Nuclear microprobe analysis of chlorine distribution in the blue-light-exposed rat retina

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 1995-09, Vol.104 (1), p.306-310
• Main Authors: Chen, Enping, Pallon, Jan, Forslind, Bo
• Format: Article
• Language: English
• Subjects: Medicin och hälsovetenskap
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/0168-583X(95)00419-X

Blue-light exposure is a possible environment factor which causes senile macular degeneration, a prominent cause of visual impairment in elderly. Blue-light exposure causes inner segment edema and photoreceptor degeneration, probably by inhibiting the sodium-potassium pump on the inner segment membrane. Disturbance of the pump function may cause chlorine and sodium redistribution in the inner and outer segments, and edema in the inner segment. In the present study, 11 eyes from 11 Sprague-Dawley rats were used. Six rats were exposed to blue light (404 nm) at a retinal dose of 380 kJ/m 2, five were control. Chlorine and sulphur distribution were measured with the Lund Nuclear Microprobe (beam size: 12 × 12 μm, proton energy: 2.55 MeV, beam density at the target: 10–20 pA/μm 2). The chlorine concentration was calculated using sulphur as reference. The secondary characteristic X-rays were measured with a Kevex Si(Li) detector. The mean chlorine concentration was 0.82 mg/mg sulphur in the control inner segment layer. It was 1.83 and 2.00 mg/mg sulphur, 1 and 12 h after exposure, respectively. The mean chlorine concentration was 2.55 mg/mg sulphur in the control outer segment layer. It was 1.17 and 1.21 mg/mg sulphur, 1 and 12 h after exposure, respectively. The sodium signal is severely attenuated by the detector window, and the sodium distribution is assumed to be indicated by the chlorine distribution since these two elements follow each other closely in the cellular edema caused by metabolic inhibition. An accumulation of chlorine and sodium could be one of the reasons of the inner segment edema after blue-light exposure.