scholarly journals Kinetics of Branchial Calcium Uptake in the Rainbow Trout: Effects of Acclimation to Various External Calcium Levels

1985 ◽  
Vol 116 (1) ◽  
pp. 411-433 ◽  
Author(s):  
S. F. PERRY ◽  
C. M. WOOD
Keyword(s):  
Rainbow Trout ◽  
Calcium Uptake ◽  
Chloride Cells ◽  
Arterial Circulation ◽  
In Vivo Experiments ◽  
Kinetics Of ◽  
Fold Stimulation ◽  
External Calcium

Calcium uptake (JCain) in freshwater rainbow trout (Salmo gairdnen) under control conditions (external [Ca2+] ≃ 1.8 mequivl−1, [NaCl] ≃ 0.8 mequiv 1−1) occurred at approximately equal rates (12–15 μequiv kg−1 h−1) through the gills and the general body surface in vivo. The gut was not involved. Under the same conditions, in vitro branchial JCain in an isolated, saline-perfused head preparation was equal to that in vivo. The cells involved in JinCa are mainly located on lamellae rather than on filaments since 95 % of JinCa occurred across the arterio-arterial circulation of the gill. JinCa, in vitro, displayed Michaelis-Menten kinetics. Acclimation to low external [Ca2+] (50 μequiv 1−1; unchanged [NaCl]) for 1 day caused a five-fold stimulation of JinCa characterized by decreased Km and increased J max. Longer periods of low [Ca2+] acclimation resulted in changes of Jmax only. Jmax gradually returned towards control levels as acclimation time increased, but was still elevated after 30 days. Acclimation to low ambient [Ca2+] caused proliferation and increased exposure of lamellar chloride cells which were correlated with increased Jmax. Fish exposed to high external [Ca2+] (10 mequivl−1; unchanged [NaCl]) displayed reduced JinCa Similar changes in JinCa were observed during in vivo experiments. Plasma Ca2+ concentration remained constant regardless of external [Ca2+], while plasma Na+ and Cl− levels were transiently reduced at 1 day low [Ca2+] exposure but had recovered by 7 days. A possible role for cortisol in Ca2+ regulation is discussed based on observations of cortisol-stimulated lamellar chloride cell proliferation and JinCa, and elevated plasma [cortisol] in low-[Ca2+] acclimated fish.

scholarly journals Mechanisms of zinc uptake in gills of freshwater rainbow trout: interplay with calcium transport

1996 ◽  
Vol 270 (5) ◽  
pp. R1141-R1147 ◽  
Author(s):  
C. Hogstrand ◽  
P. M. Verbost ◽  
S. E. Bonga ◽  
C. M. Wood
Keyword(s):  
Rainbow Trout ◽  
Control Level ◽  
Inhibitory Effect ◽  
Chloride Cells ◽  
Water Addition ◽  
Uptake Mechanism ◽  
Basolateral Membranes ◽  
Control Value

The uptake mechanism of Zn2+ through the gill epithelium of freshwater rainbow trout was investigated both in intact animals and in isolated basolateral membranes. Involvement of the apical Ca2+ uptake sites in Zn2+ uptake was examined in vivo by pharmacological manipulation of the apical Ca2+ permeability. The apical entries of Ca2+ and Zn2+, but not Na2+ and Cl-, were inhibited by addition of La to the water. Addition of 1.0 microM La reduced the influxes of Ca2+ and Zn2+ to 22 +/- 3 and 53 +/- 7% (mean +/- SE) of the control value, respectively. Injection of CaCl2 also reduced the branchial influxes of Ca2+ and Zn2+. This treatment decreased the influx of Ca2- to 45 +/- 4% of the control level and the Zn2+ influx to 68 +/- 5%. These results strongly imply that Zn2+ passes across the apical membrane of the chloride cells of the gills via the same pathway as Ca2+. The presence of an active basolateral transporter for Zn2+ was investigated in vitro on isolated basolateral membranes. There was no ATP-dependent or Na2+(-)gradient driven transport of Zn2+ at physiological Zn2+ activities. The same system was used to study potential effects of Zn2+ on the basolateral Ca2+(-)adenosinetri-phosphatase. Zn2+ was found to be a potent blocker of this transporter, causing a mixed inhibitory effect on the ATP driven Ca2+ transport at a free Zn2+ activity of 100 pM.

