内皮细胞衍生的一氧化氮抑制凝血酶激活的兔血小板Na^+/H^+交换(英文)

Nitric oxide derived from endothelial cells inhibits Na^+ /H^+ exchange in rabbit platelets activated by thrombin

目的:探讨内皮细胞衍生的NO对凝血酶激活的血小板内Na^+/H^+交换的影响,方法:荧光双波长比值法,结果:内皮细胞(0.1-1×10~9·L^(-1))数量依赖地抑制凝血酶诱导的血小板聚集,硝基精氨酸1 mmol·L^(-1)可取消这种作用,用依他酸及ionomycin耗竭细胞内钙池,凝血酶诱导的血小板胞浆碱化被取消,重新充填细胞内钙池部分恢复,内皮细胞(2×10~8·L^(-1))显著抑制凝血酶诱导的兔血小板pH_i升高及内钙释放,结论:血管内皮细胞衍生的NO抑制凝血酶诱导的血小板活化是通过抑制凝血酶诱导的血小板内钙动员,继而抑制Na^+/H^+交换的激活来介导的。

AIM: To study the effect of nitric oxide (NO) derived from endothelial cells on Na+/H+ exchange in rabbit platelets activated by thrombin. METHODS: Intracellular Ca2+ ([Ca2+ ]i) and intracellular pH (pHi) were measured by the dual-wavelength fluorophotometer with the fluorescent probes Fura-2 and 2', 7'-biscarb-oxvethyl-5,6-carboxyfluorescein (BCECF). Effects or NO on rabbit platelets were tested by cultured bovine endothelial cells (BAEC). RESULTS: BAEC (0.1 -1× 109·L-1) inhibited thrombin (100 U·L-1)-induced platelet aggregation in a concentration-dependent manner. This inhibiting effect was abolished by preincubating BAEC with NG-nitro-L-arginine 1 mmol·L-1. When the [Ca2+ ]i store was depleted with ionomycin in the presence of egtazic acid (EGTA), the increase in pHi induced by thrombin was inhibited. Refilling intracellular Ca2+ store partially reversed this effect. BAEC 2×108·L-1 inhibited thrombin (100 U· L-1)-induced elevation of pHi and mobilization of intracellular Ca2+ store ( P < 0.01). No direct effect of endothelial cells on unstimulated rabbit platelets was observed. CONCLUSION: NOderived from endothelial cells inhibited thrombin-induced rabbit platelet activation by inhibiting thrombin-induced [Ca2+ ]i mobilization and then inhibiting the consequent Na+/H+ exchange in rabbit platelets.