Clozel J P, Amend P, Saunier C, Hartemann D
Crit Care Med. 1985 Nov;13(11):976-81. doi: 10.1097/00003246-198511000-00040.
Cimetidine is an H2 receptor-blocking drug frequently given to ICU patients for the prevention of stress ulcers. However, histamine causes potent cerebral vasodilation through the H2 receptors. This study tested the hypothesis that cimetidine, by blocking the H2 receptors, could blunt the increase of cerebral blood flow induced by hypoxia. We induced isocapnic hypoxia in 12 conscious dogs that were randomly divided into two groups. Six dogs received no treatment (control group), and the other six received iv cimetidine (4 mg/kg) to block the H2 receptors. Cerebral blood flow (CBF) was measured with the radioactive microsphere technique before, and 2 and 4 h after hypoxia was induced. In the control group, CBF significantly increased with hypoxia in all the regions of the brain. Cimetidine blunted this increase in all the regions of the brain except the pons and bulb. As a result of the reduced flow, cimetidine significantly decreased the oxygen supply to the brain compared to the control group. We conclude that cimetidine blunts the increase in CBF during hypoxia and might reduce oxygen supply to the brain in hypoxic patients.
西咪替丁是一种H2受体阻断药物，常用于重症监护病房（ICU）患者以预防应激性溃疡。然而，组胺通过H2受体引起强烈的脑血管舒张。本研究检验了这样一个假设，即西咪替丁通过阻断H2受体，可能会减弱缺氧诱导的脑血流量增加。我们对12只清醒犬诱导等碳酸血症性缺氧，并将其随机分为两组。6只犬不接受治疗（对照组），另外6只静脉注射西咪替丁（4mg/kg）以阻断H2受体。在诱导缺氧前以及诱导后2小时和4小时，用放射性微球技术测量脑血流量（CBF）。在对照组中，缺氧时脑内所有区域的CBF均显著增加。西咪替丁使脑内除脑桥和延髓外的所有区域的这种增加减弱。由于血流量减少，与对照组相比，西咪替丁显著降低了脑的氧供应。我们得出结论，西咪替丁减弱了缺氧时CBF的增加，并且可能会减少缺氧患者脑的氧供应。
