The distribution of label among the individual FAs of total
cellular lipids after 6 and 24 hours of incubation of fibroblasts from
patients with BCD or WD and age-matched control subjects with[
14C]18:2n-6 is shown in
Figure 3 . After 24 hours, approximately 50% of the radioactivity remained as
18:2n-6 in control, BCD, and WD samples, and only 18% of the label was
found in the higher PUFAs, mostly in 20:4n-6, but also to some degree
in 20:2n-6, 20:3n-6, 22:4n-6, and 22:5n-6. The conversion of 18:3n-3 to
its higher derivatives proceeded more rapidly
(Fig. 4) . At the end of 24 hours, 55% to 61% of the radioactivity
incorporated into cellular lipids remained as 18:3n-3, whereas
approximately 30% was incorporated in 20:3n-3, 20:4n-3, 20:5n-3,
22:5n-3, and 22:6n-3. There was no significant difference among
fibroblasts from normal control subjects and patients with WD or BCD in
18:2n-6 elongation and desaturation. However, incorporation of[
14C]18:3n-3 into all PUFAs was significantly
lower in fibroblasts from patients with BCD, with values ranging from
53% to 86% of that in control subjects. Samples from patients with WD
showed similar 18:3n-3 elongation and desaturation to those from
control subjects. Conversely, at 24 hours there was similar
incorporation of [
14C]18:2n-6 into 16:0, and
16:1n-7 FAs in BCD, WD, and control samples, whereas incorporation of[
14C]18:3n-3 into these pools increased to
levels roughly twice as high in BCD samples as those in control and WD
samples
(Figs. 3 4) .