scholarly journals Zinc transport in rabbit tissues. Some hormonal aspects of the turnover of zinc in female reproductive organs, liver and body fluids

1972 ◽  
Vol 126 (4) ◽  
pp. 869-876 ◽  
Author(s):  
J. E. A. McIntosh ◽  
C. Lutwak-Mann
Keyword(s):  
Corpus Luteum ◽  
Specific Radioactivity ◽  
Numerical Procedure ◽  
Zinc Content ◽  
Placental Tissue ◽  
Compartmental Analysis ◽  
Turnover Time ◽  
Zinc Transport ◽  
Uterine Fluid ◽  
Kinetics Of

1. To investigate the influence of hormonal conditions upon the kinetics of zinc transport, specific radioactivity of 65Zn was determined in certain tissues and fluids from unmated or pregnant rabbits during the first half of gestation. 2. Compartmental analysis was used to find the simplest mathematical model that simulated satisfactorily tracer behaviour. Models were fitted to experimental results by a numerical procedure using a computer. 3. The kinetics of zinc exchange in most tissues investigated could adequately be described by a three-compartment model, in which total tissue zinc content was divided into a rapidly exchanging pool, with a turnover time of about 1h, and a slowly exchanging pool, the turnover time of which was in liver 15h, in peak-stage corpus luteum 8h, and in the other tissues 30–70h. 4. In rabbit endometrium zinc transport varied with hormonal conditions, the turnover rate being higher in non-pregnant than pregnant endometrium. 5. Uptake of 65Zn by uterine fluid was slow, and in the free-lying embryos (blastocysts) slower still, in keeping with uterine fluid acting as carrier of zinc into the unimplanted embryos. 6. In placental tissue zinc transport varied with gestational stage. Foetal placenta exchanged zinc with blood plasma four times faster than maternal placenta. In foetuses zinc turnover time and flux equalled that of the slow zinc compartment in foetal placenta. 7. Corpus luteum on days 5–6 of gestation showed peak specific radioactivity and zinc flux values, which exceeded those of all other tissues. 8. In liver the slow zinc compartment had a higher rate of turnover than corresponding compartments in tissues other than peak-stage corpus luteum, but no hormone-dependent changes were observed. 9. Zinc uptake by erythrocytes was the slowest of all examined.

scholarly journals Calcium transport in the early conceptus and associated maternal tissues in the rabbit

1974 ◽  
Vol 138 (1) ◽  
pp. 97-105 ◽  
Author(s):  
J. E. A. McIntosh ◽  
C. Lutwak-Mann
Keyword(s):  
Blood Plasma ◽  
Calcium Transport ◽  
Specific Radioactivity ◽  
Turnover Time ◽  
Calcium Flux ◽  
Experimental Conditions ◽  
Hormone Substitution ◽  
Uterine Fluid

1. The kinetics of calcium transport were studied in unmated (oestrous) and pregnant rabbits in the first half of gestation, with the aim of establishing evidence of hormonal (ovarian) influence on the pattern of transport. 2. The following tissues were examined at short- (45min and 2h) and long-duration (4, 16 and 48h) intervals after parenteral administration of 45Ca or 47Ca: maternal blood plasma, endometrium, uterine fluid, placental tissues, two developmentally disparate stages of rabbit conceptus, namely the unattached blastocyst and the early post-implantation foetus, and bone (femur). 3. Marked variability in calcium content characterized rabbit tissues and body fluids. 4. Compartmental analysis was applied to measurements of specific radioactivity. Oestrous endometrium had the largest rapidly exchanging calcium fraction (turnover time of 12min) and the highest value for calcium flux (500μg of Ca exchanged/h per g fresh wt. of tissue). A marked downward gradient in values of flux existed between the progestational endometrium, uterine fluid and blastocyst; there was a similar gradient between placental tissues and foetus. 5. An hormonal influence on calcium transport was evident in (i) the decrease in specific radioactivity of rabbit blood plasma with advancing pregnancy, (ii) the extraordinarily rapid calcium transport between blood plasma and endometrium, especially in the oestrous stage, and (iii) the effectiveness of ovarian hormone substitution in ovariectomized rabbits. 6. The very low specific radioactivity recorded for bone indicated that only a minute fraction of its calcium was exchanging with that of blood plasma under the experimental conditions examined. 7. The rate of uptake of 45Ca by rabbit blastocysts growing in vitro was one-tenth of that of 22Na, or that recorded for calcium in vivo. 8. Inhibition of carbonic anhydrase activity with acetazolamide in vivo, in maternal erythrocytes, endometrium and placental tissues, produced no appreciable changes in calcium uptake in these tissues or other systems examined as a routine on either day 6 or days 12–14 of gestation.

