Active Chloride Transport by the Gills of Rainbow Trout (Salmo Gairdneri)

1972 ◽  
Vol 56 (1) ◽  
pp. 263-272
Author(s):  
THEODORE H. KERSTETTER ◽  
LEONARD B. KIRSCHNER
Keyword(s):  
Chloride Transport ◽  
Gill Filament ◽  
Salmo Gairdneri ◽  
Apparent Effect ◽  
Chloride Uptake ◽  
Potassium Influx ◽  
The Mean ◽  
Kinetics Of ◽  
Trout Gill ◽  
Penetrating Cations

1. The kinetics of chloride transport by the irrigated trout gill have been studied. The transport system is saturable, and the half-saturation value is about 0.25mM. 2. Chloride uptake occurs equally well from solutions of non-penetrating cations and from NaCl solutions. The presence of potassium in the irrigating solution, however, significantly inhibits chloride uptake. 3. The trout gill is permeable to potassium, and there appears to be an active component to potassium influx. 4. Chloride transport is stimulated by injections of NaHCO3 and (NH4)HCO3. The carbonic anhydrase inhibitor, acetazolamide, has no apparent effect on chloride influx, and it is suggested that if a Cl-/HCO3- exchange exists in the trout gill, sufficient HCO3- can be supplied by the blood. 5. The mean intracellular potential (relative to the irrigating solution) of five gill filament cells was -32 mV. This indicates the presence of an energy barrier to chloride uptake at the outer membrane of the epithelium, and therefore it is postulated that an active step for chloride transport is located on this membrane.

Effects of Perfusate HCO3− and Pco2 on Chloride Uptake in Perfused Gills of Rainbow Trout (Salmo gairdneri)

1984 ◽  
Vol 41 (12) ◽  
pp. 1768-1773 ◽  
Author(s):  
S. F. Perry ◽  
P. Payan ◽  
J. P. Girard
Keyword(s):  
Rainbow Trout ◽  
Carbonic Anhydrase ◽  
Chloride Transport ◽  
Salmo Gairdneri ◽  
Gill Epithelium ◽  
Major Pathway ◽  
Chloride Uptake ◽  
Transport Inhibitors ◽  
Initial Results ◽  
Stimulation Of

Experiments were conducted using a saline-perfused trout (Salmo gairdneri) head preparation in an attempt to determine the origin of HCO3− involved in gill apical Cl−/HCO3− exchange, the possibilities being plasma CO2 or HCO3−. Initial results showed that branchial Cl− influx was stimulated both by increased perfusate [HCO3−] and Pco2. Subsequent experiments employing the chloride transport inhibitors, SITS and thiocyanate, indicated that stimulation of Cl− influx by HCO3− probably was due to gill hemodynamic alterations and not to increased entry of HCO3− into the gill epithelium. We conclude that CO2 entry into the gill epithelium from plasma and its subsequent hydration to HCO3− and H+, by carbonic anhydrase, is a major pathway by which HCQ3− for Cl−/HCO3− exchange is generated.

Osmoregulation in the terrestrial Christmas Island red crab Gecarcoidea natalis (Brachyura: Gecarcinidae): modulation of branchial chloride uptake from the urine

2002 ◽  
Vol 205 (20) ◽  
pp. 3251-3260 ◽  
Author(s):  
H. H. Taylor ◽  
P. Greenaway
Keyword(s):  
Chloride Transport ◽  
High Rate ◽  
Inhibitory Effects ◽  
Chloride Uptake ◽  
Christmas Island ◽  
Urine Composition ◽  
The Mean ◽  
Regulatory Effects ◽  
Gecarcoidea Natalis ◽  
Urine Processing

SUMMARY Crabs generally produce urine iso-osmotic to their haemolymph, but terrestrial crabs are able to vary the composition of their final excretory fluid (termed P) postrenally, in the branchial chambers. Regulatory aspects of branchial urine processing were investigated in the Christmas Island red crab Gecarcoidea natalis acclimated to drinking either freshwater (FW crabs) or 70% seawater (SW crabs). FW crabs released dilute P (mean[Cl-] 8.8 mmol l-1). Drinking 70% seawater caused the mean [Cl-] of the P to rise to 376 mmol l-1 over 5 days,approaching the haemolymph [Cl-]. FW crabs with saline-perfused branchial chambers absorbed chloride at a high rate (10 mmol kg-1h-1), and haemolymph [Cl-] increased at approximately 20 mmol l-1 h-1. SW crabs exhibited elevated haemolymph osmolalities and ion concentrations and zero branchial chloride uptake. FW crabs that were salt-loaded by branchial chamber perfusion over several hours downregulated, and eventually ceased, chloride uptake. The rate of downregulation, but not the initial chloride flux, was dependent on initial haemolymph [Cl-]. Intravascular infusion of NaCl caused immediate reduction in branchial [Cl-] of 80%. Crabs ingested and regurgitated the perfusion saline, supporting suggestions that reingestion of urine could conserve water and ions. Dopamine upregulated branchial chloride transport in G. natalis. This is consistent with the ion-regulatory effects of dopamine in euryhaline marine brachyurans but contrasts with its inhibitory effects in the terrestrial anomuran Birgus latro. Dopamine increased the rate of urine release in FW crabs. Urine composition appears to be unimportant in ionic regulation, except in the case of magnesium, levels of which were elevated in the urine of SW crabs.

