Electrophysiological consequences of leukotrienes applied on isolated rat retina

Scotopic vision is the result of a cascade of light-dependent biochemical events in rod outer segments (ROS) involving mainly a cGMP-modulation of sodium current. This modification of ionic currents induces changes of membrane potential which generates electroretinographic (ERG) waves. As (i) ERG disturbances are commonly recorded in hypoxic and inflammatory retinal diseases (ii) leukotrienes (LTs), a very potent mediators of inflammation, disturb ionic exchanges in several artificial or natural membrane systems, we undertook the investigation of the effects of LTs on ERG record in mammalian isolated retina. LTB4, LTC4 and LTD4, all induced a dose-dependent marked reduction of the b wave amplitude of ERG. This effect is correlated with a significant decrease in the survival time of the retina. The analysis of the modification of ERG indicates that LTs exhibit a real toxic effect since b wave is mainly affected while P III wave is unchanged. Comparatively with other nervous cells, this phenomenon may be attributed to an increase in Na+ permeability of ROS. It is suggested that LTs may be involved in the development of inflammatory or ischemic retinal diseases.