scholarly journals GLUCOSE METABOLISM BY SEA RAVEN (HEMITRIPTERUS AMERICANUS) AND RAINBOW TROUT (ONCORHYNCHUS MYKISS) ERYTHROCYTES

1994 ◽  
Vol 194 (1) ◽  
pp. 167-180 ◽  
Author(s):  
D Sephton ◽  
W Driedzic

The fate of extracellular glucose in blood isolated from sea raven (Hemitripterus americanus) and rainbow trout (Onchorhynchus mykiss) was determined. In blood from both species incubated in vitro at low physiological pH, the decrease in plasma glucose concentration was more than adequate to support oxygen consumption. Glucose disappearance could not be accounted for by increases in lactate, red blood cell (RBC) glucose or RBC glycogen concentrations. Rates of 14CO2 production from [6-14C]glucose over a 2 h incubation period were less than 1 % of metabolic rate. Only small amounts of label appeared in RBC protein, lipid or glycogen fractions relative to metabolic rates, but label accumulated in the intracellular acid-soluble fraction (presumably free glucose, glycolytic intermediates, amino acids, citric acid cycle intermediates, etc.) at rates consistent with oxygen consumption and glucose disappearance. The simplest explanation for the mismatch between 14CO2 production and the other estimates of metabolic rate is that incubation times were too short for equilibration to occur. A consequence is that studies of this nature cannot use 14CO2 production to elucidate rates of aerobic fuel utilization. By default, the data imply that glucose serves as a primary aerobic metabolic fuel for the RBCs, at least under some conditions.

2012 ◽  
Vol 90 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Jon Christian Svendsen ◽  
John Fleng Steffensen ◽  
Kim Aarestrup ◽  
Michael Frisk ◽  
Anne Etzerodt ◽  
...  

Under certain conditions, a number of fish species may perform brief excursions into severe hypoxia and return to water with a higher oxygen content. The term severe hypoxia describes oxygen conditions that are below the critical oxygen saturation (Scrit), defined here as the oxygen threshold at which the standard metabolic rate becomes dependent upon the ambient oxygen content. Using rainbow trout ( Oncorhynchus mykiss (Walbaum, 1792), this study quantified the excess posthypoxic oxygen consumption (EPHOC) occurring after exposure to oxygen availability below Scrit. Tests showed that Scrit was 13.5% air saturation (O2sat). Fish were exposed to 10% O2sat for 0.97 h, and the EPHOC was quantified in normoxia (≥95% O2sat) and hypoxia (30% O2sat) to test the hypothesis that reduced oxygen availability would decrease the peak metabolic rate (MO2peak) and prolong the duration of the metabolic recovery. Results showed that MO2peak during the recovery was reduced from 253 to 127 mg O2·kg–1·h–1 in hypoxia compared with normoxia. Metabolic recovery lasted 5.2 h in normoxia and 9.8 h in hypoxia. The EPHOC, however, did not differ between the two treatments. Impeded metabolic recovery in hypoxia may have implications for fish recovering from exposure to oxygen availability below Scrit.


1991 ◽  
Vol 156 (1) ◽  
pp. 139-151 ◽  
Author(s):  
B. L. TUFTS ◽  
R. G. BOUTILIER

Experiments were carried out to investigate the relationship between ion exchange and energy metabolism in rainbow trout erythrocytes in vitro. Under resting conditions, the sodium/potassium pump accounts for 20 % of the cellular energy budget. In the presence of the β-adrenergic agonist isoproterenol, however, this increases to 43 %. Inhibition of the sodium/potassium pump with ouabain results in greater increases in erythrocyte water content and sodium and chloride concentrations and a greater decrease in erythrocyte potassium concentration following stimulation by isoproterenol. Moreover, the decrease in erythrocyte NTP levels observed following adrenergic stimulation does not occur when the sodium/potassium pump is inhibited with ouabain. Inhibition of the sodium/potassium pump also abolishes the increase in oxygen consumption by the cells which normally takes place following adrenergic stimulation. Finally, depletion of erythrocyte NTP levels by the sodium ionophore monensin or by previous incubation with nitrogen does not result in a significant increase in oxygen consumption. Thus, catecholamines appear to be crucial for the metabolic-membrane coupling that occurs following adrenergic stimulation in rainbow trout erythrocytes.


2019 ◽  
Vol 207 ◽  
pp. 43-51 ◽  
Author(s):  
Richard C. Kolanczyk ◽  
Jeffrey S. Denny ◽  
Barbara R. Sheedy ◽  
Patricia K. Schmieder ◽  
Mark A. Tapper

1996 ◽  
Vol 109 (3) ◽  
pp. 569-578 ◽  
Author(s):  
H. Herrmann ◽  
M.D. Munick ◽  
M. Brettel ◽  
B. Fouquet ◽  
J. Markl