Cadmium and calcium uptake in isolated mitochondria-rich cell populations from the gills of the freshwater rainbow trout

2006 ◽  
Vol 291 (1) ◽  
pp. R170-R176 ◽  
Author(s):  
Fernando Galvez ◽  
Denise Wong ◽  
Chris M. Wood
Keyword(s):  
Rainbow Trout ◽  
Cellular Localization ◽  
Calcium Uptake ◽  
High Capacity ◽  
Cell Types ◽  
Isolation Technique ◽  
Pavement Cells ◽  
Gill Cells

A novel cell isolation technique was used to characterize cadmium and calcium uptake in distinct populations of gill cells from the adult rainbow trout ( Oncorhynchus mykiss). A specific population of mitochondria-rich (MR) cell, termed the PNA+ MR cell (PNA is peanut lectin agglutinin), was found to accumulate over threefold more 109Cd than did PNA− MR cells, pavement cells (PV cells), and mucous cells during a 1-h in vivo exposure at 2.4 μg/l 109Cd. In vitro 109Cd exposures, performed in standard PBS and Cl−-free PBS, at concentrations from 1 to 16 μg/l 109Cd, were also carried out to further characterize Cd2+ uptake kinetics. As observed during in vivo experiments, PNA+ MR cells accumulated significantly more 109Cd than did other cell types when exposures were performed by an in vitro procedure in PBS. Under such conditions, Cd2+ accumulation kinetics in all cell types could be described with Michaelis-Menten relationships, with Km values of ∼3.0 μg/l Cd (27 nM) for both MR cell subtypes and 8.6 μg/l Cd (77 nM) for PV cells. In similar experiments performed in Cl−-free conditions, a significant reduction in 109Cd accumulation in PNA+ MR cells was seen but not in PNA− MR or in PV cells. In vitro 45Ca fluxes were also performed to determine the cellular localization of Ca2+ transport in these functionally distinct populations of gill cells. 45Ca uptake was most pronounced in PNA+ MR cells, with levels over threefold higher than those found in either PNA− MR or in PV cells. Results from the present study suggest that the PNA+ MR cell type is a high-affinity and high-capacity site for apical entry of Cd2+ and Ca2+ in the gill epithelium of rainbow trout.

scholarly journals Calcium transport by isolated skin of rainbow trout

1992 ◽  
Vol 166 (1) ◽  
pp. 297-316 ◽  
Author(s):  
W. S. Marshall ◽  
S. E. Bryson ◽  
C. M. Wood
Keyword(s):  
Rainbow Trout ◽  
Cell Density ◽  
Flux Ratio ◽  
Adenosine Monophosphate ◽  
Mucosal Surface ◽  
Chloride Cells ◽  
Serosal Surface ◽  
Ratio Criterion

