Alanine kinetics in humans: influence of different isotopic tracers

Am J Physiol. 1984 Nov;247(5 Pt 1):E634-8. doi: 10.1152/ajpendo.1984.247.5.E634.

Abstract

Whole-body alanine kinetics were studied using continuous infusions of [15N]-, [3,3,3-2H3]-, [1-13C]-, and [3-13C]alanine tracers in healthy male subjects in the postabsorptive state. Alanine kinetics were highly dependent on the choice of isotopically labeled alanine. Highest rates of alanine flux (mean +/- SE) were obtained with the [3,3,3-2H3]alanine (474 +/- 41 mumol X kg-1 X h-1). [1-13C]- and [3-13C]alanine tracers gave intermediate values (297 +/- 12 and 317 +/- 22 mumol X kg-1 X h-1, respectively). The slowest rates of alanine turnover were measured with [15N]alanine (226 +/- 7 mumol X kg-1 X h-1). These results emphasize the heterogeneous metabolism of different portions of the alanine molecule and the importance of choosing an appropriate alanine tracer for studying different aspects of alanine metabolism.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Alanine / metabolism*
  • Body Height
  • Body Weight
  • Carbon Isotopes
  • Deuterium
  • Diet
  • Humans
  • Kinetics
  • Male
  • Nitrogen Isotopes

Substances

  • Carbon Isotopes
  • Nitrogen Isotopes
  • Deuterium
  • Alanine