Ultraviolet radiation effects on rat lens lactate dehydrogenase. An estimation of UVR penetration depth into the eye.

Stefan L�fgren, MD (a, b), Per G. S�derberg, MD, PhD (a), Ralph Michael, MMedSci, Dipl. Ing. (a)

(a) St. Erik�s Eye Hospital, Research Department, S-112 82 Stockholm, Sweden

(b) Department of Medical Biochemistry and Biophysics, Biophysics Section,

Karolinska Institutet, Stockholm, Sweden

E-mail: [email protected]

(Poster presented at the 1st Internet Conference on Photochemistry and Photobiology, 1997)

Introduction

Since a long time it has been known that experimental exposure to ultraviolet radiation (UVR) damages the lens and induces cataract. Epidemiological studies show a correlation between exposure to solar UVR-B (280-315 nm) and increased incidence of cataract (reviewed by Bergmanson & S�derberg 1995). One hypothesis for the experimental UVR-induced cataractogenesis is that shortage of energy inhibits the ion-pumps (S�derberg 1990). UVR decreases the lens glycolytic activity in vivo (L�fgren & S�derberg 1995) and decreases lactate dehydrogenase (LDH) activity in vitro (Chen et al. 1989). To further elucidate if the UVR inhibition of glycolysis in the lens in vivo (L�fgren & S�derberg 1995) could be caused by LDH inhibition, an optimised histochemical procedure for the determination of LDH in lens sections was employed (L�fgren & S�derberg, 1997).

The histochemical technique was also applied to obtain information on the penetration of UVR-300 nm into the lens. Transmittance studies on different species have shown that only a minor part of UVR-300 nm falling on the cornea reaches the anterior surface of the lens and of that, in practice all radiation is attenuated within the lens (Bachem 1956, Barker 1979, Boettner & Wolter 1962, Gorgels et al. 1992, Maher 1978).