dependent manner. These studies suggest β2-glycoprotein I binding to phosphatidylserine-expressing procoagulant platelet microvesicles promotes their clearance by macrophages and autoantibodies to β2-glycoprotein I inhibit the process. The predictive value of antiβ-2 glycoprotein I for thrombosis is highly variable but the correlation is stronger in patients with lupus. In lupus, there is impaired clearance of procoagulant apoptotic cells. β2-glycoprotein I may have a significant role in their clearance and antibodies to β2-glycoprotein I may causally related to the thrombosis in these patients by inhibiting the clearance. Disclosures: No relevant conflicts of interest to declare.

Phagocytosis of platelet microvesicles and β2– glycoprotein I

2010 ◽  
Vol 104 (08) ◽  
pp. 335-341 ◽  
Author(s):  
Anhquyen Le ◽  
Anthony Prakasam ◽  
Hanan Abdel-Monem ◽  
Swapan Dasgupta ◽  
Perumal Thiagarajan
Keyword(s):  
Antiphospholipid Syndrome ◽  
Antiphospholipid Antibodies ◽  
Binding Capacity ◽  
Plasma Concentrations ◽  
Physiological Role ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phospholipid Binding ◽  
Glycoprotein I

SummaryThe majority of the antiphospholipid antibodies, present in patients with antiphospholipid syndrome, are directed against conformational epitopes in β2-glycoprotein I. β2-glycoprotein I is an anionic phospholipid- binding 50-kDa plasma protein whose physiological role is not clear. Here we investigate the role of β2-glycoprotein I in the phagocytosis of phosphatidylserine-expressing platelet microvesicles and the effect of autoantibodies to β2-glycoprotein I on this process. We labelled the glycans of β2-glycoprotein I with BODIPY (4,4-difluoro- 4-bora-3a,4a-diaza-s-indacene)-hydrazide without affecting its phospholipid binding capacity. BODIPY-β2-glycoprotein I bound to platelet microvesicles in a concentration-dependent manner and promoted the phagocytosis of platelet microvesicles by THP-1 derived macrophages in vitro at physiological plasma concentrations with a half maximal effect at ∼10 μg/ml. β2-glycoprotein I-stimulated phagocytosis was inhibited by annexin A5 and the phosphatidylserine-binding C1C2 fragment of lactadherin. Furthermore, immunoaffinity purified β2-glycoprotein I-dependent antiphospholipid antibodies from five patients with antiphospholipid syndrome inhibited the phagocytosis in a concentration- dependent manner. These studies suggest that the binding of β2-glycoprotein I to phosphatidylserine-expressing procoagulant platelet microvesicles may promote their clearance by phagocytosis and autoantibodies to β2-glycoprotein I may inhibit this process to induce a procoagulant state.

Differential inhibition of inflammatory cytokine release from cultured alveolar macrophages from smokers and non smokers by No2

1997 ◽  
Vol 16 (10) ◽  
pp. 577-588 ◽  
Author(s):  
Tiziana Dandrea ◽  
Ba Tu ◽  
Anders Blomberg ◽  
Thomas Sandström ◽  
Magnus Sköld ◽  
...  
Keyword(s):  
Steady State ◽  
Alveolar Macrophages ◽  
Exposure Model ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Tnf Α ◽  
Dependent Inhibition ◽  
Steady State Levels ◽  
Dose Dependent

