. 2017 Dec 11;59(2):357–367. doi: 10.1194/jlr.M081380

TABLE 2.

Kinetic parameters for all n-3 and n-6 PUFA whole-body synthesis-secretion following infusion of ²H₅-ALA, ¹³C₂₂-DHA, ¹³C₁₈-LNA, and ¹³C₂₂-DPAn-6 over 3 h

Tracer Source	Fatty Acid	Maximal Rate of Synthesis (S_max, nmol/min)	Synthesis-Secretion Coefficient (k_1,PUFA, ml/min)	Daily Synthesis-Secretion Rate (nmol/day)	Turnover (F_PUFA, %/day)	Half-Life (t_1/2,PUFA,days)
n-3 PUFA pathway
ALA	ALA	0.24 ± 0.04^a	0.37 ± 0.05^a	1971 ± 393^a	12.8 ± 2.1^ab	0.068 ± 0.013^ab
	SDA	0.003 ± 0.001^de	0.004 ± 0.001^de	21.8 ± 4.3^de	8.4 ± 2.5^ab	0.16 ± 0.05^ab
	20:3n-3	0.012 ± 0.004^cd	0.019 ± 0.007^cd	92.8 ± 24.3^bcd	8.7 ± 2.8^ab	0.19 ± 0.07^ab
	20:4n-3	0.021 ± 0.007^bc	0.035 ± 0.012^bc	203 ± 75^bc	37.3 ± 12.8^a	0.035 ± 0.009^a
	EPA	0.040 ± 0.007^b	0.068 ± 0.013^b	369 ± 86^b	3.9 ± 0.9^b	0.38 ± 0.15^b
	DPAn-3	0.043 ± 0.009^b	0.072 ± 0.017^b	408 ± 116^b	4.0 ± 1.1^b	0.89 ± 0.67^b
	TPAn-3	0.001 ± 0.0001^e	0.001 ± 0.0001^e	7.6 ± 1.4^e	5.1 ± 1.1^b	0.34 ± 0.20^b
	THA	0.004 ± 0.001^d	0.007 ± 0.002^de	42.1 ± 12.9^cde	3.8 ± 1.0^b	0.78 ± 0.50^b
	DHA	0.011 ± 0.003^cd	0.017 ± 0.005^cd	94 ± 31.4^bcd	0.067 ± 0.023^c	30.4 ± 11.6^c
DHA	EPA	0.006 ± 0.001^#^#	0.13 ± 0.03^#^#	373 ± 121	4.3 ± 1.6	0.31 ± 0.07
	DHA	0.18 ± 0.03^#^#	4.2 ± 0.9^#^#	11780 ± 3147^#^#	8.9 ± 2.4^#^#	0.14 ± 0.04^#^#
n-6 PUFA pathway
LNA	LNA	0.427 ± 0.044^a,*	0.137 ± 0.018^a,*	28695 ± 4715^a,*	2.6 ± 0.4^a,*	0.31 ± 0.04^a,*
	GLA	0.005 ± 0.001^bc,*	0.002 ± 0.0003^bc,*	343 ± 72^bc,*	2.7 ± 1.0^ab,*	0.92 ± 0.59^ab,*
	20:2n-6	0.0014 ± 0.0003^cd,*	0.0005 ± 0.0001^cd,*	98 ± 25^cd	0.67 ± 0.22^b,*	2.8 ± 1.1^b,*
	DGLA	0.009 ± 0.003^bc,*	0.003 ± 0.001^bc,*	446 ± 130^bc	1.7 ± 0.4^ab,*	0.73 ± 0.23^ab,*
	ARA	0.011 ± 0.005^b,*	0.003 ± 0.001^b,*	610 ± 205^b	0.056 ± 0.018^c,*	23 ± 7^c,*
	22:4n-6	0.017 ± 0.01^b,*	0.005 ± 0.003^b,*	833 ± 494^b	2.0 ± 1.1^ab	1.2 ± 0.5^ab
	TTA	n.d.	n.d.	n.d.	n.d.	n.d.
	TPAn-6	n.d.	n.d.	n.d.	n.d.	n.d.
	DPAn-6^&^&	0.0004 ± 0.0001^d,*	0.0001 ± 0.00005^d,*	29 ± 11^d,*	0.067 ± 0.021^c	14.3 ± 6.5^c
DPAn-6	ARA	n.d.	n.d.	n.d.	n.d.	n.d.
	DPAn-6	0.013 ± 0.007^#,*	1.6 ± 0.6^#,*	1690 ± 609^#,*	6.2 ± 2.6^#^#	0.31 ± 0.10^#^#

Different superscript letters represent statistically different kinetic values between fatty acids and within a kinetic measure for each individual n-3 and n-6 PUFA biosynthetic pathway. Values are expressed as mean ± SEM, n = 8. DGLA, dihomo-γ-linolenic acid.

Represents significantly different kinetic values for an individual PUFA derived from DHA versus ALA, and DPAn-6 versus LNA precursors, P < 0.05.

*Represents significantly different kinetic values compared with n-3 PUFA biosynthetic pathway homologs for all n-6 PUFAs by t-test, P < 0.05.

^amp

n = 3 for DPAn-6 kinetic parameters from LNA.