We previously reported that a single exercise session protects against fatty 
acid (FA)-induced insulin resistance, perhaps in part through augmented 
intramyocellular triacylglycerol (IMTG) synthesis. The aim of this study was to 
examine the effect of elevated FA availability after exercise on factors 
regulating IMTG metabolism. After exercise (90 minutes, 65% peak oxygen uptake), 
7 healthy women (body mass index, 23 ± 1 kg/m(2)) were infused overnight (16 
hours) with either a lipid and heparin solution (LIPID, 0.11 g fat per kilogram 
per hour) or saline (SALINE). We measured resting FA oxidation (indirect 
calorimetry) and obtained a skeletal muscle biopsy sample the next morning. The 
4-fold increase in overnight plasma FA concentration during LIPID increased IMTG 
by approximately 30% during LIPID vs SALINE. This was accompanied by an 
approximately 25% greater membrane-associated abundance of the FA transporter 
FAT/CD36 (P < .01) and an approximately 8% increase in the activity of the IMTG 
synthesis enzyme glycerol-3-phosphate acyltransferase (GPAT, P < .01). In 
contrast, resting FA oxidation was not affected. We also found no difference in 
the protein abundance of GPAT1 and diacylglycerol acyltransferase-1, 
diacylglycerol acyltransferase activity, or the abundance of the lipid droplet 
coat proteins (perilipins 2, 3, 4, and 5) between treatments. Our findings 
suggest that augmented capacity for FA flux into muscle (ie, via 
membrane-associated FAT/CD36), perhaps together with a slight yet significant 
increase in activity of a key IMTG synthesis enzyme (GPAT), may enhance IMTG 
storage when FA availability is high after exercise. The importance of the 
absence of a change in perilipin protein abundance despite increased muscle 
lipid storage remains to be determined.