Simultaneous determination of endogenous and orally administered (15)N-labeled polyamines in rat organs.

A method for the simultaneous determination of polyamines (putrescine, spermidine, and spermine) by ionspray ionization-mass spectrometry was modified to determine (15)N-labeled polyamines together with unlabeled polyamines using (13)C,(15)N double-labeled polyamines as internal standards. This technique permitted the use of (15)N-labeled polyamines as tracer compounds to follow polyamine biosynthesis, interconversion, and absorption. The method was used to examine the organ distribution of orally administered (15)N-labeled polyamines in rats. Each (15)N-labeled polyamine was taken up by the three organs tested: the small intestine, liver, and kidney. The uptake of (15)N-labeled spermidine was greater than that of (15)N-labeled spermine and putrescine. Administration of a mixture of (15)N-labeled polyamines was useful for determining the disposition of each (15)N-polyamine absorbed from the intestinal tract.