Nonoxidative free fatty acid disposal is greater in young women than men.
BACKGROUND
Large increases in systemic free fatty acid (FFA) availability in the absence of a corresponding increase in fatty acid oxidation can create a host of metabolic abnormalities. These adverse responses are thought to be the result of fatty acids being shunted into hepatic very low-density lipoprotein-triglyceride production and/or intracellular lipid storage and signaling pathways because tissues are forced to increase nonoxidative FFA disposal.


OBJECTIVE
The objective of the study was to examine whether variations in postabsorptive nonoxidative FFA disposal within the usual range predict insulin resistance and hypertriglyceridemia.


METHODS
We measured: systemic FFA turnover using a continuous iv infusion of [9-10, (3)H]palmitate; substrate oxidation with indirect calorimetry combined with urinary nitrogen excretion; whole-body and peripheral insulin sensitivity with the labeled iv glucose tolerance test minimal model.


METHODS
the study was conducted at the Mayo Clinic General Clinical Research Center.


METHODS
Participants included healthy, postabsorptive, nonobese adults (21 women and 21 men).


METHODS
There were no interventions.


METHODS
Nonoxidative FFA disposal (micromoles per minute), defined as the FFA disappearance rate minus fatty acid oxidation.


RESULTS
Women had 64% greater nonoxidative FFA disposal rate than men but a better lipid profile and similar insulin sensitivity. There was no significant correlation between nonoxidative FFA disposal and whole-body sensitivity, peripheral insulin sensitivity, or fasting serum triglyceride concentrations in men or women.


CONCLUSIONS
Healthy nonobese women have greater rates of nonoxidative FFA disposal than men, but this does not appear to relate to adverse health consequences. Understanding the sex-specific interaction between adipose tissue lipolysis and peripheral FFA removal will help to discover new approaches to treat FFA-induced abnormalities.
Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA.
Christina
C
Koutsari
Rita
R
Basu
Robert A
RA
Rizza
K Sreekumaran
KS
Nair
Sundeep
S
Khosla
Michael D
MD
Jensen
D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D002153:Calorimetry, Indirect; D004032:Diet; D004734:Energy Metabolism / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000502:physiology; D007333:Insulin Resistance / Q000502:physiology; D007700:Kinetics; D050356:Lipid Metabolism / Q000502:physiology; D008297:Male; D010084:Oxidation-Reduction; D010168:Palmitates / Q000097:blood; D012727:Sex Characteristics; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010168:Palmitates; D014280:Triglycerides