Prolactin, Cortisol, and Insulin Regulation of Nucleoside Uptake Into Mouse Mammary Gland Explants

2003 ◽  
Vol 228 (7) ◽  
pp. 795-799 ◽  
Author(s):  
James A. Rillema ◽  
Tammy L. Houston ◽  
Kila John-Pierre-Louis
Keyword(s):  
Plasma Concentrations ◽  
Kinetic Studies ◽  
Cell Water ◽  
Uridine Uptake ◽  
L Cell ◽  
Essential Components ◽  
Sodium Dependent ◽  
Pregnant Mice ◽  
Nucleoside Uptake ◽  
Mammary Tissues

Nucleosides are essential components of milk that are used for the nourishment of newborns. Effects of the three primary lactogenic hormones, including prolactin (PRL), insulin (I), and cortisol (H), on nucleoside uptake and incorporation into cultured mammary tissues taken from 12- to 14-day pregnant mice were determined; most experiments focused on the regulation of uridine uptake. Insulin alone, as well as PRL in the presence of insulin and cortisol, was shown to stimulate uridine uptake and incorporation into RNA in mammary explants taken from 12- to 14-day pregnant mice. The PRL effects were expressed at concentrations of 25 ng/ml and above, which are physiological plasma concentrations. In the absence of sodium, uridine uptake and incorporation were diminished, suggesting the presence of a sodium-dependent uridine transporter. In kinetic studies the apparent Km for uridine uptake was calculated to be 312 μM, and the Vmax 2.90 μmol/hr/L cell water; PRL had no effect on the Km but increased the Vmax to 5.88 μmol/hr/L cell water. When assessing uridine uptake in the presence of the other nucleosides at 0.1 mM, only cytidine competed with uridine uptake. The fact that distribution ratios of greater than 15:1 were achieved with uridine indicates that uridine uptake may be via an active transporter. These studies show that PRL enhances uridine update in mammary tissues by stimulating the activity, and probably synthesis, of a sodium-dependent, active uridine and cytosine transporter.

scholarly journals Intracellular and Plasma Trough Concentration and Pharmacogenetics of Telaprevir

2015 ◽  
Vol 18 (2) ◽  
pp. 171 ◽  
Author(s):  
Jessica Cusato ◽  
Sarah Allegra ◽  
Amedeo De Nicolò ◽  
Lucio Boglione ◽  
Giovanna Fatiguso ◽  
...  
Keyword(s):  
Triple Therapy ◽  
Mononuclear Cells ◽  
Linear Regression Analysis ◽  
Plasma Concentrations ◽  
Kinetic Studies ◽  
Pharmacokinetic Data ◽  
Nucleotide Polymorphisms ◽  
Allelic Discrimination ◽  
Peripheral Blood Mononuclear ◽  
Drug Kinetic

PURPOSE: Triple therapy for HCV-1 infection consists in boceprevir or telaprevir, ribavirin and PEG-interferon. Telaprevir is a P-glycoprotein substrate and it is metabolized by CYP3A4/5. No data have been published on intracellular penetration of telaprevir. We determined peripheral blood mononuclear cells (PBMCs) and trough plasma S and R telaprevir isomers concentrations; moreover, we evaluated the influence of some single nucleotide polymorphisms (SNPs) on these pharmacokinetic data after 1 month of triple therapy in humans. METHODS: Plasma and intracellular telaprevir concentrations were determined at the end of dosing interval (Ctrough) using ULPC-MS/MS validated methods; allelic discrimination was performed through real-time PCR. RESULTS: Median telaprevir Ctrough plasma concentrations were 2579 ng/mL and 2233 ng/mL for the pharmacologically more active S, and R, enantiomers, respectively, with median S/R plasma ratio of 1.11. In PBMC, the medians were 6863 ng/mL and 1096 ng/mL for S and R, respectively, with median S/R being 5.73. The PBMC:plasma ratio for S was 2.59 for R. Plasma ribavirin concentrations were directly correlated with plasma S-telaprevir concentrations. In linear regression analysis, only CYP24A1_rs2585428 SNP (p=0.003) and body mass index (p=0.038) were able to predict S-telaprevir PBMC concentrations. CONCLUSIONS: Our preliminary data could increase the understanding of mechanisms underlying telaprevir intracellular and plasma exposure, suggesting the implementation of pharmacogenetics in these drug kinetic studies. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

