The effect of hydrogen peroxide on isolated body wall of the lugworm Arenicola marina (L.) at different extracellular pH levels.
The effect of hydrogen peroxide on the rate of tissue oxygen consumption, on intracellular pH (pH(i)) and on malondialdehyde (MDA) accumulation was studied in isolated body wall tissue of the lugworm Arenicola marina (L.). H2O2 effects were investigated at various levels of pH(i) by changing medium pH (pH(e)). The largest decrease of tissue oxygen consumption (by 17% below controls), as well as the highest degree of MDA accumulation (four-fold compared to control values) after H2O2 exposure were found at acidic pH(e) of 6.4. This was attributed to the higher redox potential of H2O2 in acidic solutions. Oxygen consumption at alkaline pH(e) (8.5) was not affected by H2O2. MDA accumulation in the tissue was considerably lower than at pH(e) 7.4 or 6.4. Despite pH dependent alterations of H2O2 redox potential, we observed more or less constant pH(e) independent acidification of the tissue upon exposure to H2O2. We attributed the acidification to an inhibition of ATP consuming proton equivalent ion transport across the cellular membrane. Inactivation of carrier proteins is discussed to be responsible for the decrease in tissue oxygen consumption. However, with a larger effect on oxygen consumption at acidic pH(e) values, the latter may not be the only explanation, but additional impairment of other energy demanding processes may be involved.
Biologie I/Benthische Okosysteme, Alfred-Wegener-Institut für Polar-und Meeresforschung, Columbusstrasse, D-27568, Bremerhaven, Germany. dstorch@awi-bremerhaven.de
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D000136:Acid-Base Equilibrium / Q000187:drug effects; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects; D005110:Extracellular Space; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects*; D011077:Polychaeta; D017382:Reactive Oxygen Species / Q000378:metabolism
D008563:Membrane Lipids; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D006861:Hydrogen Peroxide