Schuette A H, Hüttemeier P C, Hill R D, Watkins W D, Wonders T R, Kong D, Zapol W M
Surgery. 1984 Apr;95(4):444-53.
Fifteen minutes after intravenous Escherichia coli endotoxin (EN) infusion the sheep lung transiently releases into the systemic circulation up to 12 micrograms of thromboxane A2 (TxA2)/min measured by radioimmunoassay as its metabolite thromboxane B2 (TxB2). To determine whether lung thromboxane release alters regional blood flow (RBF) we injected microspheres before and 20, 30, and 100 minutes after EN infusion in 13 awake sheep. In seven untreated control sheep (group 1) pulmonary vascular resistance (PVR) increased threefold at 20 and 30 minutes after EN infusion, coinciding with a large transpulmonary blood concentration gradient of TxB2. There was no measured RBF change to any systemic tissue or organ except the right ventricle at 20 minutes after EN infusion, when blood flow per gram of tissue doubled. In six sheep (group 2) treated with intravenous ibuprofen before EN infusion there was no increase in PVR, plasma TxB2, or blood flow to the right ventricle, and no difference of RBF to any other organ or tissue when compared to group 1. TxA2 is a potent local pulmonary vasoconstrictor but it rapidly hydrolyzes. Its short half-life and the circulatory delay in systemic arterial delivery prevent TxA2 from acting as a circulating vasoconstrictor.
静脉注射大肠杆菌内毒素（EN）15分钟后，绵羊肺脏会以其代谢产物血栓素B2（TxB2）的形式，通过放射免疫测定法测定，以每分钟高达12微克的速度短暂释放血栓素A2（TxA2）进入体循环。为了确定肺血栓素的释放是否会改变局部血流量（RBF），我们在13只清醒的绵羊静脉注射EN之前、之后20、30和100分钟注射了微球。在7只未治疗的对照绵羊（第1组）中，EN注射后20和30分钟时肺血管阻力（PVR）增加了两倍，这与TxB2的大跨肺血浓度梯度一致。除了在EN注射后20分钟时右心室每克组织血流量增加一倍外，未检测到任何全身组织或器官的RBF变化。在6只（第2组）在EN注射前静脉注射布洛芬治疗的绵羊中，PVR、血浆TxB2或右心室血流量没有增加，与第1组相比，任何其他器官或组织的RBF也没有差异。TxA2是一种强力的局部肺血管收缩剂，但它会迅速水解。其短半衰期和全身动脉输送中的循环延迟阻止了TxA2作为循环血管收缩剂发挥作用。
