title: Estimation of plasma histidine flux in cows.
abstract: A tracer method is described for estimating the plasma amino acid flux in animals during steady state, and its application is illustrated using lactating cows that were injected intravenously with 14C- or 3H-labeled histidine. The method involves an extension of the occupancy principle in which the fraction of tracer recovered in a metabolic sink, casein or hemoglobin, provides the basis for calculating the amino acid flux. The plasma histidine flux was 25 g/day based on recovery of isotope in hemoglobin.
mesh_terms: D000818:Animals; D002417:Cattle / Q000097:blood*; D004905:Erythrocyte Aging; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006639:Histidine / Q000097:blood*; D006706:Homeostasis; D008892:Milk / Q000032:analysis; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D006639:Histidine