Acid-base balance of hemolymph in Pacific oyster Crassostrea gigas in normoxic conditions
2018
Handa, T. (National Fisheries University, Shimonoseki City, Yamaguchi Pref. (Japan). Department of Applied Aquabiology) | Araki, A. | Kawana, K. | Yamamoto, K.
We examined hemolymph O2 partial pressure (Po2), pH, total CO2 content (Tco2), CO2 partial pressure (Pco2), and bicarbonate concentration ([HCO3sup(-)]) in order to evaluate the ability of the acid-base balance of the Pacific oyster Crassostrea gigas in normoxic conditions. Hemolymph was collected anaerobically through a cannula inserted into the adductor muscle of Pacific oyster submerged in experimental seawater. The mean values of hemolymph Po2, pH, and Tco2 were 62.0 torr, 7.414, and 1.87 mM/l, respectively. The apparent dissociation constant of carbonic acid (pKapp) was estimated using the following equation: pKapp = 33.462 - 13.032 . pH + 2.065 . pHsup(2) - 0.1088 . pHsup(3). Using alpha co2 (40.51 micro M/l/torr) and pKapp determined in this study, the hemolymph Pco2 and [HCO3sup(-)] were calculated as 2.18 torr and 1.78 mM/l, respectively. The non-bicarbonate buffer value (beta sub(NB)) was 0.732 Slykes. These hemolymph properties were compared with those of other marine bivalves. The Pacific oyster should have an acid-base balance that is similar to Pectinidae and Pteriidae bivalves, but which is different from Mytilidae bivalves.
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