Oxygen profiles and oxygen consumption in the isolated mouse retina

The retina has a large demand for oxygen, but there is only limited information on differences between oxygen utilization (QO₂) in the inner and outer retina, and limited data on mouse, which has become a prevalent animal model. This study utilized the isolated mouse retina, which allowed more detailed spatial analysis of QO₂ than other methods. Oxygen sensitive microelectrodes were used to obtain profiles of oxygen tension across the isolated mouse retina, and mathematical models of retinal oxygen diffusion with four and five layers were fitted to the data to obtain values for QO₂ of the outer retina (QOR) and inner retina (QIR). The boundaries between layers were free parameters in these models. The five-layer model resulted in lower error between the model and data, and agreed better with known anatomy. The three layers for the outer retina occupied half of the retina, as in prior work on rat, cat, and monkey, and the inner half of the retina could be divided into two layers, in which the one closer to the vitreous (layer 5) had much lower QO₂ than the more distal inner retina (layer 4). QIR in darkness was 3.9 ml O₂-100 g⁻¹-min⁻¹, similar to the value for intact cat retina, and did not change during light. QOR in darkness was 2.4 ml O₂-100 g⁻¹-min⁻¹, lower than previous values in cat and rat, possibly because of damage to photoreceptors during isolation. There was a tendency for QOR to be lower in light, but it was not significant in this preparation.