scholarly journals Chloroquine Transport inPlasmodium falciparum. 1. Influx and Efflux Kinetics for Live Trophozoite Parasites Using a Novel Fluorescent Chloroquine Probe

Biochemistry ◽  
2009 ◽  
Vol 48 (40) ◽  
pp. 9471-9481 ◽  
Author(s):  
Mynthia Cabrera ◽  
Jayakumar Natarajan ◽  
Michelle F. Paguio ◽  
Christian Wolf ◽  
Jeffrey S. Urbach ◽  
...  
Keyword(s):  
Efflux Kinetics

Kinetics of endosomal pH evolution in Dictyostelium discoideum amoebae. Study by fluorescence spectroscopy

1993 ◽  
Vol 105 (3) ◽  
pp. 861-866 ◽  
Author(s):  
L. Aubry ◽  
G. Klein ◽  
J.L. Martiel ◽  
M. Satre
Keyword(s):  
Dictyostelium Discoideum ◽  
Fluid Phase ◽  
Lag Phase ◽  
Nutritive Medium ◽  
Chase Period ◽  
Endosomal Acidification ◽  
Fluid Phase Endocytosis ◽  
Endosomal Ph ◽  
Efflux Kinetics ◽  
Secondary Lysosomes

The evolution of endo-lysosomal pH in Dictyostelium discoideum amoebae was examined during fluid-phase endocytosis. Pulse-chase experiments were conducted in nutritive medium or in non-nutritive medium using fluorescein labelled dextran (FITC-dextran) as fluid-phase marker and pH probe. In both conditions, efflux kinetics were characterized by an extended lag phase lasting for 45–60 min and corresponding to intracellular transit of FITC-dextran cohort. During the chase period, endosomal pH decreased during approximately 20 min from extracellular pH down to pH 4.6-5.0, then, it increased within the next 20–40 min to reach pH 6.0-6.2. It was only at this stage that FITC-dextran was released back into the medium with pseudo first-order kinetics. A vacuolar H(+)-ATPase is involved in endosomal acidification as the acidification process was markedly reduced in mutant strain HGR8, partially defective in vacuolar H(+)-ATPase and in parent type strain AX2 by bafilomycin A1, a selective inhibitor of this enzyme. Our data suggest that endocytic cargo is channeled from endosomes to secondary lysosomes that are actively linked to the plasma membrane via recycling vesicles.

Sodium tracer kinetics and transmembrane flux in tissue-cultured chick heart cells

1982 ◽  
Vol 243 (3) ◽  
pp. C169-C176 ◽  
Author(s):  
D. M. Wheeler ◽  
C. R. Horres ◽  
M. Lieberman
Keyword(s):  
Steady State ◽  
Slow Component ◽  
Heart Cells ◽  
Kinetic Measurements ◽  
Considerable Difficulty ◽  
Control Value ◽  
Na Efflux ◽  
Nonmuscle Cells ◽  
Chick Heart ◽  
Efflux Kinetics

Considerable difficulty has been encountered in defining the physiological significance of sodium tracer kinetic measurements in cardiac muscle. In this study, 24Na+ efflux experiments were performed by directly monitoring tissue radioactivity during the superfusion of growth-oriented embryonic chick heart cells in tissue cultured. The cellular 24Na+ efflux from contractile preparations exhibited at least two exponential components whereas noncontractile, fibroblastlike preparations had a single efflux component similar in rate to the slower component of the contractile preparations. We concluded that the slow component represents efflux from nonmuscle cells, whereas the faster component reflects the muscle cell compartment. The mean Na+ efflux rate constants for contractile preparations (beating 150 min-1) were 3.1 and 0.35 min-1. Intracellular Na+ concentrations, as determined by isotope uptake and by flame photometry, were 18 and 16 mM for contractile and nonmuscle preparations, respectively. The steady-state, transmembrane fluxes are 98 and 5 pmol . cm-2 . s-1 for muscle and nonmuscle cells, respectively. The Na+ efflux kinetics in 10(-4) M ouabain were reduced by approximately 16% from the control value. These findings indicate that the greater part of the steady-state Na+ efflux in cultured heart cells is due to mechanisms other than the Na+-K+ pump.

