Elimination Kinetics of α-Amino-iso-butyric Acid in Non-Pregnant and Pregnant Rabbits

Abstract

CHANGES in the maternal metabolic and excretory functions occur during pregnancy; the plasma elimination rates of many compounds, such as folic acid^1,2, cortisol^3–5, nalidixic acid or gentamycin⁶, have been found to differ in non-pregnant and pregnant subjects. Also, the plasma steady state concentration of most of the free amino acids is already lowered early in pregnancy. Here I report on the elimination rate of the model α-amino-iso-butyric acid (AIB) in pregnant and non-pregnant rabbits. I chose this amino acid because it is not metabolized^7,8; it is transported and distributed throughout the body by the same mechanism as the naturally occurring free amino acids preferring the A-mediating system^9,10; it is slowly and almost exclusively excreted by the kidneys^7,8,11; and it is believed to accumulate in fast growing foetal tissue^12,13. Twenty-one experiments were performed using nine rabbits. Ten experiments were carried out in the non-pregnant and eleven in the pregnant animal. The pregnant rabbits were investigated in the first and third weeks of gestation.