scholarly journals Peripheral O2 chemoreceptors mediate humoral catecholamine secretion from fish chromaffin cells

2003 ◽  
Vol 284 (4) ◽  
pp. R990-R999 ◽  
Author(s):  
Stephen G. Reid ◽  
Steve F. Perry
Keyword(s):  
Oncorhynchus Mykiss ◽  
Chromaffin Cells ◽  
Sodium Cyanide ◽  
Gill Arch ◽  
External Water ◽  
Water Sensing ◽  
First Time ◽  
Cardiorespiratory Reflexes ◽  
Catecholamine Levels ◽  
Stimulation Of

This study addressed the hypothesis that the secretion of catecholamines from trout ( Oncorhynchus mykiss) chromaffin cells, during hypoxia, is triggered by stimulation of O2 chemoreceptors located within the gills. Sodium cyanide was administered into the inspired water (external cyanide) or injected into the gill circulation (internal cyanide) to pharmacologically stimulate external (water sensing) or internal (blood sensing) O2 chemoreceptors, respectively. Both of these treatments caused an elevation of circulating catecholamine levels. The response to external, but not internal, cyanide was abolished by removal of the first gill arch. Hypoxia produced an increase in circulating catecholamine levels that was unaffected by removal of the first gill arch or by denervation of the pseudobranch. Cyanide and hypoxia both caused the well-documented cardiorespiratory reflexes normally observed in this species. This study demonstrates, for the first time, that gill O2chemoreceptors can initiate the reflex that leads to catecholamine release from the chromaffin cells and that stimulation of internally oriented O2 receptors on all gill arches appears to be the physiologically important mechanism for initiating release.

The mechanisms of urea transport by early life stages of rainbow trout (Oncorhynchus mykiss)

2000 ◽  
Vol 203 (20) ◽  
pp. 3199-3207 ◽  
Author(s):  
C.M. Pilley ◽  
P.A. Wright
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Urea Transport ◽  
Early Life Stages ◽  
Urea Transporter ◽  
Urea Excretion ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Collecting Ducts ◽  
External Water ◽  
Very High

We tested the hypothesis that urea transport in rainbow trout (Oncorhynchus mykiss) embryos is dependent, in part, on a bidirectional urea-transport protein. Acute exposure to phloretin and urea analogs [acetamide, thiourea, 1,(4-nitrophenyl)-2-thiourea] reversibly inhibited urea excretion from the embryos to the external water. Unidirectional urea influx was inhibited by acetamide and thiourea, with IC(50) values of 0.04 and 0.05 mmol l(−1), respectively. Influx of urea from the external water to the embryo tended to saturate at elevated external urea concentrations (V(max)=10.50 nmol g(−1) h(−1); K(m)=2 mmol l(−1)). At very high urea concentrations (20 mmol l(−1)), however, a second, non-saturable component was apparent. These results indicate that urea excretion in trout embryos is dependent, in part, on a phloretin-sensitive facilitated urea transporter similar to that reported in mammalian inner medullary collecting ducts and elasmobranch kidney.

scholarly journals Stimulation of NSF ATPase Activity by α-SNAP Is Required for SNARE Complex Disassembly and Exocytosis

1997 ◽  
Vol 139 (4) ◽  
pp. 875-883 ◽  
Author(s):  
Richard J.O. Barnard ◽  
Alan Morgan ◽  
Robert D. Burgoyne
Keyword(s):  
Amino Acids ◽  
Atpase Activity ◽  
Binding Sites ◽  
Chromaffin Cells ◽  
Secretory Pathway ◽  
Snare Complex ◽  
Vesicular Traffic ◽  
Protein Dissociation ◽  
Terminal Amino ◽  
Stimulation Of

N-ethylmaleimide–sensitive fusion protein (NSF) and α-SNAP play key roles in vesicular traffic through the secretory pathway. In this study, NH2- and COOH-terminal truncation mutants of α-SNAP were assayed for ability to bind NSF and stimulate its ATPase activity. Deletion of up to 160 NH2-terminal amino acids had little effect on the ability of α-SNAP to stimulate the ATPase activity of NSF. However, deletion of as few as 10 COOH-terminal amino acids resulted in a marked decrease. Both NH2-terminal (1–160) and COOH-terminal (160–295) fragments of α-SNAP were able to bind to NSF, suggesting that α-SNAP contains distinct NH2- and COOH-terminal binding sites for NSF. Sequence alignment of known SNAPs revealed only leucine 294 to be conserved in the final 10 amino acids of α-SNAP. Mutation of leucine 294 to alanine (α-SNAP(L294A)) resulted in a decrease in the ability to stimulate NSF ATPase activity but had no effect on the ability of this mutant to bind NSF. α-SNAP (1–285) and α-SNAP (L294A) were unable to stimulate Ca2+-dependent exocytosis in permeabilized chromaffin cells. In addition, α-SNAP (1–285), and α-SNAP (L294A) were able to inhibit the stimulation of exocytosis by exogenous α-SNAP. α-SNAP, α-SNAP (1–285), and α-SNAP (L294A) were all able to become incorporated into a 20S complex and recruit NSF. In the presence of MgATP, α-SNAP (1–285) and α-SNAP (L294A) were unable to fully disassemble the 20S complex and did not allow vesicle-associated membrane protein dissociation to any greater level than seen in control incubations. These findings imply that α-SNAP stimulation of NSF ATPase activity may be required for 20S complex disassembly and for the α-SNAP stimulation of exocytosis.

