influence of experimental anaemia on blood acid-base regulation in vivo and in vitro in the starry flounder (Platichthys stellatus) and the rainbow trout (Salmo gairdneri)

Severe experimental anaemia caused a rise in and an associated fall in pH (respiratory acidosis) in arterial and venous blood of both flounder and trout in vivo. In some trout, but not in flounder, there was also a rise in blood lactate, indicating metabolic acidosis. In vitro, blood buffer capacities declined with haematocrit, a factor which contributed to the extent of the acidoses in vivo. However, haematocrit did not influence the pK1 of the plasma system or the actual measurement of blood pH. The Donnan ratio for varied linearly with pH over the range 7·0–7·6, indicating a passive distribution of across the trout erythrocyte. The present data, together with other recent results, indicate that the teleost red blood cell does play a role in plasma dehydration and CO2 excretion, and therefore opposes the theory of Haswell & Randall (1978) that the erythrocyte is functionally impermeable to .