THE INCORPORATION OF TRITIATED URIDINE IN THE UTERUS AND VAGINA OF THE MOUSE DURING EARLY PREGNANCY

1968 ◽  
Vol 41 (2) ◽  
pp. 189-195 ◽  
Author(s):  
B. G. MILLER ◽  
W. H. OWEN ◽  
C. W. EMMENS
Keyword(s):  
Early Pregnancy ◽  
Ovarian Stimulation ◽  
Pregnant Mouse ◽  
Uridine Uptake ◽  
Pregnant Mice ◽  
Stimulation Of

SUMMARY In the uterus of pregnant mice an increase in uptake of tritiated uridine occurs between days 2 and 3 of pregnancy, followed by a further increase from day 4 onwards. Uridine uptake changes in the same manner in pseudopregnant mice up to day 4, but thereafter declines to a minimum at day 6. The non-pregnant horn of the unilaterally pregnant mouse shows the same changes as the uterus of the pseudopregnant mouse. The results suggest that implantation occurs during a period of declining ovarian stimulation of the uterus and that the increased uptake of uridine in pregnant mice is stimulated locally by implantation.

31P nuclear magnetic resonance and zero-point titration compared for measuring free magnesium concentration in erythrocytes

1991 ◽  
Vol 37 (12) ◽  
pp. 2076-2080 ◽  
Author(s):  
W B Geven ◽  
G M Vogels-Mentink ◽  
J L Willems ◽  
C H v Os ◽  
C W Hilbers ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
31P Nmr ◽  
Zero Point ◽  
Magnesium Concentration ◽  
Cell Water ◽  
Ionized Magnesium ◽  
31P Nuclear Magnetic Resonance ◽  
L Cell ◽  
Magnesium Loss

Abstract Intracellular ionized magnesium concentrations ([Mg2+]i) were measured in erythrocytes by 31P nuclear magnetic resonance (NMR) and zero-point titration in 14 controls and seven patients with renal magnesium loss. The mean intracellular ionized magnesium concentration in controls measured by 31P NMR was 0.20 (SD 0.03) mmol/L cell water, compared with 0.55 (SD 0.12) mmol/L cell water by zero-point titration. Total erythrocyte magnesium content measured with the lysate method was 0.63 mmol/L cell water higher than estimated by 31P NMR, probably because not all magnesium complexes are fully visible to the NMR technique. We found a positive correlation between plasma ultrafiltrable magnesium and [Mg2+]i irrespective of the [Mg2+]i assay used. [Mg2+]i measured with 31P NMR correlated modestly but significantly with [Mg2+]i determined by zero-point titration (r = 0.58, P less than 0.02). Washing erythrocytes before the zero-point titration decreased the ATP content and the cell water fraction, which led to overestimation of [Mg2+]i by zero-point titration. Although absolute values for [Mg2+]i differ with the assay used, both methods determined significantly lower values for [Mg2+]i in patients with isolated renal magnesium loss.

GLUT-1 mediation of rapid glucose transport in dolphin (Tursiops truncatus) red blood cells

1998 ◽  
Vol 274 (1) ◽  
pp. R112-R119 ◽  
Author(s):  
James D. Craik ◽  
James D. Young ◽  
Christoper I. Cheeseman
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Tursiops Truncatus ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Sodium Dodecyl ◽  
Maximal Velocity ◽  
Cell Water ◽  
Glut 1 ◽  
L Cell