Energy nutrients modulate the splanchnic sequestration of dietary nitrogen in humans: a compartmental analysis

2001 ◽  
Vol 281 (2) ◽  
pp. E248-E260 ◽  
Author(s):  
H. Fouillet ◽  
C. Gaudichon ◽  
F. Mariotti ◽  
C. Bos ◽  
J. F. Huneau ◽  
...  
Keyword(s):  
Compartmental Model ◽  
Compartmental Analysis ◽  
Dietary Nitrogen ◽  
Amino Acid Availability ◽  
Nutritional Conditions ◽  
Dietary Amino Acid ◽  
Single Meal ◽  
Peripheral Areas ◽  
Kinetics Of ◽  
Insight Into

We used a previously developed compartmental model to assess the postprandial distribution and metabolism of dietary nitrogen (N) in the splanchnic and peripheral areas after the ingestion of a single meal containing milk protein either alone (MP) or with additional sucrose (SMP) or fat (FMP). The addition of fat was predicted to enhance splanchnic dietary N anabolism only transiently, without significantly affecting the global kinetics of splanchnic retention and peripheral uptake. In contrast, the addition of sucrose, which induced hyperinsulinemia, was predicted to enhance dietary N retention and anabolism in the splanchnic bed, thus leading to reduced peripheral dietary amino acid availability and anabolism. The incorporation of dietary N into splanchnic proteins was thus predicted to reach 18, 24, and 35% of ingested N 8 h after MP, FMP, and SMP, respectively. Such a model provides insight into the dynamics of the system in the nonsteady postprandial state and constitutes a useful, explanatory tool to determine the region-specific utilization of dietary N under different nutritional conditions.

K, Cl, and H2O entry in endolymph, perilymph, and cerebrospinal fluid of the rat

1982 ◽  
Vol 243 (2) ◽  
pp. F173-F180 ◽  
Author(s):  
O. Sterkers ◽  
G. Saumon ◽  
P. Tran Ba Huy ◽  
C. Amiel
Keyword(s):  
Cerebrospinal Fluid ◽  
Potassium Chloride ◽  
Intravenous Administration ◽  
Compartmental Analysis ◽  
Water Entry ◽  
Scala Tympani ◽  
Rapid Turnover ◽  
Kinetics Of ◽  
Scala Vestibuli

The kinetics of radioactive potassium, chloride, and water entry into endolymph, perilymph, and cerebrospinal fluid were studied after intravenous administration of tracers in anesthetized and nephrectomized rats. Samples of cochlear endolymph, perilymph of scala vestibuli, perilymph of scala tympani, and cisternal cerebrospinal fluid were obtained. The data showed: 1) a rapid turnover of water in endolymph, perilymph, and cerebrospinal fluid, since 3H2O equilibrated with plasma in a few minutes; 2) a slow entry of 42K and 36Cl in perilymph, since 36Cl equilibrated with plasma after 2 h and 42K did not at 6 h; 3) an extremely slow entry of 42K and 36Cl in endolymph, since no equilibrium with plasma was obtained within the 5 h of the experiments. The comparison of the compartmental analysis of our data with the results of other studies using perilymphatic perfusion of tracers indicated that perilymph rather than plasma may be considered as the precursor of endolymph.

Alteration of adipocyte calcium homeostasis by Escherichia coli endotoxin

1985 ◽  
Vol 248 (3) ◽  
pp. R331-R338
Author(s):  
K. M. Nelson ◽  
J. A. Spitzer
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Calcium Homeostasis ◽  
Compartmental Analysis ◽  
In Vitro Exposure ◽  
Exchange Kinetics ◽  
Intracellular Binding ◽  
Kinetics Of

