Erythrocyte 2,3-diphosphoglycerate and erythropoietic activity in rabbits with severe bleeding anaemia superimposed in the early post-natal fall in haemoglobin.

Erythrocyte 2,3-diphosphoglycerate (2,3-DPG), whole blood haemoglobin (Hb), haematocrit (Hct), mean corpuscular haemoglobin concentration (MCHC) and reticulocyte percentage (Rt) were determined before and after bleeding in two groups of suckling chinchilla rabbits. One group was subjected to severe bleeding on the 12th, 15th, 18th and 21st day after birth and studied for 3 weeks, while the other was studied during the first 24 h after one severe bleeding on the 18th day. In the first group Hb and Hct fell to 2.7 g . dl-1 and 11.5%, respectively, on the 25th day. The fall was accompanied by a marked rise in Rt and decline in MCHC, reaching maximum and minimum on the 29th day, and a simultaneous, temporary decline in 2,3-DPG. In the other group the acute bleeding was accompanied by a marked fall in Hb and Hct, but no change in Rt and MCHC. 2,3-DPG was unchanged 8 h after the bleeding, but showed a rise during the following 16 h, definitely beyond the normal rise at this age. It is concluded that severe bleeding anaemia induces a rise in erythrocyte 2,3-DPG synthesis. However, the effect of the acute rise in 2,3-DPG is far from sufficient to maintain the O2 delivery capacity of the blood, and is completely offset by the influence of a subsequent change in the erythrocyte population towards younger cells with low 2,3-DPG.