Development of high-resolution digital fundus camera for small animals and application of it to studies on analysis of responsiveness of retinal blood vessels

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12672116
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biological pharmacy
• Research Institution: Kitasato University
• Principal Investigator: ISHII Kunio Sch. of Pharmceut. Sci., Dpt. Of Mol. Pharmacol., Professor, 薬学部, 教授 (90137993)
• Co-Investigator(Kenkyū-buntansha): NAKAHARA Tsutomu Sch. of Pharmceut. Sci., Dpt. Of Mol. Pharmacol., Assist. Professor, 薬学部, 助手 (10296519)
• Project Period (FY): 2000 – 2001
• Keywords: rat / retinal arteriole / retinal venule / diabetes mellitus / hypertension / fundus camera / drug responsiveness / β-adrenergic receptors

Research Abstract

We succeeded in developing a high-resolution digital fundus camera for small experimental animals by coupling the objective lens of Scalar VMS-170 digital video camera and the body of Nikon D1 or D1x single-lens reflex digital still camera. A special connecting tube was made to connect both devices, to bring the focal plain of the objective lens just on the CCD with a concave lens and to illuminate the fundus with light guided with glass fibers from a lighting unit. With this camera, we were able to capture clear digital images of rat fundus composed of 2.7- or 5.5-million pixels. Resolving power of the camera was estimated less than 2μm indicating enough capacity for measurement of diameters of rat retinal blood vessels.
Responsiveness of rat retinal arterioles and venules to adrenergic agents, angiotensin II, serotonin, nitrovasodilators and calcium antagonists was examined under tetrodotoxin treatment and artificial ventilation. We found that, In streptozotocin-induced diabetic rats, dilator responses to β-adrenergic stimulation of retinal arterioles were greatly impaired, although responses to other agents were little affected.
In stroke-prone spontaneously hypertensive rats (SHR-SP), retinal arterioles were narrow by about 30% and dilator responses to nicardipine and fasudil of these blood vessels were augmented. As causes of this phenomenon, enhanced influx of Ca^<2+> and augmented Ca^<2+> sensitivity of vascular smooth muscles due to activation of the Rho kinase in retinal arterioles of SHR-SP were suggested. No apparent change was observed in shape or drug responsiveness in retinal venules of SHR-SP.