Bastyr E J, Kadrofske M M, Vinik A I
Department of Internal Medicine, University of Michigan, Ann Arbor.
Am J Med. 1990 Jun;88(6):601-6. doi: 10.1016/0002-9343(90)90525-i.
Blood platelet activity increases with advancing age. This study was designed to determine if changes in a key signal-transducing mechanism in the platelet, phosphoinositide turnover, are associated with the enhanced platelet activity seen in aging.
Platelets were harvested from a total of 40 healthy, non-obese, 22- to 62-year-old individuals, free of any clinical evidence of atherosclerotic vascular disease, and having normal serum laboratory lipid levels. Studies of platelet activity included measurement of in vitro platelet aggregation and plasma beta-thromboglobulin (beta-TBG), a marker of in vivo platelet secretion. Basal and thrombin-stimulated phosphoinositide turnover was measured following [32P]-orthophosphate incorporation into the various phospholipids, isolation of the phosphoinositides and phosphatidic acid by thin-layer chromatography and autoradiography, and quantification by liquid scintillation spectroscopy of these radiolabeled phospholipids.
There was a positive correlation with age for both adenosine diphosphate (ADP)-induced aggregation (1.25 microM, r = 0.464, p less than 0.001; 2.5 microM, r = 0.386, p less than 0.05) and plasma beta-TBG (r = 0.381, p less than 0.055). There was a time-dependent increase of [32P]orthophosphate (32Pi) incorporation into platelet phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 4-phosphate (PIP), and isotopic equilibrium was reached by 120 minutes at 37 degrees C. A positive correlation was found between age and basal 32P-PIP2 (r = 0.640, p less than 0.001) and 32P-PIP (r = 0.676, p less than 0.0005). Basal 32Pi incorporation into PIP2 correlated positively with in vitro aggregation (1.25 microM ADP, r = 0.795, p less than 0.0001; 2.5 microM ADP, r = 0.755, p less than 0.0005) as did 32Pi incorporation into PIP (1.25 microM ADP, r = 0.815, p less than 0.0001; 2.5 microM ADP, r = 0.795, p less than 0.0001). There was also a positive correlation between plasma beta-TBG levels and basal 32P-PIP2 (r = 0.768, p less than 0.005) and 32P-PIP (r = 0.505, p less than 0.066). Finally, increasing age correlated with thrombin (4 U/mL)-stimulated 32P-PIP2 hydrolysis (r = 0.694, p less than 0.01) and phosphatidic acid formation (r = 0.556, p less than 0.05).
血小板活性随年龄增长而增加。本研究旨在确定血小板中关键信号转导机制——磷酸肌醇代谢的变化是否与衰老过程中血小板活性增强有关。
从40名年龄在22至62岁之间、健康、非肥胖且无动脉粥样硬化性血管疾病临床证据、血清实验室血脂水平正常的个体中采集血小板。血小板活性研究包括体外血小板聚集测定和血浆β-血小板球蛋白（β-TBG）测定，β-TBG是体内血小板分泌的标志物。在将[32P]-正磷酸盐掺入各种磷脂后，通过薄层色谱和放射自显影分离磷酸肌醇和磷脂酸，并用液体闪烁光谱法对这些放射性标记的磷脂进行定量，从而测定基础和凝血酶刺激的磷酸肌醇代谢。
二磷酸腺苷（ADP）诱导的聚集（1.25微摩尔，r = 0.464，p < 0.001；2.5微摩尔，r = 0.386，p < 0.05）和血浆β-TBG（r = 0.381，p < 0.055）均与年龄呈正相关。[32P]正磷酸盐（32Pi）掺入血小板磷脂酰肌醇4,5-二磷酸（PIP2）和磷脂酰肌醇4-磷酸（PIP）呈时间依赖性增加，在37℃下120分钟达到同位素平衡。年龄与基础32P-PIP2（r = 0.640，p < 0.001）和32P-PIP（r = 0.676，p < 0.0005）呈正相关。基础32Pi掺入PIP2与体外聚集呈正相关（1.25微摩尔ADP，r = 0.795，p < 0.0001；2.5微摩尔ADP，r = 0.755，p < 0.0005），32Pi掺入PIP也是如此（1.25微摩尔ADP，r = 0.815，p < 0.0001；2.5微摩尔ADP，r = 0.795，p < 0.0001）。血浆β-TBG水平与基础32P-PIP2（r = 0.768，p < 0.005）和32P-PIP（r = 0.505，p < 0.066）也呈正相关。最后，年龄增长与凝血酶（4 U/mL）刺激的32P-PIP2水解（r = 0.694，p < 0.01）和磷脂酸形成（r = 0.556，p < 0.05）相关。
