...—base variables and regulation. Accordingly, the sediment-dwelling worm Sipunculus nudus was used as an experimental model to investigate the correlation of acid—base-induced metabolic depression and protein/amino acid catabolism, by determining the rates of oxygen consumption, ammonia excretion and O/N...

...H. O. Pörtner; C. Bock; A. Reipschläger ABSTRACT 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...

... in the peanut worm Sipunculus nudus . During exposure to 1% CO 2 in air, intracellular and coelomic plasma values rose to levels above those expected from the increase in ambient CO 2 tension. Simultaneously, coelomic plasma was reduced below control values. The rise in also induced a fall in intra...

... 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), and [HCO 3 - ]. The acid–base status of the tissue was modified...

...I. Hardewig; A. D. F. Addink; M. K. Grieshaber; H. O. Pörtner; G. Van Den Thillart ABSTRACT Oxygen uptake and the mode of energy production in Sipunculus nudus L. were determined at different oxygen levels by means of direct and indirect calorimetry. Oxygen consumption declined linearly...

...H. O. Pörtner; N. A. Andersen; N. Heisler ABSTRACT Proton-equivalent ion transfer processes between animals and ambient water were determined under normoxic control conditions during anaerobiosis and the subsequent recovery period in the marine worm Sipunculus nudus L. During anaerobiosis...

...Hans-Otto Pörtner ABSTRACT 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...

...H. O. Pörtner; S. Vogeler; M. K. Grieshaber ABSTRACT Recovery from 24 h of anaerobiosis was investigated in Sipunculus nudus L. by monitoring changes in the concentrations of anaerobic metabolites in the musculature and in the coelomic plasma. The metabolic events in animals collected during March...

...H. O. Pörtner; S. Vogeler; M. K. Grieshaber ABSTRACT Intra- and extracellular acid-base status and changes of coelomic 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...