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Studies on Composition and Leakage of Proteins and Esterases of Normal Rat Liver and Morris Hepatoma 5123 t.c.¹

Departments of Biochemistry and Pharmacology, University of Toronto, Toronto, Canada, and the Laboratory of Biochemistry, National Cancer Institute, NIH, Bethesda, Maryland

The addition of 0.5% ethylenediaminetetraacetate (EDTA) to the incubation medium caused a significantly greater increase in protein leakage from normal Buffalo-strain rat liver slices (55%) than from slices of Morris 5123 t.c. hepatoma (33%) or of liver of tumor-bearing animals (25%). Electrophoresis in urea and non-urea starch gels revealed that the pattern of soluble proteins leaking from slices of the 5123 t.c. hepatoma was very similar to that of normal liver. The more basic soluble proteins, previously found to be markedly reduced in primary p-dimethylaminoazobenzene-induced hepatomata, were only moderately reduced in homogenates of the Morris hepatoma. Addition of EDTA to the incubation medium increased the leakage of a fraction designated "basic protein 4" from normal liver slices, but this effect was not demonstrable with the tumor slices.

The leakage of esterases into the incubation medium was also studied. All of the esterases present in homogenates of normal liver and the hepatoma were found to leak into the incubation medium. However, the tumor homogenates showed a marked reduction in a fast-migrating esterase (Zone 1). Electrophoresis of plasma proteins and esterases revealed frequently-occurring changes in samples from tumor-bearing animals, including an extension of the albumin front, a decrease in the fast ₁-globulin, a marked increase in albumin esterase activity and a decrease in cholinesterase.

The findings demonstrate a possible difference with respect to the influence of divalent cations on the permeability of the cell membranes of normal liver, host liver, and this hepatoma, as well as differences between their soluble protein and esterase profiles.

¹ Supported by grants from the Medical Research Council of Canada (R.K.M.) and the National Cancer Institute of Canada (H.K.). A preliminary report of this work was presented at the meeting of the Federation of American Societies of Experimental Biology, Chicago, Ill., in April 1964.

² Present address: McArdle Memorial Laboratory, Madison, Wisc.

Received 1/ 3/66. Accepted 9/28/66.