Composition of fluid transported by locust ileum: influence of natural stimulants and luminal ion ratios

1989 ◽  
Vol 67 (11) ◽  
pp. 2662-2668 ◽  
Author(s):  
R. A. Lechleitner ◽  
N. Audsley ◽  
J. E. Phillips
Keyword(s):  
Fluid Transport ◽  
Direct Evidence ◽  
High Capacity ◽  
Fold Increase ◽  
Hormonal Control ◽  
Corpus Cardiacum ◽  
Ventral Ganglion ◽  
Nacl Transport ◽  
Stimulation Of

Unstimulated fluid transport by everted locust ileal sacs in vitro was supported at 50% of control levels by the presence externally of any one of Na+, K+, or Cl−, whereas removal of all but trace levels of these ions reduced fluid transport to 25% of control transport rates. Stimulation of fluid transport by corpus cardiacum or fifth ventral ganglion extracts did not occur unless Cl− was present. The presence of Na+ or K+ was also required for maximum stimulation of fluid transport by these factors, the greatest stimulation occurring when the Na+:K+ ratio was 1:1. Cyclic AMP, and corpus cardiacum and fifth ventral ganglion extracts all stimulated Na+, Cl−, and K+ absorption across everted ileal sacs. Stimulation of fluid transport by these factors largely eliminated the anion deficit (Na+ + K+−Cl−) observed under unstimulated conditions. Stimulation caused large decreases in absorbate [Formula: see text] concentrations and pH concurrent with the increased absorbate Cl− levels. These results indicate a switch from low-capacity NaHCO3 plus NaCl transport under unstimulated conditions to high-capacity NaCl transport under stimulated conditions. Stimulation of fluid transport also causes a 3-fold increase in transepithelial potential (hemocoel negative), indicating stimulation of electrogenic anion (Cl−) movement to the hemocoel. These results provide the first direct evidence for hormonal control of Na+ reabsorption in insect excretory systems.

Antidiuretic action of cyclic AMP, corpus cardiacum, and ventral ganglia on fluid absorption across locust ileum in vitro

1989 ◽  
Vol 67 (11) ◽  
pp. 2655-2661 ◽  
Author(s):  
R. A. Lechleitner ◽  
N. Audsley ◽  
J. E. Phillips
Keyword(s):  
Cyclic Amp ◽  
Fluid Transport ◽  
Physiological Saline ◽  
Dependent Manner ◽  
Fluid Absorption ◽  
Corpus Cardiacum ◽  
Ventral Ganglion ◽  
Osmotic Concentration ◽  
Osmotic Permeability

Locust ileal fluid transport (3.0–3.5 μL/h per ileum) and tissue volume were nearly constant after the 1st hour of incubation in physiological saline. Inhibition of absorption by KCN + iodoacetic acid and by azide indicated metabolic dependence of fluid transport. Fluid absorption occurred against osmotic concentration differences of up to 600 mosmol (luminal osmolarity > hemocoel osmolarity). Fluid absorption was stimulated by cyclic AMP, by both nervous and glandular lobes of the corpus cardiacum, and by the fifth ventral ganglion in a dose-dependent manner. All stimulants caused ilea to absorb against larger osmotic concentration differences. Stimulants in corpus cardiacum and fifth ventral ganglion extracts increased the osmotic permeability of the ileal wall at low osmotic concentration differences, whereas cyclic AMP had a much smaller effect on osmotic permeability. The absorbate remained hyperosmotic to the luminal saline under all conditions, and stimulants increased absorbate osmolarity.

scholarly journals Dengue Virus Induces the Expression and Release of Endocan from Endothelial Cells by an NS1–TLR4-Dependent Mechanism

2021 ◽  
Vol 9 (6) ◽  
pp. 1305
Author(s):  
Carlos Alonso Domínguez-Alemán ◽  
Luis Alberto Sánchez-Vargas ◽  
Karina Guadalupe Hernández-Flores ◽  
Andrea Isabel Torres-Zugaide ◽  
Arturo Reyes-Sandoval ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Mrna Expression ◽  
Cell Lines ◽  
Cell Activation ◽  
Dengue Infection ◽  
Elevated Serum ◽  
Fold Increase ◽  
Endothelial Cell Activation ◽  
Stimulation Of

