REDUCED SUPPRESSION OF PLASMA SATURATED FATTY-ACID MOBILIZATION AND OXIDATION BY FEEDING IN LYMPHOMA-BEARING MICE

  • 15 April 1990
    • journal article
    • research article
    • Vol. 50  (8) , 2221-2227
Abstract
Lymphoma-bearing mice have a circulating lipid-mobilizing factor, but increased plasma free fatty acid (FFA) turnover has not been demonstrable in earlier studies using postabsorptive tumor-bearing mice. We hypothesized that FFA mobilization in lymphoma-bearing mice is only elevated in fed mice and may best be observed at night (dark, reversed light cycle). AKR mice with early and advanced tumors (106 SL-3 lymphoma cells, i.p.) and controls were fed ad libitum (reversed light cycle, dark) or fasted 4 h (daylight, regular cycle) given injections of [14C]bicarbonate or [1-14C]palmitate-mouse serum albumin, i.v., and plasma [14C]FFA disappearance and/or breath 14CO2 were monitored. Plasma FFA mobilization, estimated by multicompartmental analysis (SAAM) of the oxidation rate was lower in fasted mice with advanced tumors [tumor, 9.5 .+-. 6.0% (%SE); controls, 14 .+-. 4.4% .mu.g-atoms fatty acid-carbon/min/30 g body weight, n = 3 to 6 mice/time point/group]. Feeding reduced these rates 90% in control mice and 53% in mice with early tumors, but only 14% in mice with advanced tumors. Plasma FFA fractional catabolic rates were 2.5 times faster in fed mice with advanced tumors than in controls. Diminished suppression of fatty acid mobilization in fed tumor-bearing mice (at night) probably accounts partially for the body fat loss.