Relationship between cellular ATP, potassium, sodium and magnesium concentrations in mammalian and avian erythrocytes

Intracellular K+/Na+ ratios of erythrocytes of various mammalian species are known to differ markedly. We have measured ATP, K+, Na+, Mg2+, H2O contents of erythrocytes of twelve mammalian and three avian species. Our results indicate that the intracellular ATP concentration in erythrocytes of different species is in close positive correlation with the K+/Na+ ratios (linear correlation coefficient, r = 0.852). Furthermore, ATP levels in erythrocytes of individual sheep with different potassium concentrations correspond with their K+/Na+ ratios (r = 0.747). Intracellular magnesium concentrations also correlate with ATP concentrations in erythrocytes of different species (r = 0.629) and in different sheep (r = 0.549).