We have tested the hypothesis proposed by Costa, Lyles, and Ullrich. (Effect of Human and Experimental
Cancer on the Conversion of 14C
Tripalmitin to 14CO2.
Cancer (Phila.), 38:1259-1265, 1976) that the transport and/or oxidation of
triglyceride fatty acids is markedly impaired in rodents bearing a growing s.c.
carcinoma. Specifically, we have tested whether oxidation of
triglyceride fatty acids is depressed in
cancer-bearing animals. Mice inoculated s.c. with Ehrlich
carcinoma cells were given
injections (i.v. and i.p.) of 14C-labeled
triglyceride fatty acids prepared as
very-low-density lipoproteins by physiological methods or (i.p.) with [-14C]
tripalmitin dissolved in
peanut oil during both early (3 to 4 days) and advanced (7 to 8 weeks) stages of
tumor growth. Specific activity of the expired 14CO2 was measured for periods ranging from 1 to 7 hr following
injections. Because
cancer-bearing mice can become severely hypertriglyceridemic, plasma
triglyceride pool sizes were also measured during each experiment to account for the effects of possible differential dilution of the tracers. At no instance did we find any significant differences between specific activities of expired 14CO2 or plasma
triglyceride pool sizes of the
cancer-bearing animals and controls. Thus, a
cancer-induced impairment of
triglyceride fatty acid transport and metabolism to CO2, such as reported by Costa et al., does not seem to be a universal phenomenon in rodents.