The Venous Plasma Free Amino Acid Levels During the First Hours of Life

Summary During the first hours of extrauterine life the venous plasma of the fasting normal newborn shows a fast decline of valine, leucine, isoleucine, lysine and alanine levels, while the glycine level and the ornithine/arginine quotient seem to increase. These changes are not caused by urinary excretion and are the same as those found in calorie undernutrition. The fasting newborn of mothers with hypertension of pregnancy, who are underweight and short for gestational age, have increased levels of valine, leucine and isoleucine during the first hours after birth and a tendency towards a more rapid decline of the levels thereafter. The alanine and proline levels seem to “resist” the general decline during the initial fast. These changes in the homeostasis of plasma free amino acids are not due to short gestational period. They are the same as those found in protein deficiency.