急性低压缺氧时TXA_2、PGI_2的变化及其与脑血流量变化的关系

Roles of thromboxane A_2 and prostacyclin in change of cerebral bood flow during acute hypoxia

目的探讨急性低压缺氧时血栓素A2(TXA2)和前列环素(PGI2)的变化及其与脑血流量变化的关系。方法将20只大鼠随机分为常氧对照组(n=10)和急性低压缺氧组(n=10),用电磁血流量计测定脑血流量,用放免法分别测量TXA2、PGI2的含量。由于TXA2和PGI2的不稳定性,目前推以直接测定,故国内外均以测定其代谢产物TXB2、6-keto-PGF1α作为判断其浓度的指标。结果急性低压缺氧时脑血流量、脑含水量、血浆、脑组织TXB2含量、脑组织TXB2/6-keto-PGF1α比值明显增高(P<0.05),6-keto-PGF1α无明显变化。结论急性低压缺氧时,TXA2、脑血流量均增加,TXA2参与了急性低压缺氧时脑血流量的调节,可能以抑制脑血管过度扩张作用为主。

Objective The article was to investigate the roles of thromboxane A2（TXA2） and prostacyclin（PGI2） in change of cerebral blood flow（CBF） during acute hypoxia. Methods Rats were divided into normoxic group（Control） and acute hypoxia（AH） group. CBF were measured by electromagnetic blood flowmeter; due to the instability of TXA2 and PGI2, at present it is difficult to directly measurment,so at home and abroad in order to measure its metabolites TXB2、6-ketoPGF1ɑas its concentration index,so the changes of TXB2、6-keto-PGF1ɑcontents were measured by radioimmunoassay.Result Acute hypoxia caused an increase in CBF, plasma,brain TXB2 contents and the ratio of TXB2/ 6-keto-PGF1αin the brain, but plasma and brain 6-keto-PGF1ɑwere not changed, as compared with the control group. Conclusion TXA2 and CBF increased in acute hypoxia,TXA2 may be involved in the regulation of CBF, but TXA2 may be suppress the excessive expansion of cerebral vascular.