The skin overlying the cleithrum bone of freshwater-acclimated rainbow trout contains numerous mitochondria-rich (MR) cells, as detected by DASPEI fluorescence. This tissue was mounted in vitro in an Ussing-style chamber with fresh water on the mucosal surface and saline supplemented with bovine serum albumin on the serosal surface. The preparation developed a high transepithelial resistance and a small transepithelial potential (Vt), positive on the serosal side. Radioisotopic flux measurements indicated that the preparation actively transported Ca2+ from the mucosal to the serosal surface, as assessed by the Ussing flux ratio criterion. Ca2+ transport was positively correlated with MR cell density. Cortisol pretreatment in vivo reduced MR cell density and increased Vt but did not significantly alter Ca2+ fluxes. Ca2+ transport was unaffected by adrenergic agonists (10(−5) mol l-1 adrenaline, clonidine, isoprenaline) or cyclic AMP stimulants (10(−3) mol l-1 dibutyryl cyclic adenosine monophosphate, db-cAMP, plus 10(−4) mol l-1 isobutylmethylxanthine, IBMX) applied to the serosal surface. The Ca2+ ionophore ionomycin (1 × 10(−6)-3.2 × 10(−6) mol l-1 on the mucosal surface) increased both unidirectional Ca2+ fluxes and caused Ca2+ to accumulate within the epithelium. Lanthanum (10(−4) mol l-1) did not inhibit unidirectional Ca2+ fluxes, but apparently displaced Ca2+ from binding sites on the mucosal surface. Unlike Ca2+, movements of Na+ and Cl- across the epithelium were passive, as assessed by the flux ratio criterion, and neither adrenaline nor db-cAMP plus IBMX had any effect on Na+ or Cl- fluxes or electrical properties. These results indicate that ion transport across the skin mediated by MR cells (‘chloride cells’) contributes to Ca2+ but not to NaCl balance in freshwater trout.

Erratum

1986 ◽  
Vol 123 (1) ◽  
pp. 216-216
Author(s):  
S. F. PERRY ◽  
C. M. WOOD
Keyword(s):  
Rainbow Trout ◽  
Calcium Uptake ◽  
Kinetics Of ◽  
External Calcium

Kinetics of branchial calcium uptake in the rainbow trout: effects of acclimation to various external calcium levels. J. exp. Biol. 116, 411–433.

scholarly journals Kinetics of Ribosomal Pausing during Programmed −1 Translational Frameshifting

2000 ◽  
Vol 20 (4) ◽  
pp. 1095-1103 ◽  
Author(s):  
John D. Lopinski ◽  
Jonathan D. Dinman ◽  
Jeremy A. Bruenn
Keyword(s):  
Rna Virus ◽  
Peptide Bond ◽  
In Vitro Translation ◽  
Translational Initiation ◽  
Reading Frame ◽  
Translational Frameshifting ◽  
In Vivo Experiments ◽  
Kinetics Of

ABSTRACT In the Saccharomyces cerevisiae double-stranded RNA virus, programmed −1 ribosomal frameshifting is responsible for translation of the second open reading frame of the essential viral RNA. A typical slippery site and downstream pseudoknot are necessary for this frameshifting event, and previous work has demonstrated that ribosomes pause over the slippery site. The translational intermediate associated with a ribosome paused at this position is detected, and, using in vitro translation and quantitative heelprinting, the rates of synthesis, the ribosomal pause time, the proportion of ribosomes paused at the slippery site, and the fraction of paused ribosomes that frameshift are estimated. About 10% of ribosomes pause at the slippery site in vitro, and some 60% of these continue in the −1 frame. Ribosomes that continue in the −1 frame pause about 10 times longer than it takes to complete a peptide bond in vitro. Altering the rate of translational initiation alters the rate of frameshifting in vivo. Our in vitro and in vivo experiments can best be interpreted to mean that there are three methods by which ribosomes pass the frameshift site, only one of which results in frameshifting.

Gut glucose metabolism in rainbow trout: implications in glucose homeostasis and glucosensing capacity

2010 ◽  
Vol 299 (1) ◽  
pp. R19-R32 ◽  
Author(s):  
Sergio Polakof ◽  
Rosa Álvarez ◽  
José L. Soengas
Keyword(s):  
Rainbow Trout ◽  
Amino Acid ◽  
Glucose Metabolism ◽  
Glucose Homeostasis ◽  
Oral Glucose ◽  
Mrna Levels ◽  
Surprising Result ◽  
In Vivo Experiments

