Biochemical composition of edge and center of malignant hamster insulinoma

The purpose of this study was to determine if there is a difference in the biochemical composition of the edge of a tumor and the center of a tumor. There was a greater concentration of histamine in the edge (mean +/- SEM, 9.3 +/- 1.2 pmole/mg of wet weight) than in the center (3.6 +/- 0.4 pmole/mg of wet weight) of a transplantable golden hamster insulinoma. There was, however, no difference in the concentration of norepinephrine, protein, DNA, or phosphate, or in the activity of the enzymes, monoamine oxidase, catechol-O-methyltransferase, L-dopa decarboxylase, or 5'-nucleotidase in the edge or in the center of the tumor. Using chemical analysis and autoradiography, there was a comparable incorporation of tritiated thymidine in the edge and in the center of the tumor.