Ramesha C S, Pickett W C
J Biol Chem. 1986 Nov 25;261(33):15519-23.
1-O-[3H]Alkyl-2-acetyl-sn-glycero-3-phosphocholine ([3H]PAF) and 1-O-[3H]alkyl-2-lyso-sn-glycero-3-phosphocholine ([3H]lyso-PAF) when incubated with rat polymorphonuclear leukocytes (PMN) were rapidly metabolized to 1-O-[3H]alkyl-2-acyl-sn-glycero-3-phosphocholine ([3H]alkyl-acyl-GPC) containing long chain acyl groups in the sn-2 position. The specificity and the absolute requirements of arachidonate (20:4) for acylation into PAF and lyso-PAF were investigated by comparing the rate of [3H]PAF and [3H]lyso-PAF metabolism by control rat PMN with that by rat PMN depleted of 20:4. Comparable rates of metabolism of [3H]PAF and [3H]lyso-PAF by both control and 20:4-depleted PMN were observed at all the concentrations of PAF and lyso-PAF studied. The nature of the fatty acyl group incorporated into the sn-2 position of the [3H]alkyl-acyl-GPC formed was analyzed by argentation chromatography. Dienoic fatty acids were the major fatty acid incorporated into the alkyl-acyl-GPC by both control and 20:4-depleted PMN at all the incubation times studied. At 3 min of incubation with [3H]PAF and [3H]lyso-PAF, control PMN had small but significant amounts of [3H]alkyl-acyl-GPC containing tetraenoic fatty acids, the concentration of which gradually increased as the incubation time progressed. On the other hand, under similar conditions, 20:4-depleted PMN had only trace amounts of the [3H]alkyl-acyl-GPC with tetraenoic fatty acid and the concentration of which remained at the low level throughout the incubation time. At 3 min of incubation, the 20:4-depleted PMN had small but significant amounts of [3H]alkyl-acyl-GPC with saturated fatty acids, the amount of which declined by 10 min and remained at that level as the incubation time progressed. While the concentration of [3H]alkyl-acyl-GPC with dienoic fatty acids in the 20:4-depleted cells gradually increased with the progress of incubation time, these molecular species of GPC in the control PMN remained more or less constant. In spite of a very high concentration (equivalent to that of 20:4 in control PMN) of eicosatrienoic acid (20:3 delta 5,8,11) in the 20:4-depleted PMN, no significant amounts of [3H]alkyl-acyl-GPC with trienoic fatty acid were formed by these cells. The rate of metabolism of [3H]PAF and [3H]lyso-PAF by the resident macrophages isolated from control and 20:4-depleted rats was similar.(ABSTRACT TRUNCATED AT 400 WORDS)
1 - O - [³H]烷基 - 2 - 乙酰基 - sn - 甘油 - 3 - 磷酸胆碱（[³H]PAF）和1 - O - [³H]烷基 - 2 - 溶血 - sn - 甘油 - 3 - 磷酸胆碱（[³H]溶血 - PAF）与大鼠多形核白细胞（PMN）一起孵育时，会迅速代谢为在sn - 2位含有长链酰基的1 - O - [³H]烷基 - 2 - 酰基 - sn - 甘油 - 3 - 磷酸胆碱（[³H]烷基 - 酰基 - GPC）。通过比较对照大鼠PMN与耗尽20:4的大鼠PMN对[³H]PAF和[³H]溶血 - PAF的代谢速率，研究了花生四烯酸（20:4）对PAF和溶血 - PAF酰化的特异性和绝对需求。在研究的所有PAF和溶血 - PAF浓度下，对照和耗尽20:4的PMN对[³H]PAF和[³H]溶血 - PAF的代谢速率相当。通过银染色谱分析掺入到所形成的[³H]烷基 - 酰基 - GPC的sn - 2位的脂肪酰基的性质。在所有研究的孵育时间，二烯脂肪酸是对照和耗尽20:4的PMN掺入到烷基 - 酰基 - GPC中的主要脂肪酸。在用[³H]PAF和[³H]溶血 - PAF孵育3分钟时，对照PMN含有少量但显著量的含有四烯脂肪酸的[³H]烷基 - 酰基 - GPC，其浓度随着孵育时间的延长而逐渐增加。另一方面，在类似条件下，耗尽20:4的PMN仅含有痕量的含有四烯脂肪酸的[³H]烷基 - 酰基 - GPC，并且其浓度在整个孵育时间内保持在低水平。在孵育3分钟时，耗尽20:4的PMN含有少量但显著量的含有饱和脂肪酸的[³H]烷基 - 酰基 - GPC，其含量在10分钟时下降，并随着孵育时间的延长保持在该水平。虽然耗尽20:4的细胞中含有二烯脂肪酸的[³H]烷基 - 酰基 - GPC的浓度随着孵育时间的延长而逐渐增加，但对照PMN中这些GPC分子种类或多或少保持恒定。尽管耗尽20:4的PMN中二十碳三烯酸（20:3Δ5,8,11）的浓度非常高（相当于对照PMN中20:4的浓度），但这些细胞未形成显著量的含有三烯脂肪酸的[³H]烷基 - 酰基 - GPC。从对照和耗尽20:4的大鼠分离的驻留巨噬细胞对[³H]PAF和[³H]溶血 - PAF的代谢速率相似。（摘要截短至400字）
