Respiratory and Circulatory Responses to Hypoxia in the Lobster Homarus Americanus

1975 ◽  
Vol 62 (3) ◽  
pp. 637-655 ◽  
Author(s):  
B. R. MCMAHON ◽  
J. L. WILKENS
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Homarus Americanus ◽  
Control Mechanisms ◽  
Blood Oxygen ◽  
Experimental Conditions ◽  
Oxygen Levels ◽  
Wide Range ◽  
Oxygen Tensions

Contrary to previous reports, oxygen consumption is maintained over a wide range of external oxygen tensions in the lobster Homarus americanus. In animals acclimated to the experimental conditions this response is mediated by increased branchial pumping, increased effectiveness of oxygen uptake by the gills and an increased contribution by the respiratory pigment to the oxygen delivered to the tissues. Circulatory blood oxygen levels are generally high in lobsters resting in well-aerated water. Mechanisms for detection of hypoxia and possible control mechanisms are discussed.

Simultaneous apnoea and bradycardia in the lobster Homarus americanus

1972 ◽  
Vol 50 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Brian R. McMahon ◽  
Jerrel L. Wilkens
Keyword(s):  
Homarus Americanus ◽  
Normal Activity ◽  
Control Area ◽  
Central Control ◽  
Blood Oxygen ◽  
Mediating Effects ◽  
Experimental Conditions ◽  
Oxygen Tensions

Periods of simultaneous apnoea and bradycardia lasting for up to 20 min have been recorded from specimens of Homarus americanus isolated under experimental conditions but otherwise exposed to no direct stress. The onset of the response and the resumption of normal activity occurred abruptly and simultaneously in both respiratory and circulatory parameters. A study of the response leads the authors to propose a central control area which can inhibit both branchial and cardiac pumps simultaneously. Blood oxygen tensions were monitored during the response and possible mediating effects of oxygen are discussed.

Effect of hemorrhagic hypotension on oxygen consumption of dogs

1964 ◽  
Vol 207 (3) ◽  
pp. 647-649 ◽  
Author(s):  
Elvin E. Smith ◽  
Jack W. Crowell
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Arterial Pressure ◽  
Flow Rate ◽  
Blood Oxygen ◽  
Oxygen Utilization ◽  
Epinephrine Administration ◽  
Utilization Coefficient ◽  
Subsequent Rise

The effects of hematocrit, Dibenzyline, and epinephrine on oxygen consumption were studied in 220 dogs whose arterial pressure was lowered to and maintained at 30 mm Hg. Oxygen consumption was recorded previous to and during the period of hypotension. The average oxygen consumption was 7.20 ml/kg min prior to hemorrhage. Ten minutes after hemorrhage the oxygen consumption was 3.58 ml/kg min (50% of control). After 30 min of hypotension the oxygen consumption was 4.70 ml/kg min (65% of control), and the oxygen consumption increased to 5.33 ml/kg min (74% of control) after 1 hr. Pretreatment with Dibenzyline increased the oxygen consumption during the early stages of hypotension but had little effect in the latter stages. Epinephrine administration decreased the oxygen consumption during the entire hypotensive period. Previous studies have shown that the oxygen utilization coefficient approaches its maximal value during the hypotensive period; therefore, oxygen uptake becomes limited by the blood flow and the changes in oxygen consumption indicate changes in flow rate to active tissue. Simultaneous studies showed that the hematocrit influenced oxygen transport by effects on both the blood oxygen content and the blood flow. The results illustrate that animals with hematocrits of 35–39 are able to transport more oxygen than animals with other hematocrits. Evidence is presented to show that the initial fall and the subsequent rise in oxygen consumption during hypotension may be a local autoregulation of blood flow.

