scholarly journals Recovery from Anaerobiosis in the Intertidal Worm Sipunculus Nudus: II. Gas Exchange and Changes in the Intra- and Extracellular Acid-Base Status

1986 ◽  
Vol 122 (1) ◽  
pp. 51-64
Author(s):  
H. O. PÖRTNER ◽  
S. VOGELER ◽  
M. K. GRIESHABER
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Time Course ◽  
The Body ◽  
Coelomic Fluid ◽  
Acid Base ◽  
Extracellular Acidosis ◽  
Sipunculus Nudus ◽  
Acid Base Status ◽  
Negative Base

Intra- and extracellular acid-base status and changes of coelomic PCOCO2 were investigated during recovery following 24 h of anaerobiosis in Sipunculus nudus L. Metabolism, gas exchange and acid-base status were compared in animals collected during March and October. Anaerobiosis led to an uncompensated metabolic acidosis, the degree of the acidosis depending on the metabolic rate of the animals. During initial recovery in March animals, the acidosis was transiently aggravated in the extracellular, but not in the intracellular, compartment, indicating an efficient regulation of intracellular pH as soon as oxygen was available in the coelomic fluid. The extracellular acidosis was predominantly of non-respiratory origin. The non-respiratory part of the acidosis is attributed to the repletion of the phospho-l-arginine pool. The proton yield calculated from phosphagen resynthesis was highly correlated in time and in quantity to the observed negative base excess in the extracellular compartment. In October animals, strombine accumulation may have contributed to the acidosis that develops during recovery. The amount of succinate, propionate, and acetate in the coelomic plasma had already decreased when the acidosis developed. This discrepancy supports the conclusion that protons move between the body compartments independent of the distribution of anionic metabolites. The respiratory part of the acidosis is attributed to the repayment of an oxygen debt. The increase of PCOCO2 is higher in October than in March animals, probably because of differences in metabolic rate The time course of acid-base disturbances and their compensation is discussed in relation to the time course of metabolic events during recovery and to the priorities of the different processes observed.

Acid-base status and spiracular control during discontinuous ventilation in grasshoppers

1995 ◽  
Vol 198 (8) ◽  
pp. 1755-1763 ◽  
Author(s):  
J Harrison ◽  
N Hadley ◽  
M Quinlan
Keyword(s):  
Gas Exchange ◽  
Respiratory Physiology ◽  
Acid Base ◽  
Threshold Levels ◽  
Lubber Grasshopper ◽  
Open Phase ◽  
Internal Co2 ◽  
Acid Base Status

Many insects ventilate discontinuously when quiescent, exhibiting prolonged periods during which little or no gas exchange occurs. We investigated the consequences of discontinuous ventilation (DV) on haemolymph acid­base status and tested whether spiracular opening during DV is due to changes in internal gas tensions in the western lubber grasshopper Taeniopoda eques. At 15 °C, resting T. eques exhibited interburst periods of about 40 min. During the interburst period, haemolymph PCO2 rose from 1.8 to 2.26 kPa, with minimal acidification of haemolymph. Animals in atmospheres in which PCO2 was 2 kPa or below continued to exhibit DV, while atmospheres in which PCO2 was 2.9 kPa or above caused cessation of DV. These data indicate that accumulation of internal CO2 to threshold levels between 2 and 2.9 kPa induces spiracular opening in grasshoppers. In contrast to the situation in lepidopteran pupae, variation in atmospheric PO2 had no effect on interburst duration. Relative to lepidopteran pupae, the internal PCO2 of grasshoppers during DV is threefold lower, the PCO2 required for triggering spiracular opening is also threefold lower, and the open phase spiracular conductance is at least tenfold higher, demonstrating that considerable diversity exists in these aspects of insect respiratory physiology.

scholarly journals Modulation of the cost of pHi regulation during metabolic depression: a (31)P-NMR study in invertebrate (Sipunculus nudus) isolated muscle

2000 ◽  
Vol 203 (16) ◽  
pp. 2417-2428 ◽  
Author(s):  
H.O. Portner ◽  
C. Bock ◽  
A. Reipschlager
Keyword(s):  
Steady State ◽  
Marine Invertebrate ◽  
Metabolic Depression ◽  
Acid Base ◽  
Extracellular Acidosis ◽  
Nmr Study ◽  
Sipunculus Nudus ◽  
Delayed Recovery ◽  
Dimethyl Amiloride

Extracellular acidosis has been demonstrated to play a key role in the process of metabolic depression under long-term environmental stress, exemplified in the marine invertebrate Sipunculus nudus. These findings led to the hypothesis that acid-base regulation is associated with a visible cost depending on the rate and mode of H(+)-equivalent ion exchange. To test this hypothesis, the effects of different ion-transport inhibitors on the rate of pH recovery during hypercapnia, on energy turnover and on steady-state acid-base variables were studied in isolated body wall musculature of the marine worm Sipunculus nudus under control conditions (pHe 7.90) and during steady-state extracellular acidosis (pHe 7.50 or 7.20) by in vivo (31)P-NMR and oxygen consumption analyses. During acute hypercapnia (2 % CO(2)), recovery of pHi was delayed at pHe 7.5 compared with pHe 7.9. Inhibition of the Na(+)/H(+)-exchanger by 5-(N,N-dimethyl)-amiloride (DMA) at pHe 7.5 delayed recovery even further. This effect was much smaller at pHe 7.9. Inhibition of anion exchange by the addition of the transport inhibitor 4, 4′-diisothiocyanatostilbene-2,2′-disulphonic acid (DIDS) prevented pH recovery at pHe 7.5 and delayed recovery at pHe 7.9, in accordance with an effect on Na(+)-dependent Cl(−)/HCO(3)(−) exchange. The effects of ouabain, DIDS and DMA on metabolic rate were reduced at low pHe, thereby supporting the conclusion that acidosis caused the ATP demand of Na(+)/K(+)-ATPase to fall. This reduction occurred via an inhibiting effect on both Na(+)/H(+)- and Na(+)-dependent Cl(−)/HCO(3)(−) (i.e. Na(+)/H(+)/Cl(−)/HCO(3)(−)) exchange in accordance with a reduction in the ATP demand for acid-base regulation during metabolic depression. Considering the ATP stoichiometries of the two exchangers, metabolic depression may be supported by the predominant use of Na(+)/H(+)/Cl(−)/HCO(3)(−) exchange under conditions of extracellular acidosis.

