TABLE 2.

Chain shortening and chain elongation

	Fraction of Palmitate from Chain Shortening of [U-13C]Stearate		Fraction of Stearate from Chain Elongation of [U-13C]Palmitate
Group	Average ± SD	P	Average ± SD	P
	m16palmitate/m18stearatea		m18+ m16stearate/m16palmitatea
A (control)	0.0263 ± 0.0013		0.548 ± 0.070
B	0.0423 ± 0.0008	<0.001	0.679 ± 0.054	0.031
C	0.0460 ± 0.0028	<0.001	0.705 ± 0.065	0.023
D	0.0539 ± 0.0006	<0.001	0.477 ± 0.147	0.248

Chain shortening is represented by the ratio m₁₆ palmitate/m₁₈ stearate. Chain elongation is represented by the ratio (m₁₈+m₁₆) stearate/m₁₆ palmitate. m₁₈ is made from M+16 palmitate and M+2 acetyl-CoA. The M+2 acetyl-CoA is derived from labeled palmitate oxidation and the exogenous [1,2-¹³C]acetate.

^aOne minus the fraction of shortening or elongation equals the fraction contributed by unlabeled (preexisting) stearate or palmitate plus the fraction from de novo synthesis (m₂, m₄, etc.).