ABSTRACT
A typical whole blood Oz-equilibrium curve from Squalus acanthias had a P50 of 13·2 mmHg and was slightly sigmoidal, having an n value of 1·6 at 15°C, 
(pH = 7·85). A small Bohr effect was present (ϕ= −0·28) together with a weak Haldane effect and no Root shift.
The predominant trinucleotide, determined by thin layer chromatography, was ATP (0·44 ±0·13 S.D. mmol l−1 blood) with smaller amounts of GTP present (0·07 ± 0·02S.D. mmol 1−1). Total nucleotide concentrations, determined enzymatically, were low by comparison with teleosts. Incubation of erythrocytes with or without oxygen, or in the presence of a metabolite-enriched ‘cocktail’ showed limited potential for phosphate cofactor regulation of blood oxygen affinity.