Exercise and forced submergence in the pond slider (Trachemys scripta) and softshell turtle (Apalone ferox): influence on bimodal gas exchange, diving behaviour and blood acid-base status

1999 ◽  
Vol 202 (3) ◽  
pp. 267-278 ◽  
Author(s):  
B. Bagatto ◽  
R.P. Henry
Keyword(s):  
Gas Exchange ◽  
Metabolic Stress ◽  
Respiratory Acidosis ◽  
Diving Behaviour ◽  
Trachemys Scripta ◽  
Acid Base ◽  
Aerial Respiration ◽  
Acid Base Status ◽  
Softshell Turtle ◽  
Apalone Ferox

The dynamics of bimodal respiration, diving behaviour and blood acid-base status in the softshell turtle Trachemys scripta and the pond slider Apalone ferox were investigated at rest and under conditions of stress induced by exercise and forced submergence. During periods of forced submergence, only A. ferox doubled its aquatic gas exchange rate. Both A. ferox and T. scripta increased their aerial gas exchange profoundly following exercise and forced submergence, a pattern indicative of increased anaerobic respiration. Emersion duration increased significantly in A. ferox following forced submergence, and mean apnoeic time decreased significantly in A. ferox following exercise, indicating that a larger proportion of time at the surface was spent ventilating. Also, A. ferox maintained a one-breath breathing bout regardless of treatment. Submergence produced a respiratory acidosis in the plasma of approximately 0.2 pH units in magnitude in T. scripta and a mixed respiratory/metabolic acidosis of 0.4 pH units in A. ferox. Exercise induced an acidosis of 0.2 pH units of primarily metabolic origin in both species. Intra-erythrocyte pH was also reduced in both species in response to submergence and exercise. Both intracellular and extracellular acidoses were more severe and longer lasting in A. ferox after each treatment. Plasma [HCO3-] decreased by 25 % in both species following exercise, but only in A. ferox following submergence. Plasma lactate concentrations increased by equal amounts in each species following exercise; however, they returned to resting concentrations sooner in T. scripta than in A. ferox. A. ferox had significantly higher lactate levels than T. scripta following forced submergence as well as a slower recovery time. A. ferox, which is normally a good bimodal gas exchanger at rest, utilizes aerial respiration to a greater extent when under respiratory and/or metabolic stress. T. scripta, although almost entirely dependent on aerial respiration, is physiologically better able to deal with the respiratory and metabolic stresses associated with both forced submergence and exercise.

Simultaneous double-isotope autoradiographic measurement of local cerebral glucose metabolic rate and acid-base status in rat brain

1987 ◽  
Vol 2 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Alan H. Lockwood ◽  
Kathryn E. Peek ◽  
Marc Berridge ◽  
Linda Bogue ◽  
Eddy Yap
Keyword(s):  
Metabolic Rate ◽  
Rat Brain ◽  
Acid Base ◽  
Glucose Metabolic Rate ◽  
Acid Base Status ◽  
Double Isotope

scholarly journals Anaerobic Metabolism and Changes in Acid—Base Status: Quantitative Interrelationships and PH Regulation in the Marine Worm Sipunculus Nudus

1987 ◽  
Vol 131 (1) ◽  
pp. 89-105
Author(s):  
HANS-OTTO PÖRTNER
Keyword(s):  
Anaerobic Metabolism ◽  
Ph Value ◽  
Ph Regulation ◽  
Proton Exchange ◽  
Acid Base ◽  
Base Parameters ◽  
Sipunculus Nudus ◽  
Theoretical Predictions ◽  
Acid Base Status ◽  
Proton Generation

The quantitative influence of anaerobic metabolism on acid—base status and on acid-base regulation is investigated in Sipunculus nudus L. Proton generation by metabolism is calculated from theoretical predictions. The quantitative comparison of metabolic protons with non-respiratory protons found in the acid—base status is performed assuming a simplified model of the total animal. Taking the protonequivalent ion exchange between animals and ambient water into account, changes in the anaerobic acid—base status can be explained exclusively by proton generation in metabolism. It is concluded that the classical concept of acid—base physiology is adequate and that the consideration of strong ions is not required for a quantitative treatment of the acid—base status. The hypothesis that a quantitative correlation exists between metabolic and acid—base events is tested by comparing changes in acid—base status and in metabolism in animals exhibiting different metabolic rates. For this purpose, a method is developed for the calculation of intracellular pH from metabolite concentrations and extracellular acid—base parameters. Proton exchange between intra-and extracellular compartments, which is found to depend upon the total amount of accumulated non-respiratory protons, demonstrates that pHi is regulated even during anaerobiosis. The defended pH, value, however, is lower during anaerobiosis than during subsequent recovery. Note: Address for reprint requests

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