Temperature acclimation and oxygen binding properties of blood of the European eel, Anguilla anguilla.

Abstract 1. 1. Temperature acclimation of the European eel, Anguilla anguiila , resulted in red cell GTP/Hb molar ratios of 1.20, 1.77 and 0.80 at 2, 17 and 29°C, respectively. A small increase in blood oxygen capacity was present in 29°C acclimated eels. 2. 2. The CO 2 Bohr effect and the shape of the oxygen binding curve ( n -Hill) were invariant with both temperature and GTP/Hb. 3. 3. The significant differences in the GTP/Hb ratio corresponded with a strong enhancement of the temperature effect on blood oxygen affinity between 2 and 17°C and a similarly strong compensation between 17 and 29°C. Predicted in vivo P 50 values were 3.0, 13.8 and 17.6 mmHg at 2°C, 17 and 29°C, respectively. 4. 4. The Actaptational value of these findings are discussed in relation to standard metabolic rates at the various temperatures. A tentative hypothesis is proposed that the present study confirms and expands earlier work and supports the contention that adjustments in blood oxygen affinity of thermally acclimated teleosts serve to provide them with an unloading O 2 tension for diffusion closely matching the standard oxygen requirements at the various temperatures.