The present study evaluated calcium homeostasis in rat adipocytes after either in vivo or in vitro exposure to Escherichia coli endotoxin. Fat cells from endotoxin-treated rats showed an enhanced uptake of 45Ca. In an attempt to differentiate between 45Ca binding to the cell surface and intracellular 45Ca accumulation, adipocytes were exposed to 5 mM LaCl3. The amount of 45Ca remaining associated with lanthanum-treated adipocytes was taken to be located intracellularly and was increased in adipocytes from endotoxin-treated rats. The amount of 45Ca displaced by lanthanum was also increased in adipocytes from endotoxin-treated rats. This suggested that the endotoxin-induced increase of 45Ca accumulation included both cell surface and intracellular binding sites. Compartmental analysis of the exchange kinetics of cell-associated 45Ca with 40Ca in the medium indicated a 77% increase in the size of the cell surface compartment of adipocytes from endotoxin-treated rats compared with controls. In addition, endotoxin treatment altered the flux of calcium from the cells to the medium. In vitro exposure of freshly prepared adipocytes to 250 or 750 micrograms endotoxin/ml did not produce a perturbation of adipocyte calcium homeostasis. The results indicate that endotoxin induces alterations in the ability of adipocytes to regulate calcium translocations, suggesting that some metabolic and hormonal aspects of endotoxins' actions may be mediated through perturbation of cellular calcium homeostasis.

scholarly journals Effects of early gestation GH administration on placental and fetal development in sheep

2008 ◽  
Vol 198 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Casey D Wright ◽  
Ryan J Orbus ◽  
Timothy R H Regnault ◽  
Russell V Anthony
Keyword(s):  
Placental Tissue ◽  
Liver Weight ◽  
Luminal Epithelium ◽  
Gh Treatment ◽  
Igf I ◽  
Uterine Fluid ◽  
Igf Binding ◽  
The Impact ◽  
Twin Pregnancies ◽  
Igfbp 3

Ovine GH (oGH) is synthesized in placental tissue during maximal placental growth and development. Our objectives were to localize oGH mRNA in the placenta, and study the impact of exogenous GH on twin pregnancies during the normal window (35–55 days of gestational age; dGA) of placental expression. In situ hybridization localized oGH mRNA in uterine luminal epithelium but not in tissues of fetal origin. While maternal GH and IGF-I concentrations were increased (P<0.001) approximately tenfold, uterine, uterine fluid, placental, and fetal weights were unaffected by treatment at either 55 or 135 dGA. Fetal length, liver weight, and liver weight per kg of body weight were unaffected by maternal GH treatment. However, in the cotyledon, IGF-binding protein (BP)-1 and IGFBP-4 mRNA concentrations were increased (P<0.05), while IGFBP-2 mRNA was decreased (P<0.05). The concentration of mRNA for IGFBP-3 was unaffected by treatment. Within the caruncle, IGFBP-1 mRNA was decreased (P<0.05), while IGFBP-3 and IGFBP-4 mRNA were increased (P<0.05), and IGFBP-2 mRNA was unchanged due to GH treatment. While our data indicate that elevated maternal GH and IGF-I concentrations during early and mid-gestation do not enhance placental and fetal growth in twin pregnancies, localization of GH mRNA in uterine luminal epithelium could explain GHs transitory expression from 35 to 55 dGA, since by the end of this period the majority of the uterine luminal epithelium has fused with chorionic binucleate cells forming the placental syncytium.

Distribution and kinetics of glucose in rats analyzed by noncompartmental and compartmental analysis

1990 ◽  
Vol 259 (2) ◽  
pp. E292-E303 ◽  
Author(s):  
M. Raman ◽  
J. Radziuk ◽  
G. Hetenyi
Keyword(s):  
Steady State ◽  
Rate Constant ◽  
Insulin Infusion ◽  
Compartmental Analysis ◽  
Volume Of Distribution ◽  
Turnover Rates ◽  
Glucose Release ◽  
Steady State Kinetics ◽  
Induced Changes ◽  
Kinetics Of

The steady-state kinetics and distribution of glucose were assessed using noncompartmental and various two-compartment models in rats that were infused with insulin (+/- euglycemic clamping), methylprednisolone (MP), or phlorizin (PHL) as well as rats injected with protamine-zinc-insulin (PZI) or rendered diabetic. Decreases in clearance of glucose (PCR) were greatest with insulin infusion, followed by PHL, MP, and PZI treatments. PCR decreased in diabetes to 25% of normal. With hyperinsulinemia and euglycemia, turnover rates were 1.18 times the rate of glucose infusion. In normal rats the ratio of the contents of the two compartments was 0.6-0.8 (depending on the model). Significant increases, of between 2.8 and 5.2, were observed with insulin infusion and between 0.8 and 1.8 with PHL, again depending on the model. Because PHL-induced changes in PCR are renal, these data suggest that variations in glucose distribution depend on changes in PCR as well as insulin. The intercompartmental rate constant decreased, and the noncompartmental volume of distribution increased to reflect the above changes. In non-steady-state studies, glucose release increased in response to insulin but not to PHL in contrast to other species.