Trans-stimulation of 13NH4+ efflux provides evidence for the cytosolic origin of tracer in the compartmental analysis of barley roots

2003 ◽  
Vol 30 (12) ◽  
pp. 1233 ◽  
Author(s):  
Dev T. Britto ◽  
Herbert J. Kronzucker
Keyword(s):  
Compartmental Analysis ◽  
Fold Increase ◽  
Model System ◽  
Hordeum Vulgare L ◽  
Root Cells ◽  
Transport Studies ◽  
Efflux Kinetics ◽  
Insight Into ◽  
Pool Sizes ◽  
Stimulation Of

The analysis of tracer efflux kinetics is fundamental to membrane transport studies, but requires the rigorous identification of subcellular tracer sources. We present a solution to this problem through the analysis of sharp increases in 13NH4+ efflux from roots of radiolabelled barley (Hordeum vulgare L.) seedlings, in response to a 100-fold increase in external [NH4+]. By comparing these trans-stimulation data with a mathematical model incorporating changes in subcellular NH4+ fluxes and pool sizes, we show that the cytosol of root cells is the origin of the tracer efflux. Our analysis provides new insight into the rapidly occurring events underlying compensatory flux regulation during transitions from one nutritional steady state to another, and confirms the validity of compartmental analysis by tracer efflux (CATE) in this important model system.

Examining P-gp efflux kinetics guided by the BDDCS – Rational selection of in vitro assay designs and mathematical models

2019 ◽  
Vol 132 ◽  
pp. 132-141 ◽  
Author(s):  
Julia Riede ◽  
Ken-Ichi Umehara ◽  
Patrick Schweigler ◽  
Felix Huth ◽  
Hilmar Schiller ◽  
...  
Keyword(s):  
Mathematical Models ◽  
In Vitro Assay ◽  
Rational Selection ◽  
Vitro Assay ◽  
Efflux Kinetics ◽  
Selection Of

scholarly journals Anion transport heterogeneity detected by flow cytometric measurement of NBD-taurine efflux kinetics

Cytometry ◽  
1984 ◽  
Vol 5 (3) ◽  
pp. 268-274 ◽  
Author(s):  
K. A. Muirhead ◽  
R. C. Steinfeld ◽  
M. C. Severski ◽  
P. A. Knauf
Keyword(s):  
Anion Transport ◽  
Flow Cytometric ◽  
Flow Cytometric Measurement ◽  
Efflux Kinetics ◽  
Taurine Efflux

Temperature dependence of melphalan efflux kinetics in Chinese hamster ovary cells

1991 ◽  
Vol 41 (8) ◽  
pp. 1173-1177 ◽  
Author(s):  
Diana A. Bates ◽  
Jason H.T. Bates
Keyword(s):  
Temperature Dependence ◽  
Chinese Hamster Ovary ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Ovary Cells ◽  
Efflux Kinetics

Comparison of the accumulation and efflux kinetics of technetium-99m sestamibi and technetium-99m tetrofosmin in an MRP-expressing tumour cell line

2000 ◽  
Vol 27 (12) ◽  
pp. 1786-1792 ◽  
Author(s):  
Keita Utsunomiya ◽  
James R. Ballinger ◽  
Micheline Piquette-Miller ◽  
Andrew M. Rauth ◽  
Wendy Tang ◽  
...  
Keyword(s):  
Cell Line ◽  
Tumour Cell ◽  
Tumour Cell Line ◽  
Technetium 99M Sestamibi ◽  
Technetium 99M ◽  
Technetium 99M Tetrofosmin ◽  
Efflux Kinetics ◽  
Kinetics Of

scholarly journals Active Efflux of Ciprofloxacin from J774 Macrophages through an MRP-Like Transporter

2004 ◽  
Vol 48 (7) ◽  
pp. 2673-2682 ◽  
Author(s):  
Jean-Michel Michot ◽  
Françoise Van Bambeke ◽  
Marie-Paule Mingeot-Leclercq ◽  
Paul M. Tulkens
Keyword(s):  
Atp Depletion ◽  
Glycoprotein P ◽  
Active Efflux ◽  
Drug Concentrations ◽  
Monensin A ◽  
Efflux Kinetics ◽  
Uptake Studies ◽  
Kinetics Of ◽  
Multidrug Resistance Related Protein ◽  
Intermediate Effect

