[The effect of nicardipine on ischemic injury of rabbit retina].

The effect of nicardipine (NC), a calcium channel blocker, on retinal ischemia was investigated by electroretinogram (ERG). After 0.1 ml of 0.001% (group A), 0.01% (group B) or 0.1% (group C) solution of NC or normal saline (control group) was injected into the vitreous body of pigmented rabbits, ischemia was induced by increasing intraocular pressure (IOP) to 140 mm Hg for 60 min by injecting saline into the anterior chamber (n = 4 in each group), then re-perfusion was induced by decreasing the IOP. ERGs (a-, b-, and c-waves) were recorded before the ischemia and immediately, 1, 2, 3, 4, and 24 hours after the re-perfusion. The recovery rate of the ERG b-wave amplitude at 4 hours in groups A, B, C, and the control group was 64.2 +/- 5.4 (mean +/- standard deviation), 104 +/- 16.1, 71.9 +/- 9.1, and 48.1 +/- 6.8% of preischemic amplitudes, respectively. The recovery rate of group B at 4 hours was significantly higher in comparison to groups A and C (p < 0.05) and to the control group (p < 0.01). The ERG c-wave in the control group was replaced by a negative wave (PIII) after ischemia for 24 hours, while the c-wave appeared in three eyes out of seven in group B. The results suggest that NC can protect the retina including the retinal pigment epithelium against ischemia.