Yu Dao-Yi, Su Er-Ning, Cringle Stephen J, Morgan William H, McAllister Ian L, Yu Paula K
Invest Ophthalmol Vis Sci. 2016 Feb;57(2):412-9. doi: 10.1167/iovs.15-18358.
To determine whether vascular tone of isolated porcine retinal veins can be modulated by tissue-generated vasoactive factors such as endothelin-1 and adenosine. Such information may be useful in understanding the role of the retinal veins in regulating blood flow, and also provide a model for investigating new hypotheses suggesting a role for vasoactive factors in retinal vascular diseases such as retinal vein occlusion.
An isolated perfused retinal vein preparation was used for this study. Segments of porcine retinal veins were dissected, cannulated, and perfused, and their diameter was monitored during vasoactive agent application of increasing doses of endothelin-1 (10(-12)-10(-8) M) or adenosine (10(-10)-10(-4) M). Adenosine (10(-6) M) was also applied on veins during preconstriction with endothelin-1 (10(-8) M). The significance of any induced change in vessel diameter was assessed in relation to the baseline vessel diameter prior to any drug delivery.
Dose-dependent vasocontractile responses were induced by endothelin-1 administration. Endothelin-1 produced a significant contraction at doses of 10-11 M and above. At 10(-8) M the maximal endothelin-1-induced contractions were to 70.2 ± 2.1% of baseline. Adenosine produced a dose-dependent dilation reaching 113.0 ± 2.4% at 10(-4) M. Adenosine (10(-6) M) induced a significant dilation in endothelin-1 (10(-8) M)-contracted vessels.
Porcine retinal veins can be modulated by both vasocontraction and vasodilation agents, suggesting that the retinal veins may play a regulatory role in the retinal circulation, particularly in regard to the capillary pressure upstream from the draining retinal veins. To our knowledge, this is the first study of vasoactivity in isolated perfused retinal veins, providing an opportunity to study the direct vasoactive effects of specific vasoactive agents.
确定分离的猪视网膜静脉的血管张力是否可被组织产生的血管活性因子（如内皮素 -1 和腺苷）调节。此类信息可能有助于理解视网膜静脉在调节血流中的作用，也为研究血管活性因子在诸如视网膜静脉阻塞等视网膜血管疾病中作用的新假说提供一个模型。
本研究采用分离灌注的视网膜静脉制备方法。解剖猪视网膜静脉段，插管并进行灌注，在应用递增剂量的内皮素 -1（10⁻¹² - 10⁻⁸ M）或腺苷（10⁻¹⁰ - 10⁻⁴ M）等血管活性药物期间监测其直径。在使用内皮素 -1（10⁻⁸ M）进行预收缩时，也将腺苷（10⁻⁶ M）应用于静脉。相对于任何药物给药前的基线血管直径，评估所诱导的血管直径变化的显著性。
内皮素 -1 给药诱导剂量依赖性血管收缩反应。内皮素 -1 在 10⁻¹¹ M 及以上剂量时产生显著收缩。在 10⁻⁸ M 时，内皮素 -1 诱导的最大收缩达到基线的 70.2 ± 2.1%。腺苷产生剂量依赖性扩张，在 10⁻⁴ M 时达到 113.0 ± 2.4%。腺苷（10⁻⁶ M）在内皮素 -1（10⁻⁸ M）收缩的血管中诱导显著扩张。
猪视网膜静脉可被血管收缩剂和血管舒张剂调节，这表明视网膜静脉可能在视网膜循环中起调节作用，特别是在引流视网膜静脉上游的毛细血管压力方面。据我们所知，这是首次对分离灌注的视网膜静脉血管活性进行的研究，为研究特定血管活性药物的直接血管活性作用提供了机会。