d-Glucose entry into erythrocytes from adult dolphins ( Tursiops truncatus) was rapid, showed saturation at high substrate concentrations, and demonstrated a marked stimulation by intracellular d-glucose. Kinetic parameters were estimated from the concentration dependence of initial rates of tracer entry at 6°C: for zero- trans entry, Michaelis constant ( K m) was 0.78 ± 0.10 mM and maximal velocity ( V max) was 300 ± 9 μmol ⋅ l cell water−1 ⋅ min−1; for equilibrium exchange entry, K m was 17.5 ± 0.6 mM and V maxwas 8,675 ± 96 μmol ⋅ l cell water−1 ⋅ min−1. Glucose entry was inhibited by cytochalasin B, and mass law analysis of reversible,d-glucose-displaceable, cytochalasin B binding gave values of 0.37 ± 0.03 nmol/mg membrane protein for maximal binding and 0.48 ± 0.10 μM for the dissociation constant. Dolphin glucose transporter polypeptides were identified on sodium-dodecyl sulfate-polyacrylamide gel electrophoresis immunoblots [using antibodies that recognized human glucose transporter isoform (GLUT-1)] as two molecular species, apparent relative molecular weights of 53,000 and 47,000. Identity of these polypeptides was confirmed byd-glucose-sensitive photolabeling of membranes with [3H]cytochalasin B. Digestion of both dolphin and human red blood cell membranes with glycopeptidase F led to the generation of a sharp band of relative molecular weight 46,000 derived from GLUT-1. Trypsin treatment of human and dolphin erythrocyte membranes generated fragmentation patterns consistent with similar polypeptide structures for GLUT-1 in human and dolphin red blood cells.

Lipoprotein transport in the metabolic syndrome: methodological aspects of stable isotope kinetic studies

2004 ◽  
Vol 107 (3) ◽  
pp. 221-232 ◽  
Author(s):  
Dick C. CHAN ◽  
P. Hugh R. BARRETT ◽  
Gerald F. WATTS
Keyword(s):  
Metabolic Syndrome ◽  
Stable Isotope ◽  
Plasma Concentrations ◽  
Lipoprotein Metabolism ◽  
Visceral Obesity ◽  
Kinetic Studies ◽  
Kinetic Properties ◽  
The Metabolic Syndrome ◽  
Methodological Aspects

The metabolic syndrome encapsulates visceral obesity, insulin resistance, diabetes, hypertension and dyslipidaemia. Dyslipidaemia is a cardinal feature of the metabolic syndrome that accelerates the risk of cardiovascular disease. It is usually characterized by high plasma concentrations of triacylglycerol (triglyceride)-rich and apoB (apolipoprotein B)-containing lipoproteins, with depressed concentrations of HDL (high-density lipoprotein). However, lipoprotein metabolism is complex and abnormal plasma concentrations can result from alterations in the rates of production and/or catabolism of these lipoprotein particles. Our in vivo understanding of kinetic defects in lipoprotein metabolism in the metabolic syndrome has been achieved chiefly by ongoing developments in the use of stable isotope tracers and mathematical modelling. This review deals with the methodological aspects of stable isotope kinetic studies. The design of in vivo turnover studies requires considerations related to stable isotope tracer administration, duration of sampling protocol and interpretation of tracer data, all of which are critically dependent on the kinetic properties of the lipoproteins under investigation. Such models provide novel insight that further understanding of metabolic disorders and effects of treatments. Future investigations of the pathophysiology and therapy of the dyslipoproteinaemia of the metabolic syndrome will require the development of novel kinetic methodologies. Specifically, new stable isotope techniques are required for investigating in vivo the turnover of the HDL subpopulation of particles, as well as the cellular efflux of cholesterol into the extracellular space and its subsequent transport in plasma and metabolic fate in the liver.

5-Bromo-2′-Deoxyuridine Stimulates the Pituitary–Adrenal Axis in the Rat: An Effect Blocked Partially by Endothelin-Receptor Antagonists

1996 ◽  
Vol 24 (4) ◽  
pp. 363-368 ◽  
Author(s):  
L K Malendowicz ◽  
G G Nussdorfer
Keyword(s):  
Plasma Concentrations ◽  
Intraperitoneal Administration ◽  
Kinetic Studies ◽  
In Vivo Studies ◽  
Receptor Subtypes ◽  
Main Mode ◽  
Marked Rise ◽  
Adrenal Axis ◽  
Pituitary Adrenal Axis

