The uptake of 5-hydroxytryptamine, histamine, and their amino acid precursors by neoplastic mast cells.

Neoplastic mast cells of the mouse not only synthesize histamine and 5-hydroxytryptamine (5-HT)" ' but can take up biogenic amines, 4 a property also demonstrated by normal cells."'6 Previous experiments showed that uptake of 5-HT and histamine,3 but not of the precursor amino acids,2 was inhibited by imipramine, and, moreover, that this drug was more effective in inhibiting uptake of 5-HT than of histamine.' a-Methyldihydroxyphenylalanine inhibited uptake of 5-hydroxytryptophane (5-HTP) but not of histidine2 or of either amine.3 It seemed appropriate to study the effects of other subtances on the uptake of these amines and amino acids in order to see how useful these cells may be for the study of transport. At the same time, it was hoped to gain some insight to factors influencing uptake. Similar studies on amines have been described recently by Day and Stockbridge.'