Kinetics of silicon nitride crystallization in N+-implanted silicon

1989 ◽  
Vol 4 (2) ◽  
pp. 394-398 ◽  
Author(s):  
V. S. Kaushik ◽  
A. K. Datye ◽  
D. L. Kendall ◽  
B. Martinez-Tovar ◽  
D. S. Simons ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Wafer Surface ◽  
Amorphous Silicon Nitride ◽  
Silicon Lattice ◽  
Nitrogen Ions ◽  
The Mean ◽  
Nitride Layers ◽  
Kinetics Of

Implantation of nitrogen at 150 KeV and a dose of 1 ⊠ 1018/cm2 into (110) silicon results in the formation of an amorphized layer at the mean ion range, and a deeper tail of nitrogen ions. Annealing studies show that the amorphized layer recrystallizes into a continuous polycrystalline Si3N4 layer after annealing for 1 h at 1200 °C. In contrast, the deeper nitrogen fraction forms discrete precipitates (located 1μm below the wafer surface) in less than 1 min at this temperature. The arcal density of these precipitates is 5 ⊠ 107/cm2 compared with a nuclei density of 1.6 ⊠ 105/cm2 in the amorphized layer at comparable annealing times. These data suggest that the nucleation step limits the recrystallization rate of amorphous silicon nitride to form continuous buried nitride layers. The nitrogen located within the damaged crystalline silicon lattice precipitates very rapidly, yielding semicoherent crystallites of β–Si3N4.

scholarly journals Kinetics of drying of basil leaves (Ocimum basilicum L.) in the infrared

2012 ◽  
Vol 16 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Renata C. dos Reis ◽  
Ivano A. Devilla ◽  
Diego P. R. Ascheri ◽  
Ana C. O. Servulo ◽  
Athina B. M. Souza
Keyword(s):  
Experimental Data ◽  
Ocimum Basilicum ◽  
Coefficient Of Determination ◽  
Chisquare Test ◽  
The Mean ◽  
Drying Curves ◽  
The One ◽  
Increasing Temperature ◽  
Air Circulation ◽  
Kinetics Of

The objective of this paper was to model the drying curves of the leaves of basil (Ocimum basilicum L.) in the infrared at temperatures of 50, 60, 70 and 80 ºC and to evaluate the influence of drying temperature on the color of dried leaves. Drying was conducted in infrared dryer with temperature and greenhouse air circulation. Experimental data were fitted to eight mathematical models. The magnitude of the coefficient of determination (R²), the mean relative error (P), the estimated mean error (SE) and chisquare test (χ2) were used to verify the degree of fitness of the models. From the study it was concluded that: a) the behavior of the drying curves of basil leaves was similar to most agricultural products, the drying times in the infrared were less than the drying times in an oven with air circulation, b) the mathematical drying model proposed by Midilli et al. (2002) was the one which best adjusted to the experimental data, c) the diffusion coefficient ranged from 9.10 x 10-12 to 2.92 x 10-11 m² s-1 and d) the color of the samples was highly influenced by drying, becoming darker due to loss of chlorophyll with increasing temperature.

Reabsorption kinetics of albumin from pleural space of dogs

1988 ◽  
Vol 255 (2) ◽  
pp. H375-H385 ◽  
Author(s):  
M. Miniati ◽  
J. C. Parker ◽  
M. Pistolesi ◽  
J. T. Cartledge ◽  
D. J. Martin ◽  
...  
Keyword(s):  
Control Mechanism ◽  
Mean Transit Time ◽  
Input Function ◽  
Pleural Space ◽  
Frequency Function ◽  
Liquid Pressure ◽  
Physiological Conditions ◽  
Transit Times ◽  
The Mean ◽  
Kinetics Of