A common hallmark of dengue infections is the dysfunction of the vascular endothelium induced by different biological mechanisms. In this paper, we studied the role of recombinant NS1 proteins representing the four dengue serotypes, and their role in promoting the expression and release of endocan, which is a highly specific biomarker of endothelial cell activation. We evaluated mRNA expression and the levels of endocan protein in vitro following the stimulation of HUVEC and HMEC-1 cell lines with recombinant NS1 proteins. NS1 proteins increase endocan mRNA expression 48 h post-activation in both endothelial cell lines. Endocan mRNA expression levels were higher in HUVEC and HMEC-1 cells stimulated with NS1 proteins than in non-stimulated cells (p < 0.05). A two-fold to three-fold increase in endocan protein release was observed after the stimulation of HUVECs or HMEC-1 cells with NS1 proteins compared with that in non-stimulated cells (p < 0.05). The blockade of Toll-like receptor 4 (TLR-4) signaling on HMEC-1 cells with an antagonistic antibody prevented NS1-dependent endocan production. Dengue-infected patients showed elevated serum endocan levels (≥30 ng/mL) during early dengue infection. High endocan serum levels were associated with laboratory abnormalities, such as lymphopenia and thrombocytopenia, and are associated with the presence of NS1 in the serum.

Atriopeptin stimulation of rectal gland function in Squalus acanthias

1985 ◽  
Vol 249 (3) ◽  
pp. R348-R354 ◽  
Author(s):  
R. Solomon ◽  
M. Taylor ◽  
D. Dorsey ◽  
P. Silva ◽  
F. H. Epstein
Keyword(s):  
Volume Expansion ◽  
Epithelial Transport ◽  
Extracellular Volume ◽  
Chloride Secretion ◽  
Hormonal Control ◽  
Rectal Gland ◽  
Gland Function ◽  
Stimulation Of

The rectal gland of the shark plays a significant role in the homeostasis of extracellular volume. Regulation of rectal gland function is under hormonal control, but the precise identity of the humoral mediator is unknown. Atriopeptin stimulates rectal gland chloride secretion in vivo. This stimulation of epithelial transport is accompanied by systemic and local hemodynamic effects. Atriopeptin also stimulates chloride secretion by the in vitro perfused rectal gland, an effect that is not accompanied by hemodynamic changes. Extracts of shark heart, but not muscle, brain, kidney, or intestine, contain a heat-stable trypsin-sensitive substance capable of in vitro stimulation of rectal gland chloride secretion. Electron micrographic analysis reveals multiple neurosecretory-like granules in atrial cardiocytes that are only rarely seen in ventricular cardiocytes. By using the in vitro perfused gland as a biologic assay, serum obtained after extracellular volume expansion reveals the presence of a rectal gland stimulatory factor that is not present in serum before expansion. These results are consistent with the hypothesis that atriopeptin is present in shark cardiocytes and is released during volume expansion. The atriopeptin stimulates rectal gland chloride secretion, providing a negative feedback mechanism for the regulation of extracellular volume.

Corpus cardiacum stimulated trehalose efflux from cockroach (Periplaneta americana) fat body: control by calcium

1985 ◽  
Vol 63 (1) ◽  
pp. 63-66 ◽  
Author(s):  
J. E. Steele ◽  
T. Paul
Keyword(s):  
Cyclic Amp ◽  
Periplaneta Americana ◽  
Saline Solution ◽  
Fat Body ◽  
Surrounding Medium ◽  
Physiological Saline ◽  
Corpus Cardiacum ◽  
Physiological Saline Solution ◽  
Stimulation Of

Cockroach fat body incubated in a simple physiological saline solution releases trehalose to the surrounding medium. The output of trehalose occurs in the absence of ambient Ca2+ and decreases slowly with time. In two separate experiments, 0.1 mM CaCl2 added to the saline increased the output of trehalose on average by 70% but higher concentrations of Ca2+ did not further increase the efflux of trehalose. Stimulation of trehalose efflux by corpus cardiacum extract is absolutely dependent on extracellular Ca2+, no increase occurring beyond the basal level in the absence of the ion. The activity of corpus cardiacum extract increases as the concentration of CaCl2 is increased to 0.5 mM. This concentration of Ca2+ in the saline permits the extract to increase trehalose efflux by as much as 60% above the basal level. Corpus cardiacum extract, as well as the hypertrehalocaemic agents cyclic AMP and theophylline, increase significantly the influx of Ca2+ into fat body in vitro. The basal efflux of trehalose from fat body and that stimulated by corpus cardiacum extract is not dependent on extracellular Mg2+.

