On the normal activites of glucose-6-phosphate dehydrogenase and 6-phospho-gluconate dehydrogenase in bovine erythrocytes.

The activities of glucose-6-phosphate dehydrogenase and of 6-phos-pho-gluconate dehydrogenase have been determined in cows, heifers, bulls and calves. The material consisted of 80 RDM, 46 SDM, 31 Jersey animals older than 3 months, 16 newborn RDM calves and 29 fetuses of various breeds. a. In RDM averages of 322 ± 56 units G6PD and 52.8 ± 12.2 units 6PGD per 100 ml PGV were found. In SDM 330 ± 43 units G6PD and 47.1 ± 9.2 units 6PGD were found, and in Jersey 315 ± 39 units G6PD and 49.2 ± 8.0 units 6PGD per 100 ml PGV. The activities of both dehydrogenases were shown to be normally distributed in all three breeds. b. The 6PGD activities in SDM were significantly lower than in RDM, but no other breed differences between the mean activities were detected. c. There is no relation between the age (apart from fetuses and newborn calves), and milk yield of the animals and the activities of G6PD and 6PGD in the erythrocytes. d. Statistical treatment of the results demonstrates that there is no relation between the G6PD and 6PGD activities in the blood samples, and that the enzyme activities in units per 100 ml PGV is not correlated with MCHG. e. Further, the statistical treatment shows that when measuring G6PD and 6PGD activities in erythrocytes, PGV is to be preferred to hemoglobin concentration as parameter. f. In bovine fetuses G6DP activities more than twice as high as in adult erythrocytes were found, while the 6PGD activities were only slightly higher than in adult erythrocytes. After birth the high G6PD activities decreased over a period of 40 days to the normal level for mature cattle. The 6PGD activity also attains the normal level for older animals in approximately 40 days after birth.