Studies on responsiveness of rat retial blood vessels with a newly developed digital funduscope system for small animals

视网膜小动脉和小静脉只是中央血管，不需要任何手术就可以从体外直接观察到。为了研究大鼠视网膜血管的反应性，我们建立了一种新的数字眼底镜系统，该系统包括一个装有410,000像素CCD的摄像机和一个特殊的物镜，用于观察小动物的视网膜，如大鼠、豚鼠、兔等。股动脉和股静脉分别置入聚乙烯管监测动脉压(AP)、心率和给药。视网膜的图像由数字眼底镜捕捉并记录在数字录像带上。尼卡地平(1~30μg/kg)可使AP降低，DV升高。硝苯地平(10-100μg/kg)可降低AP，但不影响DV。氟桂利嗪(1~30μg/kg)不改变AP，但增加DV。异丁司特(0.1-1.0 mg/kg)和长春西汀(0.1-1.0 mg/kg)增加DV，但对AP无影响。这些数据表明，我们新开发的实验系统可以监测药物对大鼠DV的变化。由于视网膜和脑血管在许多方面是相似的，我们的方法可能有助于筛选不仅改变视网膜而且改变大脑循环的药物。

Retinal arterioles and venules are only central blood vessels that can be observed directly from outside of the body without any surgical procedures. To investigate responsiveness of these blood vessels of the rat, we established a new digital funduscope system that includes a video camera equipped with a 410,000-pixel CCD and a special objective lens for observation of the retina of small animals, such as rats, guinea pigs, rabbits, etc..Male Wistar rats were anesthetized with urethane or sodium thiobutabarbital. Polyethylene cannulae were inserted into femoral artery and femoral vein to monitor arterial pressure (AP) and heart rate and to administer drugs, respectively. Images of the retina were captured by a digital funduscope and recorded on a digital video tape. Changes in diameters of retinal blood vessels (DV) induced by various vasoactive drugs were calculated on a personal computer after making some graphic effects.Nicardipine (1-30μg/kg) lowered AP and increased DV. Nifedipine (10-100μg/kg) lowered AP, but did not affect DV. Flunarizine (1-30μg/kg) did not change AP, but increased DV. Ibudilast (0.1-1.0 mg/kg) and vinpocetine (0.1-1.0 mg/kg) increased DV without any effect on AP.These data demonstrate that changes in DV of rats in response to drugs can be monitored by our newly developed experimental system. Since retinal and cerebral blood vessels are similar in many aspects, our method might be useful for screening of drugs that alter not only retinal but also cerebral circulation.