Respiration of Artemia franciscana cultured under different salinities

2011 ◽  
Vol 61 (4) ◽  
pp. 413-425 ◽  
Author(s):  
Mona M. El-Gamal
Keyword(s):  
Oxygen Consumption ◽  
Brine Shrimp ◽  
Developmental Stages ◽  
External Medium ◽  
Artemia Franciscana ◽  
Uptake Rates ◽  
Wide Range ◽  
Brine Shrimps ◽  
Consumption Rates ◽  
Oxygen Tensions

AbstractThe available studies on oxygen consumption by Artemia related to different salinities reported contradictory results. However, most of these studies have been obtained only for newly hatched nauplii or adults, and have neglected the gradual accommodation that gives a picture about what really happens in nature. In order to face the problems noted above individuals of Artemia franciscana were acclimated to four different salinities (25 g/L, 35 g/L, 70 g/L and 120 g/L) under laboratory conditions. The oxygen consumption under declining oxygen tensions (Po 2) for each of the 19 stages in Artemia life metamorphic developments was examined. The brine shrimp under different salinities is a respiratory regulator over a wide range of Po 2's. Oxygen consumption rates varied across the salinities with a general inverse relationship in uptake rates versus salinity. The brine shrimps' individual weight significantly decreased with increasing salt concentration of the external medium. Generally, regulation of oxygen consumption improved with development. Specimens cultured under high salinities (70 g/L and 120 g/L) started the regulation earlier than low salinities, even before heart and gill formation (in stage 2) and high salinities also accelerated the development of the heart and the gut earlier than those cultured under lower salinities (stage 3 instead of 6). Later developmental stages did not perform osmotical work in the same manner as nauplii did (0-6) and oxygen consumption did not drive the ionic regulation of Artemia franciscana specimens cultured under different salinities.

EFFECTS OF LONG-TERM TREATMENT AND OF LOW CONCENTRATIONS OF THYROID HORMONES ON THE OXYGEN UPTAKE OF TOAD TISSUES

1966 ◽  
Vol 36 (3) ◽  
pp. 221-229 ◽  
Author(s):  
C. C. THORNBURN ◽  
A. J. MATTY
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Bufo Bufo ◽  
Term Treatment ◽  
Seasonal Effect ◽  
Long Term Treatment ◽  
Wide Range ◽  
Two Peaks

SUMMARY Isolated tissues of the toad Bufo bufo (urinary bladder, skin and kidney) were treated in vitro with thyroxine (T4) or tri-iodothyronine (T3) both with and without prior administration of the hormones in vivo. They were incubated at low temperature, and their oxygen consumption studied for 48 hr. Both hormones had little effect in vitro. Pretreatment with T4 in vivo usually lowered oxygen uptake; the effect of pretreatment with T3 varied. The presence of alanine in the incubating medium caused a marked increase in oxygen consumption. A seasonal effect was also found. The respiration of isolated toad bladder was stimulated by a wide range of concentrations of thyroxine in vitro, and there were two peaks of stimulation.

Is Oxygen Consumption of Surviving Tissues Determined by the Oxygen Tension of the Suspension Medium?

1978 ◽  
Vol 33 (7-8) ◽  
pp. 511-516
Author(s):  
Josef Peter Pichotka ◽  
Hans Josef Schmidt
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Gas Phase ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Fluid Phase ◽  
Tissue Samples ◽  
Suspension Medium ◽  
Measuring Period ◽  
Oxygen Tensions

Abstract Oxygen tension in the suspension medium and oxygen uptake of the isolated diaphragm of the mouse have been determined simultaneously with systematic variation of shaking frequency and oxygen concentration of the gas phase. Oxygen tension in the suspension medium readies its final value during the usual equilibration period of 10 minutes and remains constant for the whole measuring period. Each combination of shaking frequency and oxygen concentration of the gas phase results in a reproducible value of oxygen tension in the medium. Equal oxygen tension in the fluid phase can be attained by different combinations of shaking frequency and oxygen concentration of the gas phase. Oxygen uptake at the same oxygen tension of the suspension medium can be very different; it is the higher the higher the shaking rate in the combination. On the other hand the same oxygen consumption of the tissue samples can be observed with highly different oxygen tensions in the medium. It must be concluded from the data in this paper, that the influence of shaking rate per se on the oxygen uptake of isolated tissue can be of the same order as the influence of oxygen tension.

