Shirai M, Sada K, Ninomiya I
Department of Cardiac Physiology, National Cardiovascular Center Research Institute, Osaka, Japan.
J Appl Physiol (1985). 1988 Jul;65(1):288-96. doi: 10.1152/jappl.1988.65.1.288.
The pulmonary vascular bed was embolized with glass beads in small doses that induced no significant changes in pulmonary arterial pressure in anesthetized cats. We analyzed changes in internal diameter (ID), flow velocity, and volume flow of embolized and nonembolized arteries simultaneously with ID changes of small veins. In embolized arteries, with 180-, 300-, and 500-microns beads, ID constricted maximally in just proximal portions of the plug by 22, 23, and 17%, respectively, but with 840-microns beads, no ID constriction occurred. With 50-microns beads, the maximum ID constriction occurred in arteries of 200-300 microns but not in those of 100-200 microns. The constriction decreased in the upstream larger arteries and disappeared in those greater than 800 microns ID. In the nonembolized arteries no ID change occurred. Veins constricted slightly compared with arteries. By heparin pretreatment, ID constriction was slightly attenuated in arteries and was almost abolished in veins, whereas it was not affected with hexamethonium bromide. At a branching site, volume flow to an embolized artery decreased because of a decrease in ID and flow velocity, whereas volume flow to a nonembolized artery increased because of an increase in flow velocity. We concluded that pulmonary microembolization induced a vasoconstriction chiefly in small pulmonary arteries upstream to the plug. After embolization, blood flow was locally redistributed from an embolized to a nonembolized artery at a branching site. Arterial vasoconstriction may be mediated chiefly by local mechanical factors.
在麻醉猫身上，用小剂量玻璃珠栓塞肺血管床，这些剂量不会引起肺动脉压的显著变化。我们同时分析了栓塞动脉和未栓塞动脉的内径（ID）、流速和容积流量的变化以及小静脉内径的变化。在栓塞动脉中，使用180微米、300微米和500微米的珠子时，内径在栓塞物近端部分分别最大收缩22%、23%和17%，但使用840微米的珠子时，未出现内径收缩。使用50微米的珠子时，最大内径收缩发生在200 - 300微米的动脉中，而在100 - 200微米的动脉中未出现。收缩在栓塞物上游的较大动脉中减小，在内径大于800微米的动脉中消失。在未栓塞动脉中，内径未发生变化。与动脉相比，静脉略有收缩。通过肝素预处理，动脉内径收缩略有减弱，静脉内径收缩几乎消失，而六甲溴铵对此无影响。在分支部位，由于内径和流速降低，流向栓塞动脉的容积流量减少，而由于流速增加，流向未栓塞动脉的容积流量增加。我们得出结论，肺微栓塞主要在栓塞物上游的小肺动脉中引起血管收缩。栓塞后，在分支部位血流从栓塞动脉局部重新分布到未栓塞动脉。动脉血管收缩可能主要由局部机械因素介导。
