Cation transport and energy metabolism in the nucleated erythrocyte of the dogfish shark, Squalus acanthias

Abstract

1. 1. Electrolyte distribution in the nucleated erythrocyte of the dogfish shark, Squalus acanthias, resembles that found in low Na +-high K + mammalian erythrocytes. 2. 2. Na + efflux (20°C) averaged 14·9 ± 2·7 m-equiv × kg RBC H 2O −1 × hr −1, being reduced significantly by monoiodoacetate (10 −2 M), N 2 exposure, and ouabain (10 −4 M). 3. 3. K + influx (20°C) averaged 9·1 ±4·0 m-equiv × kg RBC H 2O −1× hr −1, being reduced significantly by exposure to 12°C and ouabain (10 −4 M). 4. 4. Total O 2 consumption (30°C) averaged 3·14 ± 0·76 mM × kg RBC H 2O −1× hr −1. Sixty-five per cent of Q́O 2 is related to ATP generation. 5. 5. Lactate production (30°C) averaged 1·52 mM × kg RBC H 2O −1 × hr −1. Inhibition of oxidative phosphorylation produced a Pasteur effect. 6. 6. Total energy availability exceeds that required for cation transport, suggesting that other energy-consuming processes are present. A substantial amount of energy required for cation transport is presumably derived from oxidative phosphorylation.