scholarly journals Metabolic depression during environmental stress: the role of extracellular versus intracellular pH in Sipunculus nudus

1996 ◽  
Vol 199 (8) ◽  
pp. 1801-1807 ◽  
Author(s):  
A Reipschläger ◽  
H O Pörtner
Keyword(s):  
Oxygen Consumption ◽  
Intracellular Ph ◽  
Body Wall ◽  
Supply And Demand ◽  
Extracellular Ph ◽  
The Body ◽  
Metabolic Depression ◽  
Sipunculus Nudus ◽  
Rate Of Oxygen Consumption ◽  
Body Wall Musculature

Environmental stresses such as hypoxia or hypercapnia are known to cause acid-base disturbances and in several organisms they lead to metabolic depression. The present study was undertaken to quantify the influence of these changes in acid&shyp;base parameters on metabolic rate. We determined the rate of oxygen consumption in a non-perfused preparation of the body wall musculature of the marine worm Sipunculus nudus at various levels of extra- and intracellular pH (pHe and pHi, respectively), PCO2 and [HCO3-]. The acid&shyp;base status of the tissue was modified and clamped by long-term exposure to media set to specific values of extracellular pH, PCO2 and [HCO3-]. At a pHe of 7.90, which is equivalent to the normoxic normocapnic in vivo extracellular pH, and an ambient PCO2 of 0.03 kPa (control conditions), pHi was 7.26±0.02 (mean ± s.d., N=5). A reduction of extracellular pH from 7.90 to 7.20 resulted in a significant decrease of pHi to 7.17±0.05 at 0.03 kPa PCO2 (normocapnia) and to 7.20±0.02 at 1.01 kPa PCO2 (hypercapnia). At the same time, the rate of oxygen consumption of the tissue was significantly depressed by 18.7±4.7 % and 17.7±3.0 %, respectively. A significant depression of oxygen consumption by 13.7±4.7 % also occurred under hypercapnia at pHe 7.55 when pHi was elevated above control values (7.32±0.01). No significant changes in oxygen consumption were observed when pHe was either drastically elevated to 8.70 under normocapnia (pHi 7.36±0.05) or maintained at 7.90 during hypercapnia (pHi 7.37±0.03). ATP and phospho-l-arginine concentrations, as well as the Gibbs free energy change of ATP hydrolysis (dG/dATP), were maintained at high levels during all treatments, indicating an equilibrium between energy supply and demand. We conclude that the depression of aerobic energy turnover in isolated body wall musculature of S. nudus is induced by low extracellular pH. A model is proposed which could explain a reduced ATP cost of pHi regulation during extracellular acidosis, thus contributing to metabolic depression.

scholarly journals A role for adenosine in metabolic depression in the marine invertebrate Sipunculus nudus

1997 ◽  
Vol 272 (1) ◽  
pp. R350-R356 ◽  
Author(s):  
A. Reipschlager ◽  
G. E. Nilsson ◽  
H. O. Portner
Keyword(s):  
Body Wall ◽  
Marine Invertebrate ◽  
Coelomic Fluid ◽  
Metabolic Depression ◽  
O2 Consumption ◽  
Experimental Conditions ◽  
Indwelling Catheter ◽  
Sipunculus Nudus ◽  
Body Wall Musculature ◽  
Concentration Changes

Involvement of neurotransmitters in metabolic depression under hypoxia and hypercapnia was examined in Sipunculus nudus. Concentration changes of several putative neurotransmitters in nervous tissue during anoxic or hypercapnic exposure or during combined anoxia and hypercapnia were determined. Among amino acids (gamma-aminobutyric acid, glutamate, glycine, taurine, serine, and aspartate) and monoamines (serotonin, dopamine, and norepinephrine), some changes were significant, but none were consistent with metabolic depression under all experimental conditions applied. Only the neuromodulator adenosine displayed concentration changes in accordance with metabolic depression under all experimental conditions. Levels increased during anoxia, during hypercapnia, and to an even greater extent during anoxic hypercapnia. Adenosine infusions into coelomic fluid via an indwelling catheter induced a significant depression of the normocapnic rate of O2 consumption from 0.36 +/- 0.04 to a minimum of 0.24 +/- 0.02 (SE) mumol.g-1.h-1 after 90 min (n = 6). Application of the adenosine antagonist theophylline caused a transient rise in O2 consumption 30 min after infusion during hypercapnia but not during normocapnia. Effects of adenosine and theophylline were observed in intact individuals but not in isolated body wall musculature. The results provide evidence for a role of adenosine in inducing metabolic depression in S. nudus, probably through the established effects of decreasing neuronal excitability and neurotransmitter release. In consideration of our previous finding that metabolic depression in isolated body wall musculature was elicited by extracellular acidosis, it is concluded that central and cellular mechanisms combine to contribute to the overall reduction in metabolic rate in S. nudus.

