Russo Isabella, Del Mese Paola, Doronzo Gabriella, De Salve Alessandro, Secchi Mariantonietta, Trovati Mariella, Anfossi Giovanni
Diabetes Unit, Department of Clinical and Biological Sciences of University of Turin, San Luigi Gonzaga Hospital, Orbassano (Turin), Italy.
Clin Chem. 2007 Jun;53(6):1053-60. doi: 10.1373/clinchem.2006.076208. Epub 2007 Apr 26.
Impairment of platelet response to antiaggregatory agents is seen in individuals with central obesity and may play a role in the increased cardiovascular risk associated with obesity. In this study we evaluated whether this impairment involves the antiaggregatory pathways regulated by cAMP and cGMP.
We obtained platelet-rich plasma from 12 obese individuals and 12 controls. We investigated the effects of the cyclic nucleotide analogs 8-pCPT-cAMP (10-500 micromol/L) and 8-pCPT-cGMP (10-500 micromol/L) on ADP-induced platelet aggregation as assessed by decreased light scattering. We assessed the activation of cAMP- and cGMP-dependent protein kinases by measuring phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) at Ser157 and Ser239.
The antiaggregatory effect of both cyclic nucleotide analogs was impaired in obese individuals compared to controls, with mean (SE) half-maximal inhibitory concentrations (IC(50)) (after 20-min incubation) of 123 (33) micromol/L vs 5 (1) micromol/L, respectively, for 8-pCPT-cAMP (P <0.01) and of 172 (43) micromol/L vs 17 (8) micromol/L, respectively, for 8-pCPT-cGMP (P <0.01). The Homeostasis Model Assessment Index of Insulin Resistance was independently correlated with cyclic nucleotide analog IC(50). In obese individuals, VASP phosphorylation at Ser157 and Ser239 in response to cyclic nucleotides was significantly lower than in controls.
In central obesity the reduced ability of cyclic nucleotides to inhibit platelet aggregation is associated with reduced activation of their specific kinases. Because cyclic nucleotides help regulate platelet antiaggregation, alteration of this ability is consistent with platelet hyperactivity in obesity.
中心性肥胖个体存在血小板对抗聚集剂反应受损的情况，这可能在肥胖相关的心血管风险增加中起作用。在本研究中，我们评估了这种受损是否涉及由环磷酸腺苷（cAMP）和环磷酸鸟苷（cGMP）调节的抗聚集途径。
我们从12名肥胖个体和12名对照者中获取富含血小板的血浆。我们研究了环核苷酸类似物8-对氯苯硫基-cAMP（10 - 500微摩尔/升）和8-对氯苯硫基-cGMP（10 - 500微摩尔/升）对二磷酸腺苷（ADP）诱导的血小板聚集的影响，通过光散射减少来评估。我们通过测量血管舒张刺激磷蛋白（VASP）在丝氨酸157和丝氨酸239位点的磷酸化来评估cAMP和cGMP依赖性蛋白激酶的激活。
与对照者相比，肥胖个体中环核苷酸类似物的抗聚集作用均受损，8-对氯苯硫基-cAMP（孵育20分钟后）的平均（标准误）半数最大抑制浓度（IC50）分别为123（33）微摩尔/升和5（1）微摩尔/升（P <0.01），8-对氯苯硫基-cGMP分别为172（43）微摩尔/升和17（8）微摩尔/升（P <0.01）。胰岛素抵抗的稳态模型评估指数与环核苷酸类似物的IC50独立相关。在肥胖个体中，环核苷酸刺激下VASP在丝氨酸157和丝氨酸239位点的磷酸化显著低于对照者。
在中心性肥胖中，环核苷酸抑制血小板聚集的能力降低与其特异性激酶的激活减少有关。由于环核苷酸有助于调节血小板抗聚集，这种能力的改变与肥胖中血小板的高活性一致。