We have isolated from a rainbow trout (Oncorhynchus mykiss) spleen cDNA library a clone coding for vimentin. The deduced amino acid sequence reveals a high degree of identity with vimentin from carp (81%), frog (71%), chick and human (73% each). Large stretches in the central alpha-helical rod are identical within all four classes of vertebrates, but in 17 residues spread over the entire rod, the two fish differ distinctly from the tetrapod species. In addition, in the more diverged non-helical head domain, a nonapeptide motif previously shown to be important for regular filament formation is conserved. Recombinant trout vimentin assembles into bona fide filaments in vitro, with a temperature optimum between 18 and 24 degrees C. Above 27 degrees C, however, filament assembly is abruptly abolished and short filaments with thickened ends as well as structures without typical intermediate filament appearance are formed. This distinguishes its assembly properties significantly from amphibian, avian and mammalian vimentin. Also in vivo, after cDNA transfection into vimentin-free mammalian epithelial cells, trout vimentin does not form typical intermediate filament arrays at 37 degrees C. At 28 degrees C, and even more pronounced at 22 degrees C, the vimentin-positive material in the transfected cells is reorganized in the perinuclear region with a partial fibrillar appearance, but typical intermediate filament arrays are not formed. Together with immunoblotting and immunolocalization data from trout tissues, where vimentin is predominantly found in glial and white blood cells, we conclude that vimentin is indeed important in its filamentous form in fish and other vertebrates, possibly fulfilling cellular functions not directly evident in gene targeting experiments carried out in mice.


Author(s):  
Lyudmyla Buyun ◽  
Oleksandr Gyrenko ◽  
Maryna Opryshko ◽  
Lyudmyla Kovalska ◽  
Halyna Tkachenko ◽  
...  

This research aimed to evaluate the in vitro effect of buffer extract obtained from leaves and pseudobulbs (modified shoots) of Dendrobium parishii Rchb. f. on the 2-thiobarbituric acid reactive substances (TBARS) as lipid peroxidation biomarker, aldehydic and ketonic derivatives of oxidatively modified proteins, and total antioxidant capacity (TAC) in the muscle tissue of the rainbow trout (Oncorhynchus mykiss Walbaum). The shoots (pseudobulbs) with leaves of Dendrobium parishii cultivated under glasshouse conditions were sampled at M.M. Gryshko National Botanic Garden (NBG) (Kyiv, Ukraine). Since 1999, the whole collection of tropical and subtropical plants (including orchids) has had the status of a National Heritage Collection of Ukraine and is supported through State funding. Besides, NBG’s collection of tropical orchids was registered at the Administrative Organ of CITES in Ukraine (Ministry of Environment Protection, registration No. 6939/19/1-10 of 23 June 2004). The collected pseudobulbs and leaves were brought into the laboratory for biochemical studies. Freshly collected leaves were washed, weighed, crushed, and homogenized in 0.1M phosphate buffer (pH 7.4) (in proportion 1:19, w/w) at room temperature. The extract was then filtered and investigated for its antioxidant capacity. The extract was stored at -20°C until use. The increase in TBARS level in the muscle tissue exposed to extracts derived from leaves and pseudobulbs of D. parishii was insignificant. The level of ketonic derivatives of oxidatively modified proteins was non-significantly decreased both for leaf and pseudobulb extracts compared to the untreated samples. The extracts obtained from leaves and pseudobulbs of D. parishii significantly increased the TAC level in muscle tissue due to inhibited the Fe2+/ascorbate-induced oxidation of Tween 80. Overall, these findings demonstrate that aqueous extracts of vegetative organs of Dendrobium parishii can enhance the total antioxidant capacity in the muscle tissue of the rainbow trout. Moreover, this antioxidant effect was more intensive for pseudobulb extracts.


2000 ◽  
Vol 278 (4) ◽  
pp. R956-R963 ◽  
Author(s):  
Jean-Michel Weber ◽  
Deena S. Shanghavi

The rate of hepatic glucose production (Ra glucose) of rainbow trout ( Oncorhynchus mykiss) was measured in vivo by continuous infusion of [6-3H]glucose and in vitro on isolated hepatocytes to examine the role of epinephrine (Epi) in its regulation. By elevating Epi concentration and/or blocking β-adrenoreceptors with propranolol (Prop), our goals were to investigate the mechanism for Epi-induced hyperglycemia to determine the possible role played by basal Epi concentration in maintaining resting Ra glucose and to assess indirect effects of Epi in the intact animal. In vivo infusion of Epi caused hyperglycemia (3.75 ± 0.16 to 8.75 ± 0.54 mM) and a twofold increase in Ra glucose (6.57 ± 0.79 to 13.30 ± 1.78 μmol ⋅ kg− 1 ⋅ min− 1, n = 7), whereas Prop infusion decreased Ra from 7.65 ± 0.92 to 4.10 ± 0.56 μmol ⋅ kg− 1 ⋅ min− 1( n = 10). Isolated hepatocytes increased glucose production when treated with Epi, and this response was abolished in the presence of Prop. We conclude that Epi-induced trout hyperglycemia is entirely caused by an increase in Ra glucose, because the decrease in the rate of glucose disappearance normally seen in mammals does not occur in trout. Basal circulating levels of Epi are involved in maintaining resting Ra glucose. Epi stimulates in vitro glucose production in a dose-dependent manner, and its effects are mainly mediated by β-adrenoreceptors. Isolated trout hepatocytes produce glucose at one-half the basal rate measured in vivo, even when diet, temperature, and body size are standardized, and basal circulating Epi is responsible for part of this discrepancy. The relative increase in Ra glucose after Epi stimulation is similar in vivo and in vitro, suggesting that indirect in vivo effects of Epi, such as changes in hepatic blood flow or in other circulating hormones, do not play an important role in the regulation of glucose production in trout.


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