Interrelationships between red cell nucleoside triphosphate content, and blood pH, O2-tension and haemoglobin concentration in the carp, Cyprinus carpio.

As a starting point for investigations of possible control factors for the nucleoside triphosphate content in carp red cells, we utilized the natural variability in blood physico-chemical parameters to test for interrelationships. By application of two-variable regression analysis, the red cell NTP content was found to be significantly correlated with arterial PO 2 and pH as well as with the blood haemoglobin (Hb) concentration. These correlations show a rise in red cell NTP content with falling pH as well as with falling Hb concentration, whereas a decrease in PO 2 was associated with a decrease in the content of NTP, particularly at low PO 2 values. Evaluation based on multiple regression analysis suggested that only PO 2 and pH significantly affected the red cell NTP content, and that the influence of changes in Hb concentration could be accounted for by naturally occurring simultaneous changes in PO 2 and pH. The multifactorial control of red cell nucleoside triphosphates is discussed in relation to the role of still unknown factors.