ABSTRACT
Blood pH in the antarctic cod (Dissostichus mawsoni) and in two Trematomus species, occurring at –1·9°C, is extremely high ( ∼ 8·2 to 8·3). This supports and extends Rahn’s (1966) model for the temperature-pH relationship in cold-blooded vertebrates.
The blood of D. mawsoni shows a low oxygen affinity (P50 ≃ 14·5 mmHg at pH 8·16 and – 1·9°C). Despite normal in vitro temperature and pH sensitivities, blood P50 increases only slightly when five fish are temperature-stressed ( + 4 ·0 °C), or become acidotic as a result of agitational stress (blood pH 7 ·71 ), primarily as a result of compensatory decreases in blood ATP levels.
Oxygen-binding properties of ‘stripped’ (cofactor-firee) solutions of D. maw-soni haemoglobin were measured in attempts to elucidate the molecular mechanisms involved in the function of the pigment.