RELATION OF OXYGEN UPTAKE TO BODY WEIGHT OF RATS AT DIFFERENT ENVIRONMENTAL TEMPERATURES

1965 ◽  
Vol 43 (3) ◽  
pp. 351-357 ◽  
Author(s):  
N. T. Gridgeman ◽  
O. Heroux
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Statistical Analysis ◽  
Oxygen Uptake ◽  
Linear Relation ◽  
Environmental Temperature ◽  
Analysis Of Covariance ◽  
Sprague Dawley ◽  
Experimental Conditions ◽  
Environmental Temperatures

Statistical analysis of data on the oxygen consumption of rats (Sprague–Dawley strain; records covering several years of experimentation in one laboratory) indicated that the relation between oxygen uptake and body weight is not constant. Kleiber's case for a linear relation between oxygen uptake and the [Formula: see text] power of body weight for homeotherms in general under normal environmental conditions is not impugned by the present findings. Under abnormal experimental conditions, particularly as regards environmental temperature, the use of the analysis of covariance is recommended to best allow for the effect of body weight on oxygen uptake.

Effects of temperature on ileal blood flow and oxygenation

1985 ◽  
Vol 249 (2) ◽  
pp. G246-G249
Author(s):  
P. R. Kvietys ◽  
S. L. Harper ◽  
R. J. Korthuis ◽  
D. N. Granger
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Arterial Pressure ◽  
Venous Outflow ◽  
Profound Influence ◽  
Wide Range ◽  
Effects Of Temperature ◽  
Oxygen Difference ◽  
Venous Outflow Pressure

Arterial pressure, venous outflow pressure, blood flow, and arteriovenous oxygen difference were measured in autoperfused preparations of canine ileum while lumen temperature was altered in 1–5 degrees C increments (or decrements) between 31 and 40 degrees C. Neither blood flow nor vascular resistance was correlated to lumen temperature. However, both arteriovenous oxygen difference and oxygen uptake were linearly correlated with lumen temperature. The relation between ileal oxygen uptake and lumen temperature was consistent with a change in metabolic rate for a 10 degrees C change in temperature (Q10) for oxygen consumption of 2.7. These observations indicate that ambient temperature exerts a profound influence on intestinal oxygen consumption and that variations in temperature may explain the wide range of intestinal oxygen uptake values reported in the literature.

A Re-Investigation of Metabolic Gradients

1930 ◽  
Vol 7 (3) ◽  
pp. 260-268
Author(s):  
C. SHEARER
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Conclusive Evidence ◽  
Wide Range

1. The oxygen consumption of planarians has been investigated by means of the Haldane manometer with a view to determining the presence of a metabolic gradient. 2. The oxygen uptake was found to vary over a wide range. It is concluded that this is largely conditioned by the degree of movement exhibited by the animals during an experiment. 3. No conclusive evidence for the presence of a metabolic gradient could be obtained. 4. On general physiological grounds reasons have been put forward for doubting the presence of such a gradient.

The biochemistry of drugs and doping methods used to enhance aerobic sport performance

2008 ◽  
Vol 44 ◽  
pp. 63-84 ◽  
Author(s):  
Chris E. Cooper
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Content ◽  
Oxygen Delivery ◽  
Sport Performance ◽  
Blood Substitutes ◽  
Altitude Training ◽  
Blood Oxygen ◽  
Oxygen Carriers ◽  
Sports Performance ◽  
Blood Doping

Optimum performance in aerobic sports performance requires an efficient delivery to, and consumption of, oxygen by the exercising muscle. It is probable that maximal oxygen uptake in the athlete is multifactorial, being shared between cardiac output, blood oxygen content, muscle blood flow, oxygen diffusion from the blood to the cell and mitochondrial content. Of these, raising the blood oxygen content by raising the haematocrit is the simplest acute method to increase oxygen delivery and improve sport performance. Legal means of raising haematocrit include altitude training and hypoxic tents. Illegal means include blood doping and the administration of EPO (erythropoietin). The ability to make EPO by genetic means has resulted in an increase in its availability and use, although it is probable that recent testing methods may have had some impact. Less widely used illegal methods include the use of artificial blood oxygen carriers (the so-called ‘blood substitutes’). In principle these molecules could enhance aerobic sports performance; however, they would be readily detectable in urine and blood tests. An alternative to increasing the blood oxygen content is to increase the amount of oxygen that haemoglobin can deliver. It is possible to do this by using compounds that right-shift the haemoglobin dissociation curve (e.g. RSR13). There is a compromise between improving oxygen delivery at the muscle and losing oxygen uptake at the lung and it is unclear whether these reagents would enhance the performance of elite athletes. However, given the proven success of blood doping and EPO, attempts to manipulate these pathways are likely to lead to an ongoing battle between the athlete and the drug testers.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

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