Abstract #285

# 285
Pretreatment with saturated and unsaturated fatty acids regulates [1-14C] C16:0 metabolism in Madin-Darby bovine kidney cells.
Katherine E. Boesche*1, Stephanie L. Koser1, Shawn S. Donkin1, 1Purdue University, West Lafayette, IN.

Metabolic fates of fatty acids (FA) may be influenced by circulating FA concentration. Previous work in our lab demonstrated an ability of C18:3n-3 cis to ameliorate gene expression of pyruvate carboxylase (PC) after depression by either C16:0 or C18:0. PC catalyzes oxaloacetate (OAA) synthesis and ostensibly links gluconeogenesis and FA metabolism. Our objective was to determine effects of co-presence of saturated and unsaturated FA pretreatments on cellular partitioning of [1-14C] C16:0 metabolism to CO2 or acid-soluble products (ASP) in Madin-Darby bovine kidney (MDBK) cells. We hypothesized that the ratio of saturated to unsaturated FA pretreatments regulates [1-14C] C16:0 partitioning to CO2 or ASP. Cells at 80% confluence were exposed for 21h to either individual FA bound to BSA (C16:0, C18:0, C18:1n-9 cis or C18:3n-3 cis) or FA cocktails in 10:90, 25:75, 50:50, 75:25 or 90:10 ratios for combinations of C16:0: C18:3n-3 cis or C18:0: C18:3n-3 cis or C18:1n-9 cis: C18:3n-3 cis. Total pretreatment FA concentration was 1.0 mM and was applied in triplicate to 3 cell replicates. Following pretreatment, cells were incubated in the presence of 1.0 mM [1-14C] C16:0 for 3h before CO2 and ASP collection. Data were analyzed using PROC MIXED of SAS. The model accounted for fixed effects of pretreatment and random effects of replicate. Pretreatments with either C16:0 or C18:0 alone significantly (P < 0.01) depressed subsequent oxidation of [1-14C] C16:0 to ASP by 62.7% and 41.2%, respectively, compared with C18:3n-3 cis pretreatments. Similar patterns were seen with [1-14C] C16:0 oxidation to CO2. ASP production from [1-14C] C16:0 positively correlated (r = 0.68, P < 0.01) with PC gene expression from previous experiments. CO2 production from [1-14C] C16:0 did not correlate (r = 0.30, P > 0.10) with PC expression. In conclusion, activation of PC gene expression by C18:3n-3 cis may play a critical role in setting the capacity for OAA synthesis and determining metabolic fates of FA. Results show a regulation of ketone production by MDBK cells in response to saturated and unsaturated FA pretreatments.

Key Words: fatty acid oxidation, ketogenesis, pyruvate carboxylase