Time course and kinetics of proximal tubular processing of insulin

1992 ◽  
Vol 262 (5) ◽  
pp. F813-F822 ◽  
Author(s):  
S. Nielsen
Keyword(s):  
Steady State ◽  
Time Course ◽  
Accumulation Rate ◽  
Compartmental Analysis ◽  
Proximal Tubules ◽  
Hydrolysis Rate ◽  
Time Courses ◽  
High Concentrations ◽  
Kinetics Of

The present study was undertaken to determine the time courses and kinetics of the subcellular processing of 125I-insulin in isolated and in vitro perfused proximal tubules. Morphometric analysis demonstrated well-preserved ultrastructure after 90 min of perfusion. After luminal perfusion for 90 min the absorption was constant with time and reached steady state within 5 min (177 +/- 7 fg.min-1.mm-1). Also the hydrolysis rate and tubular accumulation rate were constant and averaged 84 +/- 8 and 93 +/- 10 fg.min-1.mm-1, respectively. Free 125I appeared already within 5 min of perfusion and reached steady state within 10 min. From proximal tubules perfused with 125I-insulin for 30 min and chased for 60 min, a compartmental analysis revealed two compartments; half time (t1/2) for delivery of insulin to the lysosomes was determined to be 8.5 min, and t1/2 for lysosomal degradation was 72 min. The results demonstrated that internalization by endocytic invaginations, incorporation in endocytic vacuoles, fusion with lysosomes, and hydrolysis were rapid processes and reached maximum rates within few minutes. A significant transtubular transport of insulin to the peritubular compartment was determined to be a constant rate of 11.2 +/- 0.7 fg.min-1.mm-1. Perfusion of tubules with insulin at high concentrations in the perfusate revealed that the transport was dependent on the absorbed amount and not on the perfused load, compatible with transport through the cells and not via a paracellular mechanism. The intactness of the tight junctions was supported by the following: 1) [14C]inulin leak did not increase with time and 2) enzyme-free intercellular spaces were evident after perfusion for only 5 min with microperoxidase (mol wt of 1,700). The transported 125I-insulin was trichloroacetic acid precipitable and immunoprecipitable.

Passage of bovine serum albumin from the mother to rabbit blastocysts

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 459-469
Author(s):  
Floy L. Crutchfield ◽  
Abraham C. Kulangara
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Double Diffusion ◽  
Early Gestation ◽  
Uterine Lumen ◽  
Intravenous Injections ◽  
Uterine Fluid ◽  
Kinetics Of ◽  
Permeability Rate

Dutch belted rabbits were given single intravenous injections of 100 or 200 mg/kg doses of bovine serum albumin (BSA). BSA in serum and uterine fluid at various times after injection was estimated by a quantitative radial immunodiffusion test, which could measure a minimum of 40 ng. The presence of BSA in uterine fluid was confirmed by immunoelectrophoresis and double diffusion in agar. BSA passes readily into uterine fluid of non-pregnant rabbits, reaching a peak at 12 h after injection, when its concentration is 7–15% of that in serum. About 72 h seems to be required for equilibration of BSA between serum and uterine fluid, at which time the concentration in the former is about 5 times that in the latter. The kinetics of the process is discussed. Compared to the above, passage of BSA into uterine fluid of pregnant rabbits (5–7 days post coitum) is restricted in the following ways. Significant amounts of BSA appear in the fluid only after a maternal dose of 200 mg/kg. BSA in uterine fluid reaches a peak at 24 h after injection, when it is only 4·5% of the serum level. The permeability rate seems to decrease with early gestation. Approximate rates of entry of BSA into uterine lumen of non-pregnant and pregnant rabbits are 0·4 and 0·25 μg/h. BSA seems to be treated like rabbit albumin in its passage across the uterine epithelium. There is no evidence of selection between these proteins.

