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@article{
 title = {Modulation of the cost of pHi regulation during metabolic depression: a (31)P-NMR study in invertebrate (Sipunculus nudus) isolated muscle.},
 type = {article},
 year = {2000},
 identifiers = {[object Object]},
 keywords = {4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid,4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid:,Amiloride,Amiloride: analogs & derivatives,Amiloride: pharmacology,Animals,Carbon Dioxide,Hydrogen-Ion Concentration,Ion Transport,Ion Transport: drug effects,Magnetic Resonance Spectroscopy,Muscles,Muscles: drug effects,Muscles: metabolism,Nematoda,Nematoda: metabolism,Oxygen Consumption},
 pages = {2417-28},
 volume = {203},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/10903156},
 month = {8},
 id = {cf9e560c-4f7a-3452-983e-41beaa2bdb31},
 created = {2012-12-06T09:13:40.000Z},
 file_attached = {true},
 profile_id = {0b777e31-8c9d-39dd-97a3-3e054bd99cfe},
 group_id = {764582e8-5773-3a66-8d6b-9b40e4fb5a88},
 last_modified = {2017-03-14T17:27:14.020Z},
 read = {false},
 starred = {false},
 authored = {false},
 confirmed = {true},
 hidden = {false},
 citation_key = {Portner2000},
 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 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.},
 bibtype = {article},
 author = {Pörtner, H O and Bock, C and Reipschläger, a},
 journal = {The Journal of experimental biology},
 number = {Pt 16}
}