scholarly journals First record of Schulmanela petruschewskii Shulman, 1948 (Nematoda: Capillariidae) from cultured Rainbow trout (Oncorhynchus mykiss) in Turkey

2010 ◽  
Vol 47 (4) ◽  
pp. 273-275
Author(s):  
Z. Pekmezci ◽  
S. Umur
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
New Record ◽  
Parasite Species ◽  
Liver Parenchyma ◽  
First Record ◽  
Parasite Fauna ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
First Time ◽  
North Latitude

AbstractThe nematode Schulmanela petruschewskii (Shulman, 1948) was identified during the parasitological examination on the liver parenchyma in one specimens of a cultured rainbow trout (Oncorhynchus mykiss) which reared in Derbent Dam Lake in Samsun, Turkey (41°25′6′’ North latitude, 35°49′52′’ East longitude) in August 2008. This parasite species was not previously reported from Turkey. With the present study we report S. petruschewskii for the first time in Turkey. This specimen which is a parasite of cultured rainbow trout (Oncorhynchus mykiss) is a new record for the Turkish parasite fauna. Original measurements and figures are presented.

Insulin and insulin-like growth factor I signaling pathways in rainbow trout (Oncorhynchus mykiss) during adipogenesis and their implication in glucose uptake

2010 ◽  
Vol 299 (1) ◽  
pp. R33-R41 ◽  
Author(s):  
L. Bouraoui ◽  
E. Capilla ◽  
J. Gutiérrez ◽  
I. Navarro
Keyword(s):  
Rainbow Trout ◽  
Growth Factor ◽  
Oncorhynchus Mykiss ◽  
Glucose Uptake ◽  
Signaling Pathways ◽  
Mapk Phosphorylation ◽  
Factor I ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Igf I ◽  
Stimulation Of

Primary cultures of rainbow trout ( Oncorhynchus mykiss ) adipocytes were used to examine the main signaling pathways of insulin and insulin-like growth factor I (IGF-I) during adipogenesis. We first determined the presence of IGF-I receptors (IGF-IR) and insulin receptors (IR) in trout preadipocytes ( day 5) and adipocytes ( day 14). IGF-IRs were more abundant and appeared to be in higher levels in differentiated cells than in preadipocytes, whereas IRs were detected in lower but constant levels throughout the culture. The cells were immunoreactive against ERK1/2 MAPK, and AKT/PI3K, components of the two main signal transduction pathways for insulin and IGF-I receptors. Stimulation of MAPK phosphorylation by IGF-I was higher in preadipocytes than in adipocytes, while no effects were observed in MAPK phosphorylation after incubation of cells with insulin. AKT phosphorylation increased in the presence of both insulin and IGF-I, with higher levels of stimulation in adipocytes than in preadipocytes. Activation of both pathways was blocked by the use of specific inhibitors of MAPK (PD98059) and AKT (wortmannin). We describe here, for the first time, the effects of IGF-I and insulin on 2-deoxyglucose uptake in primary culture of trout adipocytes. IGF-I was more potent in stimulating glucose uptake than insulin, and PD98059 and wortmannin inhibited the stimulation of glucose uptake by this growth factor, suggesting that IGF-I plays an important metabolic role in trout adipocytes. Our results suggest that differential activation of the MAPK and AKT pathways are involved in the IGF-I- and insulin-induced effects of trout adipocytes during the various stages of adipogenesis.

Plasma and organ catecholamine levels following stimulation of the rat insular cortex

1992 ◽  
Vol 569 (2) ◽  
pp. 221-228 ◽  
Author(s):  
Stephen M. Oppenheimer ◽  
Tarek M. Saleh ◽  
John X. Wilson ◽  
avid F. Cechetto
Keyword(s):  
Insular Cortex ◽  
Catecholamine Levels ◽  
Stimulation Of

First Multistage Hydraulic Fracturing in Russian Offshore: Integrated Approach to Completion and Stimulation of Apt Deposits of V.Filanovsky Field

2021 ◽  
Author(s):  
Mikhail Yurievich Golenkin ◽  
Denis Vladimirovich Eliseev ◽  
Alexander Anatolyevich Zemchikhin ◽  
Alexey Alexandrovich Borisenko ◽  
Akhmat Sakhadinovich Atabiyev ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Caspian Sea ◽  
Complex Type ◽  
The Caspian Sea ◽  
Multistage Hydraulic Fracturing ◽  
Coiled Tubing ◽  
Sand Control ◽  
Friction Reducing ◽  
First Time ◽  
Stimulation Of

