Blood and Liver Concentrations of Glutathione,and Plasma Concentrations of Sulfur-Containing Amino Acids in Chicks Fed Deficient,Adequate,or Excess Levels of Dietary Cysteine

Abstract

Abstract

Experiments were conducted with young male chicks to examine the influence of cysteine status on blood and liver glutathione (GSH) concentrations and plasma sulfur amino acids. The equivalence of cystine, cysteine, and GSH as sources of dietary cysteine for the chick was reconfirmed. Whole-blood GSH was unresponsive to dietary cysteine level, but liver GSH increased as dietary cysteine increased from a deficient level to the required level. Excess levels of cysteine (two or four times the chick's requirement) elicited no further increase in hepatic GSH. Plasma cystine concentration increased markedly (i.e., ninefold) and in a linear fashion while plasma cysteine increased only modestly (i.e., twofold) as dietary cysteine level increased.