Human alveolar macrophages (AMs) obtained from smokers and non-smokers by bronchoalveolar lavage (BAL) were subjected to various concentrations of NO2 in an inverted monolayer exposure model. Culture super natants were collected 4 h after the exposure and assayed for secreted TNF-α, IL-1β, IL-8 and MIP-1α. The steady state levels of the mRNAs for these cytokines were also analysed in the cells. The adherence of BAL cells to plastic prior to exposure to the gas elevated the steady state mRNA levels of all four cytokines tested in smoker's cells and that of TNF-α and IL-1β, but not IL-8 (MIP-1α not tested), in non-smoker's cells. Interestingly, adherent cells from non-smokers released circa 15-, 3-,1.5- and 3-fold the amounts of IL-1β, IL-8, TNF-α and MIP-1α, respectively, than smoker's cells during control incubation or exposure to air. A 20 min exposure to NO2 (5 or 20 p.p.m.) did not increase the secretion of any of the cytokines from either cell type. In contrast, NO2 caused a concentration- dependent inhibition of the secretion of all cytokines except IL-1β from smoker's cells. Additionally, NO2 greatly diminished the release of all cytokines in response to further treatment with lipopolysaccharide (LPS). In contrast, only the secretion of TNF-α from non-smoker's cells was inhibited by the gas in a concentration- dependent manner, whilst LPS-induced secretion of the cytokines was not affected by the gas. The steady state levels of the respective mRNAs for each of the cytokines were not significantly affected in smoker's cells by exposure to NO2, except for a negative, dose-dependent trend in the case of TNF-α. Nitrogen dioxide also failed to elevate the levels of the mRNAs in non-smoker's cells but, again, tended to diminish the levels, particularly of IL-1β mRNA. However, exposure to the gas inhibited LPS- induced accumulation of cytokine mRNAs in smoker's cells only. The data suggest that macrophage-derived cytokine mediators of the sepsis response may not play a role in the generation of NO2-induced inflammation in the human lung. Conversely, the gas seems to non-specifically inhibit the release and/or production of cytokines, particularly from smoker's cells, at the post-transcrip tional level, and impairs the ability of the cells to increase the transcription and release of the cytokines in response to bacterial LPS. The fact that NO2 seriously impaired the already diminished capacity of smoker's cells to release several important pro-inflammatory cytokines, both under control conditions and in response to LPS, strongly suggest that the inhalation of NO2 in cigarette smoke may contribute to impairing host defence against infection in the lung.

scholarly journals Stimulation of plasmin activity by oleic acid

1992 ◽  
Vol 282 (3) ◽  
pp. 863-866 ◽  
Author(s):  
A A R Higazi ◽  
Z Finci-Yeheskel ◽  
A A R Samara ◽  
R Aziza ◽  
M Mayer
Keyword(s):  
Oleic Acid ◽  
Binding Sites ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Plasmin Activity ◽  
Concentration Dependent Manner ◽  
Acid Analogue ◽  
Kinetic Pattern ◽  
Fold Stimulation ◽  
Stimulation Of

The amidolytic activity of plasmin with the chromogenic substrate H-D-valyl-L-leucyl-L-lysine p-nitroanilide (S-2251) is stimulated by oleic acid in a dose-dependent and saturable fashion. The activity of plasmin on S-2251 in the presence of oleic acid followed a sigmoidal kinetic pattern, with an almost 4-fold stimulation of activity at 60 microM-oleic acid. Half-maximal stimulation occurred at an oleic acid level of 19.5 microM. The amino acid analogue 6-aminohexanoic acid (AHA), which is known to bind to lysine-binding sites in plasmin, suppressed the stimulatory effect of oleic acid in a concentration-dependent manner; at 0.3 mM-AHA, about 70% of the oleic acid-dependent enhancement of plasmin activity was abolished. The l/v versus 1/[S] plot for plasmin changed in the presence of oleic acid from a linear to a non-linear curve, suggesting positive co-operativity. 14C-labelled oleic acid bound to plasmin, and the bound ligand was displaced by an excess of unlabelled oleic acid. Oleic acid also produced a marked (40-fold) stimulation of the plasminogen-dependent cleavage of S-2251 by urokinase. A half-maximal effect on plasminogen activation was obtained at 40 microM-oleic acid. The present findings suggest that the ability of oleic acid to stimulate plasmin activity and to enhance the conversion of plasminogen to plasmin depends on the interaction of oleic acid with specific lysine-binding sites in plasmin.

