Reduced red cell 2,3-diphosphoglycerate and adenosine triphosphate, hypophosphatemia, and increased hemoglobin-oxygen affinity after cardiac surgery

Serum inorganic phosphorous was decreased significantly on the third postoperative day following cardiac surgery in 18 patients initially studied. Reduced plasma inorganic phosphate has been shown to cause a reduced concentration of red cell organic phosphates, an important determinant of hemoglobin-oxygen affinity. Therefore, 10 consecutive patients were studied to determine if reduced 2,3-diphosphoglycerate (DPG) and adenosine triphosphate (ATP) concentration and increased hemoglobin-oxygen affinity accompanied the fall in serum inorganic phosphate concentration.

A significant fall in 2,3-DPG and an increase in hemoglobin-oxygen affinity was present in red cells of patients studied on the first postoperative day. A reduction in red cell ATP was also present and persisted for 5 days during which time red cell 2,3-DPG returned to levels which were in excess of preoperative values. The reduction in serum inorganic phosphorous followed the reduction in red cell 2,3-DPG and correlated with the reduction in ATP. The latter changes may indicate the diversion of glucose and more specifically 1,3-DPG into the Rapoport-Leubering pathway away from ATP generation at the phosphoglycerate kinase step and the utilization of plasma inorganic phosphate for 2,3-DPG resynthesis. Neither the transfusion of stored blood nor the effect of cardiopulmonary bypass fully explained the reduction in red cell 2,3-DPG and the inefficiency of hemoglobin function postoperatively. Further studies in postsurgical patients are needed to clarify the cause of the changes observed since they are potentially deleterious, especially in the subject with compromised cardiovascular and pulmonary function.

Effect of ethionine on carbohydrate and lipid metabolism

In ethionine-treated rats, the ATP content of adipose tissue was not decreased whereas in liver it was drastically reduced to about one-fifth of the control level. Shortly after the injection of ethionine, hepatic glycogen was depleted and the blood glucose concentration fell from 120 to 80 mg/100 ml. This was followed by a two- to threefold elevation of the plasma fatty acid level. Hepatic glucose-6-phosphate was decreased and was not elevated by administration of 2 mmoles of glucose unless ATP was partially restored to normal levels. When hepatic ATP was decreased, the disappearance of [(14)C]glucose from the blood and its incorporation into glycogen and glyceride-glycerol and the incorporation of [3-(14)C]pyruvate into glyceride-glycerol were reduced. 6 hr after ethionine injection the plasma triglyceride level fell but there was no significant change in the liver triglyceride concentration, but by 24 hr it had increased markedly. Lipogenesis in adipose tissue was depressed in vivo, possibly due to decreased glycerol-3-phosphate concentrations. A marked decrease of glycerol-3-phosphate in both liver and adipose tissue was noted. Administration of glucose effectively depressed plasma free fatty acid concentration and elevated the glycerol-3-phosphate levels. Ethionine injection to fasted animals further depressed the blood glucose and elevated the plasma free fatty acid level.

Bohr effect, 2,3-DPG and ATP concentrations in the blood of premature infants with RDS

In children with RDS, the concomitant respiratory-metabolic acidosis leads with the Bohr effect to a lowering of oxygen affinity (increases of P₅₀).However, pH reduction and resultant lowering of 2,3-DPG concentration in the erythrocytes make one expect an oxygen affinity increase. The question is thus to what extent the two influences overlap and neutralize each other. We wanted to take a look at this problem as part of a more extensive study, and so we measured the acid-base status, the oxygen affinity of hemoglobin, the 2,3-DPG, ATP, ADP and AMP contents in the blood of premature infants with RDS and in some term infants with RDS; then we compared these measurements with those of premature infants without RDS.