scholarly journals Transport of Salt and Water in Rabbit and Guinea Pig Gall Bladder

1964 ◽  
Vol 48 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Jared M. Diamond
Keyword(s):  
Gall Bladder ◽  
Guinea Pig ◽  
Fluid Transport ◽  
Water Movement ◽  
Bladder Wall ◽  
Nacl Transport ◽  
Exogenous Glucose ◽  
Gall Bladder Wall ◽  
Reproducible Method

A simple and reproducible method has been developed for following fluid transport by an in vitro preparation of mammalian gall bladder, based upon weighing the organ at 5 minute intervals. Both guinea pig and rabbit gall bladders transport NaCl and water in isotonic proportions from lumen to serosa. In the rabbit bicarbonate stimulates transport, but there is no need for exogenous glucose. The transport rate is not affected by removal of potassium from the bathing solutions. Albumin causes a transient weight loss from the gall bladder wall, apparently by making the serosal smooth muscle fibers contract. Active NaCl transport can carry water against osmotic gradients of up to two atmospheres. Under passive conditions water may also move against its activity gradient in the presence of a permeating solute. The significance of water movement against osmotic gradients during active solute transport is discussed.

RESPONSE OF ISOLATED RABBIT ARTICULAR AND EPIPHYSEAL CHONDROCYTES TO RAT LIVER SOMATOMEDIN

1975 ◽  
Vol 66 (1) ◽  
pp. 71-78 ◽  
Author(s):  
PATRICIA ASH ◽  
M. J. O. FRANCIS
Keyword(s):  
Rat Liver ◽  
Articular Chondrocytes ◽  
Hormonal Control ◽  
Thymidine Uptake ◽  
New Bone Formation ◽  
Growth Plate Chondrocytes ◽  
Growth Cartilage ◽  
Graded Response ◽  
Stimulation Of

SUMMARY Isolated rat liver, when perfused with medium containing bovine growth homone produced somatomedin-like activity (liver somatomedin). Liver somatomedin is useful in studies of the hormonal control of the cartilage plate in vitro, since unlike serum it is not contaminated with other hormones or growth factors (apart from growth hormone). Chondrocytes isolated from various regions of the growth cartilage responded differently to liver somatomedin; proliferative chondrocytes, like those isolated from the articular cartilage, showed increased [3H]thymidine uptake in response to liver somatomedin, whereas hypertrophic chondrocytes did not respond. It is suggested that there is a reduction in the response to somatomedin by growth plate chondrocytes as they pass from the proliferative to the hypertrophic state. Thyroxine, thought to be involved in the processes of hypertrophy and new bone formation, did not directly affect [3H]thymidine uptake by proliferative chondrocytes, but inhibited stimulation of their activity by liver somatomedin. Measurement of [3H]thymidine uptake by isolated articular chondrocytes may provide a useful assay for both liver and serum somatomedin. The graded response of chondrocytes to increasing concentrations of liver somatomedin paralleled the response to increasing levels of serum somatomedin.

Heparin Induces Synthesis and Secretion of Tissue Factor Pathway Inhibitor from Endothelial Cells In Vitro

2000 ◽  
Vol 83 (06) ◽  
pp. 937-943 ◽  
Author(s):  
Birgit Svensson ◽  
Randi Olsen ◽  
Mirella Ezban ◽  
Bjarne Østerud ◽  
Ruth Paulssen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Surface Membrane ◽  
Molecular Size ◽  
Fold Increase ◽  
Coagulation System ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Stimulation Of