The reabsorption of albumin from the pleural space was measured in eight dogs receiving 0.5 ml intrapleural injection of 131I-labeled albumin and a simultaneous intravenous injection of 125I-labeled albumin. Plasma curves for both tracers were obtained over 24 h. The 125I-albumin curve served as input function of albumin for interstitial spaces, including pleura, whereas the 131I-albumin curve represented the output function from pleural space. The frequency function of albumin transit times from pleural space to plasma was obtained by deconvolution of input-output plasma curves. Plasma recovery of 131I-albumin was complete by 24 h, and the mean transit time from pleura to plasma averaged 7.95 +/- 1.57 (SD) h. Albumin reabsorption occurred mainly via lymphatics as indicated by experiments in 16 additional dogs in which their right lymph ducts or thoracic ducts were ligated before intrapleural injection. A pleural lymph flow of 0.020 +/- 0.003 (SD) ml.kg-1.h-1 was estimated, which is balanced by a comparable filtration of fluid into the pleural space. This suggests that, under physiological conditions, the subpleural lymphatics represent an important control mechanism of pleural liquid pressure.

scholarly journals Temperature Dependent Seed Germination of Dalbergia nigra Allem (Leguminosae)

2001 ◽  
Vol 44 (4) ◽  
pp. 401-404 ◽  
Author(s):  
Fernanda G. A. Ferraz-Grande ◽  
Massanori Takaki
Keyword(s):  
Seed Germination ◽  
Endangered Species ◽  
High Temperatures ◽  
Broad Temperature Range ◽  
Optimum Temperature ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Dalbergia Nigra ◽  
The Mean ◽  
Kinetics Of

The germination of endangered species Dalbergia nigra was studied and 30.5° C was found as optimum temperature, although the species presented a broad temperature range where germination occurs and light had no effect. The analysis of kinetics of seed germination confirmed the asynchronized germination below and above the optimum temperature. The light insensitive seed and germination also at high temperatures indicated that D. nigra could occur both in understories and gaps where the mean temperature was high.

scholarly journals Modelling Activity and Durability of Electrocatalysts from a Statistical Perspective

2021 ◽  
Author(s):  
Jun Huang
Keyword(s):  
Exponential Decay ◽  
Analytical Solutions ◽  
Electrocatalytic Activity ◽  
Active Sites ◽  
Simple Theory ◽  
Exact Analytical Solutions ◽  
Modelling Activity ◽  
Closing The Gap ◽  
The Mean ◽  
Kinetics Of

<p>We develop a theory to investigate how energetic nonhomogeneity of active sites determines the overall activity of an electrocatalyst and how the evolution of the nonhomogeneity determines the overall durability. The simple theory is amenable to exact analytical solutions and thus fosters an in-depth transparent analysis. It is revealed that nonhomogeneity does not necessarily diminish the electrocatalytic activity; instead, the highest overall activity is obtained with a suitable level of nonhomogeneity that is commensurate with the mean property. The evolution kinetics of nonhomogeneity is described by using the Fokker-Planck theory. Exponential decay of the activity is predicted theoretically and confirmed experimentally. The present work represents a first step toward closing the gap between model and practical electrocatalysts using statistical considerations.</p>

Oral administration of radioactive sulfate to measure extracellular fluid space in man

1976 ◽  
Vol 40 (4) ◽  
pp. 648-650 ◽  
Author(s):  
J. H. Bauer
Keyword(s):  
Oral Administration ◽  
Human Subjects ◽  
Extracellular Fluid ◽  
Mean Difference ◽  
Routes Of Administration ◽  
Extracellular Fluid Space ◽  
The Mean ◽  
Kinetics Of ◽  
Plasma Activity

Radioactive sulfate-35 (35S) was administered to eight human subjects intravenously and orally, to compare respective kinetics of distribution. Intravenously administered 35S attained equilibration within 60–90 min. Orally administered 35S attained equilibration within 60–105 min and thereafter achieved plasma activity equivalent to the intravenously administered tracer. Eighty percent or greater of the 35S dose was recovered in the 24-h urine, following either intravenous or oral administration. The mean extracellular fluid space demonstrated less than 9% mean difference between routes of administration. It is concluded that 35S is completely absorbed at tracer doses, and may be administered orally as a reliable substitute for intravenously administered 35S for measuring extracellular fluid space.

scholarly journals Kinetics of Systemic Invasion and Latent and Incubation Periods of Tomato severe rugose virus and Tomato chlorosis virus in Single and Co-Infections in Tomato Plants

