Fan F C, Schuessler G B, Chen R Y, Chien S
Am J Physiol. 1979 Jul;237(1):H25-33. doi: 10.1152/ajpheart.1979.237.1.H25.
In 17 pentobarbitalized dogs, the shunting of 15-micrometer and 9-micrometer microspheres was studied in the brain, myocardium, kidney, intestine, and lung. The veins of these organs were catheterized for constant blood withdrawal for 2 min by direct venipuncture. The ratio of microsphere radioactivity in the venous blood to that in the arterial blood gave the shunting of microspheres by the venous sampling technique. The 15-micrometer microspheres showed 2% or less shunting for all organs studied, whereas the 9-micrometer microspheres had shunting ranging from 3% in the coronary sinus to 24% in the portal vein. The shunting of 9-micrometer microspheres was also calculated from direct tissue counting, where the 15-micrometer spheres were considered to be completely entrapped. The results of direct tissue counting indicate that the 2-min venous sampling underestimates microsphere shunting. CO2 administration increased significantly the shunting of 9-micrometer spheres, whereas the shunting of 15-micrometer spheres determined by venous sampling remained less than 2%. Consideration of shunting indicates that the 15-micrometer microspheres might be more appropriate for regional organ blood flow measurements, including the myocardium.
在17只戊巴比妥麻醉的狗身上，研究了15微米和9微米微球在脑、心肌、肾、肠和肺中的分流情况。通过直接静脉穿刺将这些器官的静脉插管，持续采血2分钟。静脉血中微球放射性与动脉血中微球放射性的比值，通过静脉采样技术得出微球的分流情况。对于所有研究的器官，15微米的微球显示分流率为2%或更低，而9微米的微球分流率范围从冠状窦的3%到门静脉的24%。9微米微球的分流情况也通过直接组织计数来计算，其中15微米的微球被认为完全滞留。直接组织计数的结果表明，2分钟的静脉采样低估了微球的分流情况。给予二氧化碳显著增加了9微米微球的分流，而通过静脉采样确定的15微米微球的分流仍小于2%。对分流情况的考虑表明，15微米的微球可能更适合用于包括心肌在内的区域器官血流测量。
