CHANGES IN CEREBROSPINAL MLCROC1RCULATION DURING AND AFTER ABDOMINAL AORTIC CROSS-CLAMPIN : AN UNDERLYING MECHANISM

戊巴比妥麻醉家兔，在颅窗准备中测量脑软膜血管直径。我们根据以下方案研究实验。(1)We研究主动脉阻断和开放对软脑膜血管直径的影响。虽然肾下主动脉阻断不影响软脑膜血管直径，但释放20分钟主动脉阻断导致软脑膜小动脉扩张，然后收缩。明显的收缩持续至少60 mm。(2)To为了阐明腹主动脉阻断期间和阻断后脑微循环变化的机制，我们研究了血栓素（Tx）A2受体拮抗剂塞拉司特或自由基清除剂依达拉奉是否会影响腹主动脉阻断后观察到的反应。塞曲司特和依达拉奉均显著减弱软膜小动脉的收缩。因此，这种血管收缩部分地通过在交叉夹释放期间和之后在缺血区域中产生的TxA2和自由基的洗脱而诱导。(3)We研究了血管活性剂如米力农、达罗酯或前列腺素E1对腹主动脉阻断后观察到的小动脉收缩的影响。临床剂量的米力农和colforsin daropate，但不是前列腺素El衰减后，交叉钳释放软脑膜小动脉的收缩。

Pentobarbital anesthetized rabbits were prepared for measurement of cerebral pial vessel diameter in a cranial window preparation. We investigated the experiments according to following protocols.(1)We studied the effect of aortic clamping and declamping on cerebral pial vessel diameter. Although infrarenal aortic cross-clamping did not affect pial vessel diameter, release of a 20-min aortic cross-clamp caused pial arterioles to dilate and then constrict. A significant constriction persisted for at least 60 mm.(2)To clarify the mechanism of changes in cerebral microcirculation during and after abdominal aortic cross-clamping, we examined whether seratorodast, a thromboxane (Tx) A2 receptor antagonist, or edaravone, a free radical scavenger, would affect the respose observed after abdominal aortic cross-clamping. Both seratrodast and edaravone significantly attenuated the constriction of pial arterioles. Thus such vasoconstriction is partly induced via a washout of the TxA2 and free radicals produced in the ischemic region during and after cross-clamp release.(3)We investigated the effect of vasoactive agents such as milrinone, colforsin daropate, or prostaglandin E1 on arteriolar constriction observed after abdominal aortic cross-clamping. Clinical dose of milrinone and colforsin daropate but not prostaglandin El attenuated the constriction of pial arterioles after cross-clamp release.