Abstract The paper describes the results of the first multistage hydraulic fracturing operations in Russia on the Caspian Sea shelf in the gas condensate and oil deposits of the Aptian formation of V. Filanovsky field. In addition to the small productive formation depth, long horizontal sections with a complex trajectory and high collapse gradients due to large zenith angles when passing the Albian and Aptian deposits of poorly consolidated sandstones are an additional challenge for choosing a multistage hydraulic fracturing assembly. The above features require the use of modern sand control screens with enhanced frac sleeves. A design was developed which includes frac sleeves and sand control screens that can withstand multiple cycles of hydraulic impact during hydraulic fracturing, as well as many opening/closing cycles. A seawater-based frac fluid system was applied. The frac fleet was located on a pontoon, the coiled tubing – on a platform. For the first time in Russia, a 2-5/8 inch coiled tubing with a complex-type friction reducing system was used to switch coupling/sleeves in conditions of very long horizontal sections, complex trajectories, and high friction coefficients. The minimum distances between the screen's sliding sleeves and frac sleeves did not prevent from performing manipulations in complex environment. For well cleaning, the frac assemblies of reverse rotary-pulse and rotary-directional types were used. At the first stage of the project, the development of an optimal method of well completion was successfully implemented. Due to the close interaction of the operating company, service company, and science & engineering team of the operator, for the first time in Russia the design of downhole equipment with the use of advanced technologies of sand control screens, frac sleeves was presented. This solution has proved its effectiveness – the downhole equipment has retained its operational properties after a long period of well operation and further in the process of hydraulic fracturing. At the second stage of the project, 32 MSHF operations were performed at four wells. To reduce nonproductive time and operational risks, a satellite communication complex was additionally deployed on the pontoon to join the engineering centers of Astrakhan, Moscow, and Houston. After finishing the well development, the design indicators for formation fluid rates were achieved, which proved the effectiveness of the stimulation of the field's target objects – this opens great prospects for further development of low-permeability reservoirs at offshore sites in the Caspian Sea. The successful project implementation and the achievement of the design values of oil flow rates has expanded the possibilities of commercial operation of the low-permeable Aptian formation, complicated by the presence of a gas cap and underlying water. A solution was presented for working in extended horizontal well sections with 2-5/8 inch coiled tubing together with a complex-type mechanical friction reducing system. The economic effect was achieved when solving tasks of manipulating mechanical screen couplings and frac port sleeves without the involvement of downhole tractors. The use of new solutions in the completion assembly made it possible to eliminate additional sand ingress problems.

scholarly journals Reflex cardiorespiratory events from esophageal origin are heightened by preterm birth

2017 ◽  
Vol 123 (2) ◽  
pp. 489-497 ◽  
Author(s):  
Stéphanie Nault ◽  
Nathalie Samson ◽  
Charlène Nadeau ◽  
Djamal Djeddi ◽  
Jean-Paul Praud
Keyword(s):  
Preterm Birth ◽  
Arterial Pressure ◽  
Random Order ◽  
Neonatal Infection ◽  
Full Term ◽  
Simultaneous Stimulation ◽  
C Fibers ◽  
C Fiber ◽  
Cardiorespiratory Reflexes ◽  
Stimulation Of

The involvement of gastroesophageal refluxes in cardiorespiratory events of preterm infants remains controversial. While a few studies in full-term newborn animals have shown that stimulation of esophageal receptors leads to cardiorespiratory reflexes, the latter remain largely unknown, especially after premature birth. The present study aimed to 1) characterize the cardiorespiratory reflexes originating from esophageal receptors in newborn lambs and 2) test the hypotheses that preterm birth enhances reflex cardiorespiratory inhibition and that C-fibers are involved in these reflexes. Eight full-term lambs and 10 lambs born 14 days prematurely were studied. Following surgical instrumentation, a 6-h polysomnography was performed without sedation to record electrocardiogram, respiratory movements, arterial pressure, laryngeal constrictor muscle activity, state of alertness, and hemoglobin oxygen saturation. Five esophageal stimulations of the upper and/or lower esophagus, including rapid balloon inflation and/or HCl injection, were performed in random order. A second recording was performed in full-term lambs 24 h later, after C-fiber blockade by capsaicin. Results confirmed that esophageal stimulations induced inhibitory cardiorespiratory reflexes combined with protective mechanisms, including laryngeal closure, swallowing, coughing, increased arterial pressure, and arousal. Preterm birth heightened cardiorespiratory inhibition. The strongest cardiorespiratory inhibition was observed following simultaneous stimulation of the lower and upper esophagus. Finally, cardiorespiratory inhibition was decreased after C-fiber blockade. In conclusion, esophageal stimulation induces inhibitory cardiorespiratory reflexes, which are partly mediated by C-fibers and more pronounced in preterm lambs. Clinical relevance of these findings requires further studies, especially in conditions associated with increased cardiorespiratory events, e.g., neonatal infection. NEW & NOTEWORTHY Preterm birth heightens the cardiorespiratory events triggered by esophageal stimulation. The most extensive cardiorespiratory events are induced by simultaneous stimulation of the proximal and distal esophagus.

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