Inhibition of fatty acid incorporation into adipose tissue triglycerides in Ehrlich ascites tumor-bearing mice.

Using a recently developed technique of direct tracer injection into selective adipose tissue sites (Baker et al., Mech. Ageing Dev., 27: 295-313, 1984), we have studied the esterification of free fatty acids (FFA) to triglyceride fatty acids in the epididymal fat pads of normal and Ehrlich ascites carcinoma-bearing mice. We have tested the hypothesis that, during Ehrlich ascites carcinoma growth, a defect develops, resulting in the inhibition of the esterification and incorporation of FFA into adipose tissue diglyceride and triglyceride fatty acids. Our technique allowed the measurement of the disappearance of [1-14C]palmitic acid as FFA and its incorporation into di- and triglyceride fatty acids over 1 h. Multicompartmental analysis was used to compute the fractional rates of esterification and turnover. Using measured FFA pool sizes and assuming near-steady-state conditions, we estimated the transport rates (mass/time) of fatty acid esterification and turnover. Our results indicate that, compared to controls (normal mice), the epididymal fat pads of mice bearing early (5-day) and advanced (9-day) Ehrlich ascites carcinoma, respectively, show: 65% and near complete (congruent to 99%) decreases in the fractional rates of FFA esterification; about 2- and 24-fold increases in the FFA pool sizes; and 40% and 70% decreases in the transport rates of esterification.