HUMAN FETAL GROWTH RETARDATION: II. ENERGY METABOLISM IN LEUKOCYTES

Abstract

This study was initiated to determine if there was a unique pattern for certain cell energy functions in leukocytes of mothers and their small for gestational age (IUM) infants at the time of birth. Further, the study attempted to determine if these patterns of cell energy functions were similar to those found in infants with severe postnatal protein-calorie malnutrition.

In leukocytes, the protein/DNA ratio (cell size) was larger in the IUM infants (cord blood) and their mothers than in those of the full-term (FT) and premature (AGA) groups. The contents of ATP, total adenine nucleotides, pyruvic kinase (PK), and adenylate kinase (AK) in leukocytes of IUM infants were significantly lower than those of the ACA and FT infants.

The energy charge of the adenylate system was calculated from the content of adenine nucleotides (ATP + ½ ADP) ÷ (ATP + ADP + AMP). There was no statistically significant difference between the groups.

A new parameter of cellular energy metabolism was suggested, based on the functional relationship between ATP and ADP which can be partially regulated by AK. Tentatively, this relationship is called the "energy capacity" and is quantified as (ATP + ½ ADP) x AK. The energy capacity in leukocytes of the IUM infants and their mothers was significantly lower than that of the FT and AGA infants and their mothers, respectively.

On the whole, the altered pattern of energy metabolism in leukocytes of the IUM infants was similar to that found in young infants with severe postnatal protein-calorie malnutrition, thus adding further support to the concept that fetal growth retardation is a manifestation of malnutrition in utero.

The similarity of enzyme pattern and adenine nucleotide contents between maternal and cord blood leukocytes at the time of delivery suggests some interrelation between energy metabolism in mothers and their fetuses.