Table 2.

Intramyocellular lipid changes and consequent impact on muscle glucose uptake or insulin resistance in studies where myotubes were cultured with different fatty acid mixtures.

Model	Fat Intervention/s	Muscle Lipid Change	Glucose Uptake/Insulin Resistance	Reference
L6 myotubes	PA, LA, DHA at 0.4 mmol/L	Muscle DAG:	Muscle glucose uptake:	[45]
			PA: ↓66%
		↑16-fold PA	PA + DHA: 20↑
		↓45% DHA	PA + LA: 55%↑
		↓65% LA	Myriocin: 2.0 to 2.5-fold↑
		Muscle Ceramide (in presence of PA):	Myriocin inhibits ceramide synthesis
		↑2.5-fold by DHA	DHA increases hydrolysis of sphingomyelin
		↑1.9-fold by LA
L6 myotubes	Palmitic acid (Palmitate), Linoleic acid (Linoleate)	Muscle DAG:	Muscle glucose uptake:	[53]
		↑5-fold PA
		No change by LA
	0.5 mmol/L	Muscle Ceramide:	↓by PA
		↑2-fold by PA	Unaffected by LA
		No change by LA
C12C12 myotubes	Normal FA mixture (40% SFA), high SFA FA mixture (60% SFA) & 100% Palmitic acid	Muscle DAG:	Akt phosphorylation impaired (p < 0.05) by 100% PA.	[54]
	Doses: 0.1, 0.2, 0.4 or 0.8 mmol/L	DAG accumulation unchanged with increasing dose of the two mixtures.	Modest impact of the two mixtures. No difference between 40% & 60% SFA.
		DAG accumulation increased with increasing dose of 100% PALM.
Vastus lateralis biopsies (Obese non-diabetic men & women)	Normal FA mixture (40% SFA), high SFA FA mixture (60% SFA) & 100% Palmitic acid	Muscle DAG:	Akt phosphorylation impaired (p > 0.05) by 100% PA.	[54]
	Dose: 0.4 mmol/L	100% PALM increased DAG over no FA control as well as the two FA mixtures.	Modest impact of the two mixtures. No difference between 40% & 60% SFA.

DAG, diacylglycerol; DHA, docosahexaenoic acid; FA, fatty acid; LA, linoleic acid; PA, palmitic acid; SFA, saturated fatty acid.