This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Scott, D. F. Articles by Morris, H. P. Search for Related Content PubMed PubMed Citation Articles by Scott, D. F. Articles by Morris, H. P.

Naturally Occurring and Induced Levels of Amino Acid Transport and Tyrosine Aminotransferase in Rats Bearing Morris Hepatomas¹

McArdle Laboratory for Cancer Research, Medical Center, University of Wisconsin, Madison, Wisconsin 53706 [D. F. S., F. R. B., V. R. P.], and Department of Biochemistry, Howard University, College of Medicine, Washington, D. C. 20001 [H. P. M.]

The induction of -aminoisobutyrate (AIB) transport and tyrosine aminotransferase was studied in hepatomas and host livers of rats bearing Morris hepatomas 5123C, 7793, 7794A, 7794B, 7800, 9098, 9109, 9121, 9618A, 9618B, and 66, with the use of the following agents: N⁶,O²'-dibutyryl cyclic adenosine 3',5'-monophosphate, epinephrine, glucagon, isoproterenol, and theophylline. Tyrosine aminotransferase and AIB transport in hepatomas and host livers responded to the inducing agents in varying degrees from widely different basal levels. Thus, a wide diversity in patterns of induction was observed, with no two hepatoma lines responding identically to all inducing agents.

The basal levels of enzymic and transport activities were postively correlated in both tissues. However, the correlation in the hepatomas was more pronounced than in the host livers. The activities of both parameters in hepatomas were more sensitive than those in host liver to the endocrine state of the animal. Bilateral adrenalectomy resulted in marked reductions in the basal activities of tyrosine aminotransferase and AIB transport in hepatomas 5123C, 7794B, and 9108, but not in the basal activities of host livers. Differences in levels of AIB uptake were also noted for hepatomas carried in both sexes.

Although the responses elicited by N⁶,O²'-dibutyryl cyclic adenosine 3',5'-monophosphate mimicked those elicited by the hormones, the data obtained suggest that N⁶,O²'-dibutyryl cyclic adenosine 3',5'-monophosphate is not an obligatory intermediate in the induction of either tyrosine aminotransferase or AIB transport.

¹ Financial support was provided in part by Departmental Grant CA-07175 and by Training Grant T01-CA-5002 from the National Cancer Institute.

² Recipient of USPHS Postdoctoral Fellowship 1-FO2-32836. Present address: Department of Cell and Molecular Biology, Medical College of Georgia, Augusta, Ga. 30902.

³ Recipient of USPHS Postdoctoral Fellowship 1-FO2-43880. Present address: Division of Biological and Medical Sciences, Brown University, Providence, R. I. 02912.

⁴ To whom requests for reprints should be sent.

⁵ Recipient of Project Grant CA 10729.

Received 2/28/72. Accepted 6/19/72.