SummaryTFPI is a potent inhibitor of the extrinsic coagulation system constitutively synthesized by endothelial cells. A major portion of intravascular TFPI is stored associated with endothelial cells, and administration of unfractionated heparin (UFH) in vivo causes a prompt mobilization of TFPI into the circulation. The present study was conducted to investigate how UFH affected the synthesis, secretion and anticoagulant potency of TFPI in endothelial cells in vitro. A spontaneously transformed immortal endothelial cell line was used (ECV304). Stimulation of ECV304 cells with UFH caused a prompt dose-dependent (0-5 IU UFH/ml) release of TFPI to the medium accompanied by no change of TFPI at the surface membrane assessed by immunocytochemical methods. Northern blot analysis revealed two mRNA transcripts for TFPI with a molecular size of 1.4 kb and 4.4 kb, respectively. Stimulation of ECV304 cells for 24 hrs with various concentrations of UFH caused a dose-dependent increase of TFPI in the medium (6.2-29.6 ng/106 cells within the concentration range 0-10 IU/ml). A similar dose-dependent increase in the expression of both TFPI mRNA species was observed. Long-term incubation of ECV304 cells with 5.0 IU/ml UFH caused a 5-10 fold increase in the TFPI concentration accumulated in the medium over 48 hrs. The increased TFPI mRNA expression induced by UFH appeared already after 10 min, peaked after 2-4 hrs, remained augmented throughout the entire period of UFH exposure, and preceeded the synthesis-dependent increase in TFPI release by 2-4 hrs. The procoagulant activity of the cells was downregulated by 36 % and the contribution of TFPI to the anticoagulant potency of ECV304 cells was moderately increased after 24 hrs heparin stimulation. It is suggested that these mechanisms are of major importance for the anticoagulant function of heparins.

scholarly journals Variables Affecting In Vivo Performance of High-Capacity Adenovirus Vectors

2002 ◽  
Vol 76 (4) ◽  
pp. 1600-1609 ◽  
Author(s):  
Gudrun Schiedner ◽  
Sabine Hertel ◽  
Marion Johnston ◽  
Volker Biermann ◽  
Volker Dries ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Transfer ◽  
High Capacity ◽  
Fold Increase ◽  
Expression Cassette ◽  
Matrix Attachment Region ◽  
Hepatic Expression ◽  
Vector Genome

ABSTRACT In high-capacity adenovirus (HC-Ad) vectors the size and/or composition of the vector genome influences vector stability during production and the expression profile following gene transfer. Typically, an HC-Ad vector will contain both a gene or an expression cassette and stuffer DNA that is required to balance the final vector genome to a size of between 27 and 36 kb. To gain an improved understanding of factors that may influence gene expression from HC-Ad vectors, we have generated a series of vectors that carry different combinations of human alpha-1 antitrypsin (hAAT) expression constructs and stuffer DNAs. Expression in vitro did not predict in vivo performance: all vectors expressed hAAT at similar levels when tested in cell culture. Hepatic expression was evaluated following in vivo gene transfer in C57BL/6J mice. hAAT levels obtained from genomic DNA were significantly higher than levels achieved with small cDNA expression cassettes. Expression was independent of the orientation and only marginally influenced by the location of the expression cassette within the vector genome. The use of lambda stuffer DNA resulted in low-level but stable expression for at least 3 months when higher doses were applied. A potential matrix attachment region element was identified within the hAAT gene and caused a 10-fold increase in expression when introduced in an HC-Ad vector genome carrying a phosphoglycerate kinase (pgk) hAAT cDNA construct. We also illustrate the influence of the promoter on anti-hAAT antibody formation in C57BL/6J mice: a human cytomegalovirus but not a pgk promoter resulted in an anti-hAAT antibody response. Thus, the overall design of HC-Ad vectors may significantly influence amounts and duration of gene expression at different levels.

Hormonal control of chloride transport across locust rectum

1978 ◽  
Vol 56 (8) ◽  
pp. 1879-1882 ◽  
Author(s):  
J. Spring ◽  
J. Hanrahan ◽  
J. Phillips
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Fold Increase ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Hormonal Control ◽  
Net Flux ◽  
Hemolymph Volume ◽  
Camp Levels

Rates of ion transport across locust recta were monitored in vitro by following fluxes of 22Na+ and 36Cl−, short-circuit current (Isc), and open-circuit electropotential difference (PD) across this epithelium for several hours. Corpora cardiaca (CC) homogenates, cAMP, theophylline, and hemolymph of recently fed locusts all stimulate electrogenic transport of Cl− across locust rectum, as indicated by a two- to three-fold increase in 36Cl− net flux, Isc, and PD. Cyclic AMP caused a Cl-dependent increase in PD across the lumen-facing but not the hemocoel-facing plasma membrane of the epithelial cells. We propose that a blood-borne factor, possibly from the CC, causes an elevation in cAMP levels in rectal tissue and that this second messenger acts by increasing Cl− entry into the cell from the rectal lumen. Additional fluid absorption accompanies the resulting increase in transport of NaCl, leading to an increase in the hemolymph volume of previously dehydrated locusts.

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