Comparable vasorelaxant effects of 17α- and 17β-oestradiol on rat mesenteric resistance arteries: an action independent of the oestrogen receptor

1999 ◽  
Vol 97 (6) ◽  
pp. 649-655 ◽  
Author(s):  
Ebrahim K. NADERALI ◽  
Adrian B. WALKER ◽  
Patrick DOYLE ◽  
Gareth WILLIAMS
Keyword(s):  
Protein Synthesis ◽  
Oestrogen Receptor ◽  
Calcium Release ◽  
Cardiovascular Effects ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Resistance Arteries ◽  
Protein Synthesis Inhibitors ◽  
Concentration Dependent Manner ◽  
Significant Difference

17β-Oestradiol (17βE2) has vasorelaxant properties that may contribute to its beneficial cardiovascular effects. The mechanism of vasorelaxation remains controversial, but does not appear to involve interaction of 17βE2 with its nuclear receptor. The present study examined the effects on resistance arteries of 17βE2 and its isomer, 17α-oestradiol (17αE2), which does not bind to the classical oestrogen receptor. In arteries precontracted with either noradrenaline or KCl, 17βE2 and 17αE2 caused comparable relaxation in a concentration-dependent manner over the concentration range 0.1–10 μmol/l, with no significant difference in the maximal effect obtained. Pre-incubation of the arteries with 17βE2 or 17αE2 for 15 min reduced the magnitude and duration of the force generated with both noradrenaline and KCl to a comparable degree. Vasorelaxation induced by either 17βE2 or 17αE2 was not blocked by an inhibitor of NO synthase or by protein synthesis inhibitors, indicating that vasodilatation is not dependent upon either NO generation or protein synthesis. In the absence of extracellular calcium, both oestradiols still relaxed arteries precontracted with NA, suggesting that they inhibit intracellular calcium release. Both 17βE2 and 17αE2 therefore have important and comparable vasorelaxant properties that do not require interaction with the nuclear oestrogen receptor. Direct interactions with the cell membrane or with ion-channel proteins may be responsible.

scholarly journals A Novel Synthetic Dihydroindeno[1,2-b] Indole Derivative (LS-2-3j) Reverses ABCB1- and ABCG2-Mediated Multidrug Resistance in Cancer Cells

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3264 ◽  
Author(s):  
Chao Guo ◽  
Fangyuan Liu ◽  
Jie Qi ◽  
Jiahui Ma ◽  
Shiqi Lin ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Protein Expression ◽  
Atpase Activity ◽  
Cancer Cells ◽  
Abc Transporter ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Expression Levels ◽  
Chemotherapy Drugs ◽  
Diphenyltetrazolium Bromide

10-oxo-5-(3-(pyrrolidin-1-yl) propyl)-5,10-dihydroindeno [1,2-b] indol-9-yl propionate (LS-2-3j) is a new chemically synthesized indole compound and some related analogues are known to be inhibitors (such as alectinib and Ko143) of ATP-binding cassette (ABC) transporters, especially the ABC transporter subfamily B member 1 (ABCB1) and the ABC transporter subfamily G member 2 (ABCG2). This study aimed to evaluate the multidrug resistance (MDR) reversal effects and associated mechanisms of LS-2-3j in drug-resistant cancer cells. The inhibition of cell proliferation in tested agents was evaluated by the 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. Accumulation or efflux of chemotherapy drugs was analyzed by flow cytometry. The ATPase activity was measured using an ATPase activity assay kit. The mRNA transcripts and protein expression levels were detected by real-time PCR and Western blot, respectively. In this connection, LS-2-3j significantly enhanced the activity of chemotherapeutic drugs in MDR cells and could significantly increase the intracellular accumulation of doxorubicin (DOX) and mitoxantrone (MITX) by inhibiting the function of the efflux pumps in ABCB1- or ABCG2-overexpressing cells. Furthermore, reduced ATPase activity, mRNA transcription, and protein expression levels of ABCB1 and ABCG2 were observed in a concentration dependent manner in MDR cancer cells.

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