The Oxygen Consumption of an Echiuroid, Bonellia Viridis Rolando

1968 ◽  
Vol 48 (2) ◽  
pp. 427-434
Author(s):  
A. E. BRAFIELD
Keyword(s):  
Oxygen Consumption ◽  
Body Size ◽  
Continuous Flow ◽  
Muscular Activity ◽  
Dry Weight ◽  
The Body ◽  
Body Region ◽  
Rate Of Oxygen Consumption

1. The oxygen consumption of the echiuroid Bonellia viridis has been investigated by means of a continuous-flow polarographic respirometer. 2. The general rate of oxygen consumption per unit dry weight is similar to that characteristic of polychaetes, and declines exponentially with increasing body size. 3. The rate of oxygen consumption rises in the light and falls again if darkness is restored. 4. The oxygen consumption of the isolated proboscis plus that of the isolated body region corresponds closely to that of the entire animal. 5. The oxygen consumption per unit dry weight of the proboscis is considerably higher than that of the body region. 6. The oxygen consumption of an isolated body region increases in the presence of light, but that of an isolated proboscis does not. 7. These findings are discussed in relation to the biology of the animal, observed muscular activity, and the occurrence of the pigment bonellin.

The relationship between cirral activity and oxygen uptake in Balanus balanoides

1965 ◽  
Vol 45 (2) ◽  
pp. 387-403 ◽  
Author(s):  
R. C. Newell ◽  
H. R. Northcroft
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Mantle Cavity ◽  
The Body ◽  
Effect Of Temperature ◽  
Zero Rate ◽  
Rate Of Oxygen Consumption ◽  
The Relationship ◽  
Balanus Balanoides

The rate of cirral beat of Balanus balanoides is related to the logarithm of the body weight as an exponential function. In any one animal, there is little effect of temperature on cirral activity between 7·5° and 10° C. Between 10° and 20° C, however, there is a rapid increase in cirral beat with temperature followed by a fall at temperatures above 20° C.Balanus balanoides exhibits a fast, medium and zero rate of oxygen consumption. These rates of oxygen consumption correspond with (a) normal cirral beating, (b) ‘testing’ activity with no cirral movement, and (c) with the closure of the mantle cavity. Both of the possible levels of oxygen uptake are related to the logarithm of the body weight in a logarithmic fashion over the temperature range 7·5°–22·5° C. Temperature affects the two rates of oxygen consumption differently. In the slower rate (rate B) there is an increase in the rate of oxygen consumption between 7·5° and 14° C but there is no significant increase in the rate of oxygen consumption between 14° and 22·5 C°.

scholarly journals The Blood-system in the Serpulimorpha (Annelida, Polychaeta)

1950 ◽  
Vol s3-91 (16) ◽  
pp. 369-378
Author(s):  
JEAN HANSON
Keyword(s):  
Blood Supply ◽  
Peripheral Blood ◽  
Body Wall ◽  
Blood System ◽  
The Body ◽  
Dorsal Vessel ◽  
The Family ◽  
Body Wall Musculature

1. The blood-system in sabellids of the following genera is described: Sabella, Potamilla, Branchiomma, Dasychone, Amphiglena, Fabricia, Jasmineira, Dialychone, and Myxicola. 2. The central blood-system of Sabella is typical of the family, but the peripheral blood-system is variable. 3. The dorsal vessel lacks the valve and muscular sphincter found in some serpulids. 4. Lateral vessels are present only in Sabella and Dasychone. 5. The differences and similarities between sabellid and serpulid blood-systems are discussed. Special attention is given to the functions of sub-epidermal and coelomic capillaries and the blood-supply of the body-wall musculature.

Hibernation in the Eastern Pygmy Possum, Cercartetus-Nanus (Marsupialia, Burramyidae)

1993 ◽  
Vol 41 (1) ◽  
pp. 67 ◽  
Author(s):  
F Geiser
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Air Temperature ◽  
The Body ◽  
Daily Torpor ◽  
Rate Of Oxygen Consumption ◽  
The Mean ◽  
Cercartetus Nanus ◽  
Torpor Bouts

The pattern of torpor was examined in the eastern pygmy possum, Cercartetus nanus (21 g). Animals displayed torpor regularly in the laboratory, and the occurrence of torpor increased with decreasing air temperature (T(a)). At high T(a) (18-degrees-C) animals usually exhibited daily torpor, but torpor bouts of up to 2 days were observed occasionally. The duration of torpor bouts lengthened with a lowering of T(a) and the mean bout duration at T(a) = 5-degrees-C was 17.0 +/- 2.5 days. The minimum metabolic rate (measured as rate of oxygen consumption) of torpid individuals was 0.018 +/- 0.003 mL O2 g-1 h-1, which is less than 2% of the basal metabolic rate. The body temperature (T(b)) Of torpid animals fell to a minimum of 1.3 +/- 0.4-degrees-C. These results clearly demonstrate that Cercartetus nanus is a deep hibernator.

