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Titolo:
ACID-BASE REGULATION, METABOLISM AND ENERGETICS IN SIPUNCULUS-NUDUS AS A FUNCTION OF AMBIENT CARBON-DIOXIDE LEVEL
Autore:
PORTNER HO; REIPSCHLAGER A; HEISLER N;
Indirizzi:
ALFRED WEGENER INST POLAR & MARINE RES D-27515 BREMERHAVEN GERMANY HUMBOLDT UNIV BERLIN,LEHRSTUHL TIERPHYSIOL D-10115 BERLIN GERMANY MAX PLANCK INST EXPT MED D-3400 GOTTINGEN GERMANY
Titolo Testata:
Journal of Experimental Biology
fascicolo: 1, volume: 201, anno: 1998,
pagine: 43 - 55
SICI:
0022-0949(1998)201:1<43:ARMAEI>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
LAND SNAIL OREOHELIX; INTRACELLULAR PH; ENVIRONMENTAL HYPERCAPNIA; NITRILOTRIACETIC ACID; ENERGY-METABOLISM; PROTEIN-SYNTHESIS; MYTILUS-EDULIS; DORMANCY; INVERTEBRATES; OXYCONFORMER;
Keywords:
ACID-BASE REGULATION; AMMONIA EXCRETION; BUFFER VALUE; CO2 PARTIAL PRESSURE; ENVIRONMENTAL HYPERCAPNIA; EXTRACELLULAR PH; FREE ADP; GIBBS FREE ENERGY CHANGE OF ATP HYDROLYSIS; H+ TRANSFER; INTRACELLULAR PH; METABOLIC DEPRESSION; NITROGEN METABOLISM; PHOSPHO-L-ARGININE; VENTILATION; PEANUT WORM; SIPUNCULUS NUDUS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
46
Recensione:
Indirizzi per estratti:
Citazione:
H.O. Portner et al., "ACID-BASE REGULATION, METABOLISM AND ENERGETICS IN SIPUNCULUS-NUDUS AS A FUNCTION OF AMBIENT CARBON-DIOXIDE LEVEL", Journal of Experimental Biology, 201(1), 1998, pp. 43-55

Abstract

Changes in the rates of oxygen consumption and ammonium excretion, inintra-and extracellular acid-base status and in the rate of H+-equivalent ion transfer between animals and ambient water were measured during environmental hypercapnia in the peanut worm Sipunculus nudus. During exposure to 1% CO2 in air, intracellular and coelomic plasma P-CO2 values rose to levels above those expected from the increase in ambient CO2 tension. Simultaneously, coelomic plasma P-O2 was reduced below control values, The rise in P-CO2 also induced a fall in intra- and extracellular pH, but intracellular pH was rapidly and completely restored, This was achieved during the early period of hypercapnia at the expense of a non-respiratory increase in the extracellular acidosis, ThepH of the extracellular space was only partially compensated (by 37 %) during long-term hypercapnia, The net release of basic equivalents under control conditions turned to a net release of protons to the ambient water before a net, albeit reduced, rate of base release was re-established after a new steady state had been achieved with respect to acid-base parameters. Hypercapnia also affected the mode and rate of metabolism, It caused the rate of oxygen consumption to fall, whereas the rate of ammonium excretion remained constant or even increased, reflecting a reduction of the O/N ratio in both cases, The transient intracellular acidosis preceded a depletion of the phosphagen phospho-L-arginine, an accumulation of free ADP and a decrease in the level of Gibbs free energy change of ATP hydrolysis, before replenishment of phosphagen and restoration of pHi and energy status occurred in parallel. Inconclusion, long-term hypercapnia in vivo causes metabolic depression, a parallel shift in acid-base status and increased gas partial pressure gradients, which are related to a reduction in ventilatory activity, The steady-state rise in H+-equivalent ion transfer to the environment reflects an increased rate of production of protons by metabolism,This observation and the reduction of the O/N ratio suggest that a shift to protein/amino acid catabolism has taken place, Metabolic depression prevails, with completely compensated intracellular acidosis during longterm hypercapnia eliminating intracellular pH as a significant factor in the regulation of metabolic rate in vivo, Fluctuating levelsof the phosphagen, of free ADP and in the ATP free energy change values independent of pH are interpreted as being correlated with oscillating ATP turnover rates during early hypercapnia and as reflecting a tight coupling of ATP turnover and energy status via the level of free ADP.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 15:49:49