ABSTRACT The accumulation and efflux kinetics of ciprofloxacin have been examined by using murine J774 macrophages. Accumulation (at equilibrium) was increased (three- to fourfold) (i) when cells were incubated with high extracellular drug concentrations (typically 200 mg/liter) as opposed to clinically meaningful concentrations (10 mg/liter or lower), (ii) during ATP- depletion and at acid pH, and (iii) during coincubation with probenecid, gemfibrozil and the preferential multidrug resistance-related protein (MRP) inhibitor MK571. All these conditions were also associated with a marked decrease in ciprofloxacin efflux (half-lives increased from <2 min in controls to up to 10 min). Monensin (a proton ionophore), verapamil, and the preferential P-glycoprotein (P-gp) inhibitor GF120918 had no or only minimal effect, while cyclosporin A, which is not specific for P-gp but also acts on MRP, had an intermediate effect. Short-term uptake studies showed that the influence of the modulators on the apparent drug influx was almost immediate (delay of ≤1 min). Cells made resistant to probenecid and showing a marked overexpression of MRP1 (by Western blot analysis and confocal microscopy) accumulated ciprofloxacin to almost the same extent as did control cells, but efflux was inhibited less by probenecid, gemfibrozil, and MK571. We conclude that ciprofloxacin is subject to constitutive efflux in J774 macrophages through the activity of an MRP-related transporter which is probably distinct from MRP1. We also suggest that the cellular accumulation of ciprofloxacin in wild-type cells is constitutively impaired at therapeutically meaningful concentrations.

scholarly journals A compartmental approach to the mechanism of calcification in hermatypic corals

1996 ◽  
Vol 199 (5) ◽  
pp. 1029-1041 ◽  
Author(s):  
É Tanbutté ◽  
D Allemand ◽  
E Mueller ◽  
J Jaubert
Keyword(s):  
Sea Water ◽  
Lag Phase ◽  
Half Time ◽  
Stylophora Pistillata ◽  
Voltage Dependent ◽  
Hermatypic Corals ◽  
Transport Inhibitors ◽  
Efflux Kinetics ◽  
Carry Over ◽  
Ca2 Channels

Ca2+ compartments, Ca2+ transport and the calcification process were studied by using 45Ca as a tracer. The biological model used was clones of Stylophora pistillata developed into microcolonies whose skeleton is entirely covered by tissues, thus avoiding direct radioisotope exchange between the sea water and the skeleton. The study of Ca2+ compartments was performed by measuring two complementary parameters: Ca2+ influx and Ca2+ efflux kinetics. Kinetic analysis of 45Ca uptake revealed three exchangeable and one non-exchangeable Ca2+ compartments in these microcolonies. The first compartment was saturable with a short half-time (4 min), correlated to external Ca2+ concentration and insensitive to metabolic or ion transport inhibitors. This compartment (72.88 nmol Ca2+ mg-1 protein) has been previously attributed to sea water present in the coelenteron. The second Ca2+ compartment (7.12 nmol Ca2+ mg-1 protein) was soluble in NaOH, saturable with a half-time of 20 min and displayed a combination of Michaelis-Menten kinetics and diffusional entry. It was insensitive to a variety of inhibitors but its loading was stimulated by Ca2+ channel inhibitors. On the basis of uptake experiments, the existence of a third compartment with a rapid turnover rate (about 2 min) and a very small size is predicted. It is suggested that this compartment corresponds to the calicoblastic epithelium. Ca2+ flux through this compartment was facilitated by voltage-dependent Ca2+ channels (with L-type characteristics) and Ca2+-ATPase and was coupled to an anion carrier. Transcellular Ca2+ movement was dependent on the cytoskeleton. The rate of Ca2+ flux across this epithelium was about 975 pmol mg-1 protein min-1. The fourth calcium compartment, corresponding to the skeleton, was soluble in HCl and non-exchangeable. After a short lag phase (about 2 min), the rate of Ca2+ deposition was linear over a period of at least 5 h. The calcification rate was 975 pmol mg-1 protein h-1 at an irradiance of 175 &micro;mol photons m-2 s-1. It followed Michaelis-Menten kinetics and saturated at levels (9 mmol l-1) close to the Ca2+ concentration of sea water. Wash-out (efflux) experiments employing several different protocols allowed identification of six compartments. The first two compartments were extracellular (bulk extracolonial water and coelenteron). The third compartment may be part of the second Ca2+ compartment identified by influx experiments. A fourth compartment was sensitive to the Ca2+ channel inhibitor D600 and appeared to be associated with the NaOH-soluble (tissue) Ca2+ pool. Two compartments were identified during skeletal efflux, the first being small and due to either tissue carry-over or a labile skeletal compartment. The second compartment corresponded to bulk skeletal deposition. The various efflux protocols produced varying estimates of tissue Ca2+ levels and calcification rates and, thus, coral post-incubation processing has a profound impact on experimental interpretation.

Analysis of the Efflux Kinetics of Sodium from Small Cylinders of Rabbit Kidney Cortex

1965 ◽  
Vol 65 (1-2) ◽  
pp. 105-119
Author(s):  
E. Bojesen ◽  
P. P. Leyssac ◽  
B. Svejgaard Nielsen
Keyword(s):  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Efflux Kinetics ◽  
Kinetics Of
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