Rats bearing intramuscular Walker tumor transplants, but exhibiting no evidence of circulatory insufficiency, were studied at weekly intervals, for 28 days. Hexobarbital anesthesia and zoxazolamine paralysis were prolonged in these animals, suggesting hepatic microsomal insufficiency. These changes were associated with progressive rough-surfaced endoplasmic reticulum (RER) dilatation, disorganization, disruption, and degranulation, as well as proliferation of the smooth-surfaced endoplasmic reticulum (SER). It remains to be established whether the livers of cancer patients also display similar abnormalities, yet such hepatic changes might be responsible for aberrations in hormone and drug metabolism.
HE EXACT CAUSE OF NONMETASTATIC MOR-
T phological abnormalities and biochemical aberrations in tumor-bearing patients and animals is not yet known. These alterations occur without any overt infection, hemorrhage, protein deficiency, or involvement of vital organs.
Enlargement and accelerated regeneration of liver in partially hepatectomized tumorbearing animals have attracted considerable attention.1.2JgJ!J Recent investigations indicate a relationship between carcinogenesis and hepatic miaosomal enzymes.SJ8 Therefore, it seemed worthwhile to study the sequence of changes in the liver ultrastructure of tumorbearing rats and to correlate these abnormalities with the in vivo metabolism of two micro-soma1 substrates-hexobarbital and zoxazolamine.