Losartan inhibits the increased leukocyte entrapment usually seen in the retinal microcirculation of diabetic rats, according to results of a study in Japan. The finding implies that the potent AT1 angiotensin II receptor antagonist may inhibit the development of diabetic retinopathy, the researchers maintain.
It is theorized that increased retinal leukocyte entrapment in diabetes may be associated with vascular nonperfusion and vascular leaking, thus leading to diabetic retinopathy, explain Dr. Fumihiko Mori and associates of the Asahikawa Medical College.
Dr. Mori’s group induced diabetes in 12 rats by injecting streptozocin. Six were given water supplemented with losartan potassium so that they ingested approximately 5 mg/kg/day for 4 weeks. The remaining six animals, as well as six uninjected rats, received no treatment.
As noted in the British Journal of Ophthalmology for October, acridine orange, a fluorescent nuclear dye, was administered to the animals at 4 weeks. The researchers then examined the fundus of the left eye in each rat using confocal scanning laser ophthalmoscopy.
The number of trapped leukocytes averaged 6.1/mm² in the untreated diabetic rats, significantly more than the 3.1/mm² in the losartan-treated animals and the 2.8 cells/mm² in the control rats, the report indicates.
This finding is in accord with previous reports of a protective effect of losartan on a model of laser-induced choroidal neovascularization in rats, Dr. Mori’s group notes. They also point out that losartan has shown efficacy in treating diabetic nephropathy. Br J Ophthalmol 2002;86:1172-1174.