Heart rate as an indicator of oxygen consumption: influence of body condition in the king penguin

2001 ◽  
Vol 204 (12) ◽  
pp. 2133-2144 ◽  
Author(s):  
G. Froget ◽  
P. J. Butler ◽  
Y. Handrich ◽  
A. J. Woakes
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Body Condition ◽  
Active Oxygen ◽  
The Body ◽  
Regression Equations ◽  
Oxygen Pulse ◽  
Rate Of Oxygen Consumption ◽  
The Impact ◽  
The Relationship

SUMMARY The use of heart rate to estimate field metabolic rate has become a more widely used technique. However, this method also has some limitations, among which is the possible impact that several variables such as sex, body condition (i.e. body fat stores) and/or inactivity might have on the relationship between heart rate and rate of oxygen consumption. In the present study, we investigate the extent to which body condition can affect the use of heart rate as an indicator of the rate of oxygen consumption. Twenty-two breeding king penguins (Aptenodytes patagonicus) were exercised on a variable-speed treadmill. These birds were allocated to four groups according to their sex and whether or not they had been fasting. Linear regression equations were used to describe the relationship between heart rate and the rate of oxygen consumption for each group. There were significant differences between the regression equations for the four groups. Good relationships were obtained between resting and active oxygen pulses and an index of the body condition of the birds. Validation experiments on six courting king penguins showed that the use of a combination of resting oxygen pulse and active oxygen pulse gave the best estimate of the rate of oxygen consumption V̇O2. The mean percentage error between predicted and measured V̇O2 was only +0.81% for the six birds. We conclude that heart rate can be used to estimate rate of oxygen consumption in free-ranging king penguins even over a small time scale (30min). However, (i) the type of activity of the bird must be known and (ii) the body condition of the bird must be accurately determined. More investigations on the impact of fasting and/or inactivity on this relationship are required to refine these estimates further.

The Swimming Energetics of Trout

1971 ◽  
Vol 55 (2) ◽  
pp. 521-540 ◽  
Author(s):  
P. W. WEBB
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Swimming Performance ◽  
The Body ◽  
Control Group ◽  
Muscle System ◽  
Rate Of Oxygen Consumption ◽  
Wet Weight ◽  
Standard Rate ◽  
The Difference

1. The oxygen consumption of rainbow trout was measured at a variety of subfatigue swimming speeds, at a temperature of 15 %C. Five groups of fish were used, a control group and four groups with extra drag loads attached to the body. 2. The logarithm of oxygen consumption was linearly related to swimming speed in all five groups, the slope of the relationship increasing with the size of the extra drag load. The mean standard rate of oxygen consumption was 72.5 mg O2/kg wet weight/h. The active rate of oxygen consumption was highest for the control group (628 mg O2/kg/h) and fell with increasing size of the attached drag load. The active rate for the control group was high in comparison with other salmonid fish, and in comparison with the value expected for the fish. This was not a result of the extra drag loads in the other groups. No explanation for this high value can be found. 3. The critical swimming speed for a 60 min test period was 58.1 cm/sec (2.0 body lengths/sec) for the control group. The values for the critical swimming speeds were slightly higher than those measured for the same species in a previous paper (Webb, 1971). The difference between the two sets of critical swimming speeds is attributed to seasonal changes in swimming performance. 4. The aerobic efficiency was found to reach values of 14.5-15.5% based on the energy released by aerobic metabolism in comparison with the calculated required thrust. 5. The anaerobic contribution to the total energy budget in increasing-velocity tests is considered to be small, and can be neglected. 6. It is concluded that the efficiency of the muscle system in cruising will be approximately 17-20% over the upper 80% of the cruising-speed range, while the caudal propeller efficiency will increase from about 15-75 % over the same range. 7. Consideration of the efficiency values for the caudal propeller calculated here, and those predicted by Lighthill's (1969) model of fish propulsion, suggest that the efficiency of the propeller system will reach an optimum value at the maximum cruising speeds of most fish, and will remain close to this value at spring speeds.

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