2019 ◽  
Vol 109 (3) ◽  
pp. 480-487 ◽  
Author(s):  
Gabriel Madoglio Favara ◽  
Daiana Bampi ◽  
Juan Pablo Edwards Molina ◽  
Jorge Alberto Marques Rezende
Keyword(s):  
Middle East ◽  
East Asia ◽  
Latent Period ◽  
Asia Minor ◽  
Tomato Plants ◽  
Incubation Periods ◽  
Infected Tomato ◽  
The Mean ◽  
Tomato Chlorosis Virus ◽  
Kinetics Of

Tomato severe rugose virus (ToSRV) and Tomato chlorosis virus (ToCV) are among the major viruses that affect tomato (Solanum lycopersicum) development and yield in Brazil. ToSRV and ToCV are transmitted in a persistent circulative and semipersistent manner, respectively, by the whitefly Bemisia tabaci Middle East-Asia Minor 1, considered the main vector of these viruses. In this study, the kinetics of systemic invasion and the latent and incubation periods of ToSRV and ToCV were evaluated in singly and doubly infected tomato plants. Both viruses moved systemically into tomato plants as early as 1 day after inoculation. The mean ToCV latent periods in single infections and co-infections with ToSRV were 13 and 11 days, respectively, while incubation periods in single and co-infections were, on average, 30 and 31 days, respectively. For ToSRV, the mean latent period was 7 days in single infections and 6 days in co-infections with ToCV. Incubation periods were, on average, 18 and 17 days in single and co-infections, respectively. Because latent periods for both viruses were shorter than their respective incubation periods, field-infected tomato plants may act as sources of inocula soon after infection and before onset of symptoms.

Effects of luteectomy on the maintenance of pregnancy, circulating progesterone concentrations and lambing performance in sheep

1999 ◽  
Vol 11 (6) ◽  
pp. 317 ◽  
Author(s):  
K. H. Al-Gubory ◽  
A. Solari ◽  
B. Mirman
Keyword(s):  
Corpus Luteum ◽  
Maternal Plasma ◽  
Gestation Length ◽  
Apparent Effect ◽  
Plasma Progesterone ◽  
Time Period ◽  
Before And After ◽  
The Mean

In sheep, there have been few and conflicting data regarding the necessity of the corpus luteum (CL) for the maintenance of pregnancy. The aims of the present study were to examine the effect of luteectomy on and after Day 50 of pregnancy on maternal plasma progesterone concentrations and the progression of pregnancy, to determine the minimum placental progesterone support required for the maintenance of pregnancy, and to evaluate the effect of luteectomy on lambing performance. In Experiment 1, four ewes luteectomized on Day 50 of pregnancy aborted 2–7 days after surgery, whereas pregnancy progressed and parturition occurred between Days 143 and 149, with live lambs, in three of four ewes and in four ewes luteectomized on Days 60 and 70 of pregnancy respectively. The mean ( SEM) progesterone concentrations on the day before and one day after luteectomy decreased from 4.87 0.85 to 0.42 0.06 ng mL –1 (P<0.01), from 4.57 0.51 to 0.80 0.12 ng mL –1 (P<0.02) and from 6.05 0.52 to 1.67 0.11 ng mL –1 (P<0.01), respectively, for the ewes luteectomized on Days 50, 60 and 70 of pregnancy. The fall in progesterone concentrations was 90%, 80% and 71%, respectively, for the ewes luteectomized on Days 50, 60 and 70 of pregnancy. In Experiment 2, pregnancy progressed in four ewes luteectomized on Day 70 and parturition occurred between Days 146 and 149, with live lambs. The mean progesterone concentrations declined (P<0.01) from 6.9 0.7 ng mL –1 on the day before luteectomy to 2.1 0.3 ng mL –1 the day after surgery. The concentrations of progesterone in blood collected every 3 h during a 24-h period were stable on Days 60 and 80 of pregnancy, but they were lower (P<0.03) on Day 80 than on Day 60 of pregnancy, for each time period examined. In Experiment 3, the gestation length and birthweights of single, twin and triplet lambs were not different between the control intact ewes (n = 111) and the ewes luteectomized on Days 70–80 of pregnancy (n = 71). Lamb mortality was not different between the two groups (7.2% v. 8.4%, control v. luteectomized). In conclusion, these results showed that (1) the sheep CL is necessary to maintain pregnancy until at least Day 60, (2) progesterone withdrawal induced by luteectomy on and after Day 50 of pregnancy must be of a critical magnitude to provoke abortion, (3) after Day 60 of pregnancy, the CL and the placenta together secrete more progesterone than required for pregnancy maintenance, (4) there is no apparent 24- hour rhythm in maternal plasma progesterone concentrations before and after luteectomy, and (5) luteectomy at mid pregnancy has no apparent effect on gestation length, lamb birthweight or lamb mortality.

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