The main objective of the present study was to evaluate the relative contribution of the intestine to glucose homeostasis in rainbow trout. In a first set of in vivo experiments trout were subjected to oral glucose treatments alone or in combination with insulin injections to assess changes in glucose-related enzymes activities, metabolite levels, and mRNA levels. Rainbow trout gut displays an important glucose metabolism that includes the ability to store glucose as glycogen (mostly in the muscle layers) and a large capacity to oxidize glucose. This constitutes a surprising result for a carnivorous fish. In a second set of in vivo experiments, trout received an oral amino acid solution alone or in combination with insulin injection to determine whether other factors besides fasting could regulate gluconeogenesis in intestine. The results confirm the absence of regulation of gluconeogenesis in trout gut, which does not respond to hormones, glucose, lactate, or amino acid changes, either in vivo or in vitro. We also fully characterized gut glucose metabolism in vitro. We observed that a large amount of glucose is oxidized to lactate, supporting the importance of glucose in gut metabolism. Moreover, we corroborated the minor actions of insulin in trout gut, whereas other hormones such as glucagon-like peptide-1 and C-peptide appear to be major hormonal regulators of glucose metabolism in fish gut. Finally, we obtained the first evidence for the existence of a glucosensing mechanism in the midgut of this carnivorous species.

scholarly journals In Vivo and In Vitro Effects of Adrenergic Stimulation on Chloride/Bicarbonate Exchange in Rainbow Trout Erythrocytes

1988 ◽  
Vol 140 (1) ◽  
pp. 301-312
Author(s):  
B. L. TUFTS ◽  
R. A. FERGUSON ◽  
R. G. BOUTILIER
Keyword(s):  
Rainbow Trout ◽  
Erythrocyte Membrane ◽  
Ph Gradient ◽  
Exhaustive Exercise ◽  
Adrenergic Stimulation ◽  
In Vivo Experiments ◽  
In Vitro Effects

In vitro and in vivo experiments were carried out to determine the effect of catecholamines on erythrocytic chloride/bicarbonate exchange in the rainbow trout. A further modified boat assay is described and was used to measure bicarbonate flux through intact erythrocytes. Catecholamines had no significant effect on the bicarbonate flux in vitro. The erythrocytes were sensitive to adrenergic stimulation, however, since the agonists used caused a decrease in the pH gradient across the erythrocyte membrane. Exhaustive exercise was associated with an increase in bicarbonate flux through the intact erythrocytes. The mechanism for this increase is not clear, but it is evidently not adrenergic in origin.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Acquired Haemophilia: Functional Study of Antibodies to Factor VIII

1981 ◽  
Vol 45 (03) ◽  
pp. 285-289 ◽  
Author(s):  
J P Allain ◽  
A Gaillandre ◽  
D Frommel
Keyword(s):  
Factor Viii ◽  
Functional Study ◽  
Factor Viii Inhibitor ◽  
Acquired Haemophilia ◽  
Viii Inhibitor ◽  
Kinetics Of ◽  
Antibody Function ◽  
Native Plasma

SummaryFactor VIII complex and its interaction with antibodies to factor VIII have been studied in 17 non-haemophilic patients with factor VIII inhibitor. Low VIII:C and high VIIIR.Ag levels were found in all patients. VIII:WF levels were 50% of those of VTIIRrAg, possibly related to an increase of poorly aggregated and electrophoretically fast moving VIIIR:Ag oligomers.Antibody function has been characterized by kinetics of VIII :C inactivation, saturability by normal plasma and the slope of the affinity curve. Two major patterns were observed:1) Antibodies from 6 patients behaved similarly to those from haemophiliacs by showing second order inhibition kinetics, easy saturability and steep affinity slope (> 1).2) Antibodies from other patients, usually with lower titres, inactivated VIII :C according to complex order kinetics, were not saturable, and had a less steep affinity slope (< 0.7). In native plasma, or after mixing with factor VIII concentrate, antibodies of the second group did not form immune complexes with the whole factor VIII molecular complex. However, dissociation procedures did release some antibodies from apparently low molecular weight complexes formed in vivo or in vitro. For appropriate management of non-haemophilic patients with factor VIII inhibitor, it is important to determine the functional properties of their antibodies to factor VIII.

Sign in / Sign up

Export Citation Format

Share Document