The bolus intraperitoneal administration of 5-bromo-2′-deoxyuridine (BrdU), at a dose in the range of those currently used for in vivo cell-kinetic studies, was found to provoke a marked rise in the plasma concentrations of adrenocorticotrophic hormone (ACTH), corticosterone and aldosterone in rats. This secretagogue effect of BrdU was annulled by the chronic pretreatment of animals with dexamethasone. The prolonged administration of endothelin-1 (ET-1) raised the blood level of aldosterone (but not of ACTH or corticosterone), and did not alter the response to BrdU. The pretreatment of rats with BQ-123 or BQ-788, two specific antagonists of ET-1 receptor subtypes A and B, did not affect the plasma concentrations of ACTH, corticosterone and aldosterone, but did partially reverse the effects of BrdU. In view of these findings we concluded that BrdU activates the pituitary–adrenal axis in rats, with its main mode of action being pituitary ACTH release; and the suppressive actions of BQ-123 and BQ-788 are independent of their antagonism on ET-1 receptors, and may be due to their interference with the intra-cellular mechanism(s) mediating the secretagogue action of BrdU. This effect of BrdU may have particular relevance to in vivo studies using BrdU labelling to assess cell kinetics of tissues (e.g. lymphatic tissue) affected profoundly by adrenal steroid hormones.

Phosphate homeostasis

2015 ◽  
Author(s):  
Heini Murer ◽  
Jürg Biber ◽  
Carsten A. Wagner
Keyword(s):  
Metabolic Pathways ◽  
Brush Border Membrane ◽  
Renal Excretion ◽  
Plasma Concentrations ◽  
High Energy ◽  
Cellular Functions ◽  
Phosphate Homeostasis ◽  
Phosphate Ions ◽  
Sodium Dependent ◽  
Total Body

Inorganic phosphate ions (H2PO4−/ HPO42−) (abbreviated as Pi) are involved in formation of bone and generation of high-energy bonds (e.g. ATP), metabolic pathways, and regulation of cellular functions. In addition, Pi is a component of biological membranes and nucleic acids. Only about 1% of total body Pi content is present in extracellular fluids, at a plasma concentration in adults within the range 0.8–1.4 mMol/L (at pH 7.4 mostly as HPO42−), with diurnal variations of approximately 0.2 mM. A small amount of plasma Pi is bound to proteins or forms complexes with calcium. Under normal, balanced conditions, absorption of dietary Pi along the small intestine equals the output of Pi via kidney and faeces. Renal excretion of Pi represents the key determinant for the adjustment of normal Pi plasma concentrations. Renal reabsorption of Pi occurs along the proximal tubules by sodium-dependent Pi cotransporters that are strictly localized at the apical brush border membrane. Parathyroid hormone (PTH) and FGF23 are key regulators amongst a myriad of factors controlling excretion of Pi in urine, mostly by changes of the apical abundance of Na/Pi cotransporters. Hypophosphataemia may result in osteomalacia, rickets, muscle weakness, and haemolysis. Hyperphosphataemia can lead to hyperparathyroidism and severe calcifications in different tissues.

Heterogeneity of sodium-dependent D-glucose transport sites along the proximal tubule: evidence from vesicle studies

1982 ◽  
Vol 242 (4) ◽  
pp. F406-F414 ◽  
Author(s):  
R. J. Turner ◽  
A. Moran
Keyword(s):  
Proximal Tubule ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Kinetic Studies ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Outer Cortex ◽  
Sodium Dependent

The glucose transport properties of brush border membrane vesicles from the outer cortex (early proximal tubule) and outer medulla (late proximal tubule) of rabbit kidney were studied. In the outer cortical preparation the behavior of the sodium-dependent component of D-glucose flux indicated the presence of a low-affinity transport system with Km congruent to 6 mM and Vmax congruent to 10 nmol.min-1.mg protein-1 as measured under zero trans conditions at 40 mM NaCl and 17 degrees C. By contrast, in the outer medullary preparation this component of flux behaved as a high-affinity system with Km congruent to 0.35 mM and Vmax congruent to 4 nmol.min-1.mg protein-1. Differences in transport specificity between the two preparations were also indicated and glucose uptake by the outer cortical vesicles was significantly more sensitive to inhibition by phlorizin. These results suggest the existence of two distinct sodium-dependent D-glucose transport systems in the renal proximal tubule brush border membrane. The kinetic studies presented here were done under zero trans sodium and glucose conditions. The rationale and methodology for carrying out these measurements reliably are discussed in detail.

