[Endogenous content of the nitric oxide in the cell layers of the eye retina].

Nitric oxide is a universal molecule that regulates many different functions in an organism. In the eye retina nitric oxide plays both a regulatory role by modulation of the synaptic transmission between photoreceptors and bipolar cells and a toxic role in apoptosis induction in the outer nuclear layer and in the layer of ganglion cells. In this paper there has been made the first attempt to estimate the endogenous NO concentration in retina layers in vivo. The concentration of the nitric oxide was determined by two indepen- dent techniques: ESR spectrometry using spin trap for in vivo determination and NO-sensitive microelectrode for in situ determination in the survival isolated frog retina. The distinct NO con- centration was detected only in the ganglion cells layer (~0.25 μM) and in the inner segments layer of the photoreceptors (~0.6 μM). The activity and the kinetic characteristic of the NO-synthase localized in the same layers were also determined. Key words: retina cells layers, nitric oxide, ESR, NO-sensitive microelectrodes.