Lamers J M, Dekkers D H, De Jong N, Meij J T
Department of Biochemistry, Faculty of Medicine and Health Sciences, Erasmus University Rotterdam, The Netherlands.
J Mol Cell Cardiol. 1992 Jun;24(6):605-18. doi: 10.1016/0022-2828(92)91045-7.
Cultured neonatal cardiac myocytes have been utilized as a model for the study of the role of fatty acids in the alpha 1-adrenoceptor mediated phosphatidylinositol turnover. Experiments were started 24 h after seeding, when there was a confluent monolayer of beating cardiomyocytes. The cells were incubated for 3-4 days in sera containing culture medium with (1) no additives or (2) a mixture of 107 microM 18:0 and 18:1n-9, or (3) only 214 microM 18:2n-6 or (4) 214 microM 20:5n-3. No differences in the cellular content of the various phospholipid classes among the different groups of fatty acid treated cells were found. The predicted elevations of 18:1n-9, 18:2n-6 and 20:5n-3 associated with a partial depletion of 20:4n-6 were confirmed in all phospholipid classes, except for sphingomyelin. The mol% of 18:0, 18:2n-6, 20:4n-6 and 20:5n-3 in the phosphatidylinositol fraction were respectively 39, 4, 30 and 0.6 for the control treated cells, 34, 3, 15 and 0 for 18:0/18:1n-9 treated cells, 40, 17, 24 and 0.2 for the 18:2n-6 treated cells and 41, 3, 13 and 21 for the 20:5n-3 treated cells. Apart from the observed reductions in the basal rates, the phenylephrine (30 microM) stimulated production of inositolphosphates was reduced by 51% and 71%, respectively in the 18:2n-6 and 20:5n-3 treated cardiomyocytes. The basal rate of inositolphosphate formation was 37% increased in the 18:0/18:1n-9 treated cells. The [3H]-inositol incorporation into phosphatidylinositol 4,5-bisphosphate was only slightly reduced by 18:2n-6 and 20:5n-3 treatments (respectively 12 and 28% compared to control treated cells). Prolonged (30 min) alpha 1-adrenergic stimulation did not affect the contents and fatty acid profiles of any class of phospholipid, not even phosphatidylinositol. In conclusion, variations in the polyunsaturated fatty acid composition of membrane phospholipids do affect the basal and the alpha 1-adrenoceptor stimulated rate of phosphatidylinositol-4,5-bisphosphate hydrolysis. The reducing effects of 18:2n-6 and 20:5n-3 treatment on the rate of inositolphosphate production may be partially ascribed to altered levels of phosphatidyl-inositol 4,5-bisphosphate.
培养的新生大鼠心肌细胞已被用作研究脂肪酸在α1 - 肾上腺素能受体介导的磷脂酰肌醇代谢中作用的模型。接种后24小时开始实验，此时心肌细胞已形成汇合的单层。将细胞在含有培养基的血清中培养3 - 4天，培养基中分别添加：(1) 无添加剂；(2) 107 μM 18:0和18:1n - 9的混合物；(3) 仅214 μM 18:2n - 6；(4) 214 μM 20:5n - 3。在不同脂肪酸处理组的细胞中，未发现各类磷脂的细胞含量有差异。除鞘磷脂外，在所有磷脂类别中均证实了与20:4n - 6部分消耗相关的18:1n - 9、18:2n - 6和20:5n - 3的预期升高。对照处理细胞的磷脂酰肌醇组分中18:0、18:2n - 6、20:4n - 6和20:5n - 3的摩尔百分比分别为39、4、30和0.6；18:0/18:1n - 9处理细胞分别为34、3、15和0；18:2n - 6处理细胞分别为40、17、24和0.2；20:5n - 3处理细胞分别为41、3、13和21。除了观察到基础速率降低外，在18:2n - 6和20:5n - 3处理的心肌细胞中，去氧肾上腺素（30 μM）刺激产生的肌醇磷酸分别降低了51%和71%。在18:0/18:1n - 9处理的细胞中，肌醇磷酸形成的基础速率增加了37%。用18:2n - 6和20:5n - 3处理后，[3H] - 肌醇掺入磷脂酰肌醇4,5 - 二磷酸仅略有降低（分别比对照处理细胞降低12%和28%）。长时间（30分钟）的α1 - 肾上腺素能刺激不影响任何磷脂类别的含量和脂肪酸谱，甚至不影响磷脂酰肌醇。总之，膜磷脂中多不饱和脂肪酸组成的变化确实会影响磷脂酰肌醇 - 4,5 - 二磷酸水解的基础速率和α1 - 肾上腺素能受体刺激速率。18:2n - 6和20:5n - 3处理对肌醇磷酸产生速率的降低作用可能部分归因于磷脂酰肌醇4,5 - 二磷酸水平的改变。