Hypoxia inhibits L-arginine uptake by pulmonary artery endothelial cells

1995 ◽  
Vol 269 (5) ◽  
pp. L574-L580 ◽  
Author(s):  
E. R. Block ◽  
H. Herrera ◽  
M. Couch
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Artery ◽  
Monolayer Culture ◽  
Kinetic Studies ◽  
No Production ◽  
Michaelis Constant ◽  
Arginine Transport ◽  
Sodium Dependent ◽  
Porcine Pulmonary Artery

Under physiological conditions, L-arginine transport by porcine pulmonary artery endothelial cells (PAEC) is mediated by system y+, a sodium-independent transport system that accounts for 60 +/- 5% of L-arginine transport, and system Bo,+, a sodium-dependent system that accounts for 40 +/- 5% of transport. Because NO production is dependent on intracellular L-arginine content and intracellular L-arginine content depends on transport of extracellular L-arginine, we examined the effect of hypoxia on L-arginine transport and intracellular L-arginine content in PAEC. Exposure of passage 3-7 PAEC in monolayer culture to 0% O2 for 4 h decreased L-arginine transport via system y+ from 120 +/- 10 to 81 +/- 23 (in pmol.mg protein-1.30 s-1) (P < 0.001), whereas 20-h exposures decreased transport from 122 +/- 17 to 84 +/- 18 (P < 0.001) in system y+ and from 104 +/- 19 to 90 +/- 26 (P < 0.05) in system Bo,+. Exposure to 5% O2 for 3-5 wk decreased L-arginine transport via system y+ from 128 +/- 15 to 73 +/- 13 (P < 0.001) and via system Bo,+, from 105 +/- 25 to 65 +/- 13 (P < 0.001). Kinetic studies revealed that hypoxia decreased the maximal transport velocity but not the apparent Michaelis constant for both system y+ and system Bo,+, and the decreases in transport were not reversible after return to normoxia for up to 24 h. Long-term exposure, i.e., 3-5 wk, to 5% O2 also resulted in decreases in intracellular L-arginine content (0.75 +/- 0.10 vs. 0.49 +/- 0.09 nmol/10(6) cells, P < 0.05) which did not reverse after return to normoxia for 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of L-glutamine transport by pulmonary artery endothelial cells

1991 ◽  
Vol 260 (4) ◽  
pp. L241-L246 ◽  
Author(s):  
K. Herskowitz ◽  
B. P. Bode ◽  
E. R. Block ◽  
W. W. Souba
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Artery ◽  
Hormonal Regulation ◽  
Kinetic Studies ◽  
High Affinity ◽  
Sodium Dependent ◽  
Porcine Pulmonary Artery ◽  
External Ph ◽  
Glutamine Uptake

This study characterized the transport of L-glutamine by porcine pulmonary artery endothelial cells (PAECs). Uptake of 50 microM glutamine was determined and found to be linear for at least 45 min. The sodium-dependent velocity represented greater than 95% of the total uptake at all time points. Kinetic studies of glutamine uptake at concentrations between 0.005 and 10 mM showed a single saturable high-affinity carrier with a Michaelis constant of 100 +/- 6 microM and a maximal transport velocity of 1.0 +/- 0.08 nmol.mg protein-1.30s-1. Glutamine uptake by PAECs was markedly inhibited in the presence of L-cysteine, L-threonine, or L-alanine; lesser degrees of inhibition occurred when histidine and arginine were added. 2-Methylaminoisobutyric acid and 2-aminobicyclo [2,2,1]heptanedicarboxylic acid had little effect on glutamine uptake. Lithium did not substitute for sodium, strongly suggesting that L-glutamine was not transported by system N. Furthermore, transport of glutamine was not affected by hormones or by changes in external pH. Based on the intolerance of this high-affinity carrier to N-methylated substrate, its insensitivity to pH and hormonal regulation, and the failure of lithium to substitute for sodium, as well as its inhibition by alanine and cysteine, we conclude that in porcine pulmonary artery endothelial cells L-glutamine is predominantly taken up through system ASC.

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