The concentration of progesterone, 20α-dihydroprogesterone, testosterone, oestrone and oestradiol-17β in serum, amniotic fluid and placental tissue of pregnant rabbits

1982 ◽  
Vol 99 (4) ◽  
pp. 605-611 ◽  
Author(s):  
I. F. Lau ◽  
S. K. Saksena ◽  
R. Salmonsen
Keyword(s):  
Amniotic Fluid ◽  
Blood Serum ◽  
Corpus Luteum ◽  
Peripheral Blood ◽  
Placental Tissue ◽  
Maternal Tissue ◽  
Pregnant Rabbit ◽  
P Content ◽  
The Mean ◽  
Mean Concentration

Abstract. The concentrations of progesterone (Δ4P), 20α-dihydroprogesterone (20α-DHP), testosterone (T), oestrone (E1) and oestradiol-17β (E2β) in peripheral blood serum (PBS), amniotic fluid (AF) and placental tissue of rabbits during gestation were determined by radioimmunoassay. The placenta of the 10-day pregnant rabbit was fragile and composed mainly of maternal tissue. By the 12th day of pregnancy it was separable into maternal and foetal placentae. The mean concentration of Δ4P in PBS rose from 200 pg/ml (day 1 of pregnancy) to 17–21 ng/ml (days 10–15) and decreased gradually to 1 ng/ml a few hours before parturition. The 20α-DHP in PBS also showed an increase from 1.5 ng/ml (day 1) to 12 ng/ml (day 6) but fluctuated thereafter. The concentration of 20α-DHP in the PBS tended to be lower than that of Δ4P during pregnancy until the regression of the corpus luteum. An interesting observation was an increase of T on days 6–8 of pregnancy, the time when implantation occurs. The concentrations of E1 and E2β in PBS remained very low throughout pregnancy. Δ4P and 20α-DHP in AF ranged between 25 pg to 1 ng/ml and in no case during the course of pregnancy were the levels of T, E1 and E2β in AF higher than in PBS. Where the maternal placental Δ4P content remained between 1–2 ng/placenta, the foetal placenta Δ4P rose to a level of 15 ng/placenta by day 31 of pregnancy. A similar trend was recorded for 20α-DHP content. It is concluded that although a parallelism between PBS and myometrial steroid concentration was observed, no relationship could be drawn between the concentrations of steroid in PBS and those of the placental tissue and AF.

scholarly journals Biosynthesis of phosphatidylethanolamines and phosphatidylcholines from ethanolamine and choline in rat liver

1975 ◽  
Vol 146 (2) ◽  
pp. 309-315 ◽  
Author(s):  
R Sundler ◽  
B Akesson
Keyword(s):  
Rat Liver ◽  
Molecular Species ◽  
Kinetic Models ◽  
Quantitative Data ◽  
Specific Radioactivity ◽  
Similar Rate ◽  
Time Intervals ◽  
Previous Suggestion ◽  
Kinetics Of

1. The kinetics of phosphatidylcholine and phosphatidylethanolamine synthesis in rat liver were followed 5-60 min after the intraportal injection of [14-C]choline and [3-H]-ethanolamine. 2. At all time-intervals the specific radioactivity of CDP-choline was only about half that of phosphorylcholine. This indicated that CDP-choline was formed at a similar rate from phosphorylcholine and phosphatidylcholines, the latter probably through the reverse reaction of cholinephosphotransferase (EC 2.7.8.2.). In view of recent data obtained from experiments in vitro this implies a significant role for the cholinephosphotransferase reaction in the turnover of molecular species of phosphatidylcholine. 3. The specific radioactivity of CDP-ethanolamine was about twice that of phosphorylethanolamine at all time-intervals studied. This supports a previous suggestion that the liver phosphorylethanolamine pool is subject to compartmentation and shows that there is no rapid equilibration between different pools. In contrast with a recent study, no evidence was found for any significant methylation of phosphoryl-or CDP-ethanolamine to the corresponding choline derivative. 4. Quantitative data on the biosynthesis of molecular species of phosphoLIPIDS via CDP derivatives were calculated according to simple kinetic models. They were in the same range as those calculated from earlier data on precusors incorporated via diacylglycerols. 5. The proportion of radioactive phosphatidylethanolamines appearing in the plasma was approximately ten times lower than that for phosphatidylcholines. No selectivity was observed in the transfer into plasma of different molecular species of phosphatidylethanolamine.

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