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Titolo:
Modulation of the cost of pHi regulation during metabolic depression: A P-31-NMR study in invertebrate (Sipunculus nudus) isolated muscle
Autore:
Portner, HO; Bock, C; Reipschlager, A;
Indirizzi:
Alfred Wegener Inst Polar & Meeresforsch, D-27515 Bremerhaven, Germany Alfred Wegener Inst Polar & Meeresforsch Bremerhaven Germany D-27515 any
Titolo Testata:
JOURNAL OF EXPERIMENTAL BIOLOGY
fascicolo: 16, volume: 203, anno: 2000,
pagine: 2417 - 2428
SICI:
0022-0949(200008)203:16<2417:MOTCOP>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
VASCULAR SMOOTH-MUSCLE; ACID-BASE STATUS; NA+-K+-ATPASE; INTRACELLULAR PH; NITRILOTRIACETIC ACID; EXTRACELLULAR-SODIUM; ANAEROBIC METABOLISM; MAGNETIC-RESONANCE; SURVIVAL STRATEGY; PROXIMAL TUBULES;
Keywords:
acidosis; ATP turnover; pHe; H+-ATPase; pHi; metabolic rate; Na+/H+ exchange; Na+/K+-ATPase; Na+-dependent Cl-/HCO3- exchange; P-31-NMR; transport energetics; Sipunculus nudus;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Portner, HO Alfred Wegener Inst Polar & Meeresforsch, Postfach 120161, D-27515 Bremerhaven, Germany Alfred Wegener Inst Polar & Meeresforsch Postfach120161 Bremerhaven Germany D-27515
Citazione:
H.O. Portner et al., "Modulation of the cost of pHi regulation during metabolic depression: A P-31-NMR study in invertebrate (Sipunculus nudus) isolated muscle", J EXP BIOL, 203(16), 2000, pp. 2417-2428

Abstract

Extracellular acidosis has been demonstrated to play a key role in the process of metabolic depression under longterm 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 P-31-NMR and oxygen consumption analyses. During acute hypercapnia (2% CO2), 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-/HCO3- 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-/HCO3- (i.e. Na+/H+/Cl-/HCO3-) 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-/HCO3- exchange under conditions of extracellular acidosis.

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Documento generato il 29/10/20 alle ore 21:09:30