Quantitative Determination of C 14 -Tyrosine Absorption in Melanated and Non-Melanated Mouse Tissues. ∗

Summary

Five microcuries of dl-tyrosine-2-C¹⁴ were administered to S91 melanoma-bearing mice (dba/1 strain) 7 days prior to time of sacrifice. Melanated and non-melanated tissues were quantitatively assayed for selective absorption of labelled tyrosine and/ or its derivatives. The order of uptake (/mg tissue carbon as measured manometrically) was highest in melanoma tissue and progressively lower in kidney, adrenal, liver, brain, thyroid, and skin and hair tissues. The combined technic of tissue combustion and precipitation of CO₂ as barium carbonate provides an extremely sensitive and reproducible activity measurement of labelled tyrosine uptake.