Wang Lin, Fortune Brad, Cull Grant, McElwain Kyle M, Cioffi George A
Discoveries in Sight, Devers Eye Institute, 1225 NE 2nd Ave, Portland, OR 97208, USA.
Exp Eye Res. 2007 Jan;84(1):108-17. doi: 10.1016/j.exer.2006.09.005. Epub 2006 Oct 25.
This study modified the microspheres method by optimizing the dose and size of microspheres (MS) to enable accurate ocular blood flow measurement in rats. Fluorescent MS, either 6, 8, 10 or 15 microm diameter, were administered into the left ventricle of anesthetized adult Brown Norway rat in a dose of either 10(6), 5x10(6), or 10(7). The total number of MS entrapped in retina, choroid and optic nerve (Ntissue) was quantified and compared between size and dose groups. The MS distribution in the retina and their reentry into systemic circulation were evaluated for different sized MS. The results showed that at the 5x10(6) dose, the Ntissue of 8 microm MS was significantly more than either 6 or 10 microm MS in the retina (P<0.02) and optic nerve (P<0.03). The 10 microm MS produced the highest Ntissue for the choroid, as compared with either 8 or 6 microm MS (P<0.03). At the 10(6) dose, no difference of N(tissue) was found between 8, 10, and 15 microm MS in the retina. The 10 microm MS yielded the highest Ntissue in the choroid as compared to 8 and 15 microm MS (P<0.003). The Ntissue for 8 microm MS was higher than both 10 and 15 microm (P<0.01) MS in the optic nerve. No MS (>or=8 microm) reentered the systemic circulation. The 15 microm MS tended to lodge in pre-capillary arterioles and caused significant blood pressure increase during the injection. The blood flow measured with the optimal size MS (mean+/-SE) were 19+/-3.4 and 170+/-35 microl/min in the retina and choroid, respectively; and 0.18+/-0.03 microl/min per mm optic nerve. It is concluded that the 8 microm MS are the optimal size for both retinal and optic nerve blood flow estimation; the 10 microm for the choroid. The optimal dose for the retina was approximately 2.5x10(6), 0.5x10(6) for the choroid, and 5x10(6) approximately 10(7) for the optic nerve. The 15 microm MS are inappropriate for ocular blood flow measurements in rats.
本研究通过优化微球（MS）的剂量和大小对微球法进行了改进，以实现对大鼠眼部血流的精确测量。将直径为6、8、10或15微米的荧光微球，以10⁶、5×10⁶或10⁷的剂量注入麻醉的成年棕色挪威大鼠的左心室。对捕获在视网膜、脉络膜和视神经中的微球总数（N组织）进行定量，并在大小和剂量组之间进行比较。评估了不同大小微球在视网膜中的分布及其重新进入体循环的情况。结果表明，在5×10⁶的剂量下，8微米微球在视网膜（P<0.02）和视神经（P<0.03）中的N组织明显多于6微米或10微米的微球。与8微米或6微米的微球相比，10微米的微球在脉络膜中产生的N组织最高（P<0.03）。在10⁶的剂量下，视网膜中8、10和15微米的微球在N（组织）上没有差异。与8微米和15微米的微球相比，10微米的微球在脉络膜中产生的N组织最高（P<0.003）。8微米微球在视神经中的N组织高于10微米和15微米（P<0.01）的微球。没有微球（≥8微米）重新进入体循环。15微米的微球倾向于滞留在毛细血管前小动脉中，并在注射过程中导致血压显著升高。用最佳大小的微球测量的视网膜和脉络膜血流（平均值±标准误）分别为19±3.4和170±35微升/分钟；视神经为0.18±0.03微升/分钟·毫米。结论是，8微米的微球是估计视网膜和视神经血流的最佳大小；10微米的微球适用于脉络膜。视网膜的最佳剂量约为2.5×10⁶，脉络膜为0.5×10⁶，视神经约为5×10⁶至10⁷。15微米的微球不适用于大鼠眼部血流测量。
