Figure 9. Lead decreases photoreceptor and synaptic terminal oxygen consumption (QO₂) that is partially blocked by Bcl-xL overexpression. A: The QO₂ in dark- and light-adapted whole retina, outer retina, and inner retina of adult control mice. Light decreased whole and outer retinal QO₂. To determine QO₂ in the outer (photoreceptors) and inner retina, the outer retina was pharmacologically isolated from the inner retina using 2-amino-4-phosphonobutyric acid (APB), 6-cyano-7-nitroqunioxaline-2,3-dione (CNQX) or 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo-quinoxaline (DNQX), and D(-)-2-amino-5-phosphovalerate (APV) as described under Methods. B: Outer retinal QO₂ in dark- and light-adapted control, Lead, Bcl-xL and Bcl-xL/Lead adult retinas. Lead decreased dark- and light-adapted outer retinal QO₂, which were partially recovered in the Bcl-xL mice. C: Photoreceptor synaptic terminal QO₂ in control dark-adapted retinas and retinas stimulated with half-saturating and rod-saturating light. Photoreceptor synaptic terminal QO₂ was determined by adding CoCl₂, nifedipine, or both to the outer retinal pharmacological buffer as described under Methods. D: Dark-adapted photoreceptor synaptic terminal QO₂ in control, Lead, Bcl-xL, and Bcl-xL/Lead adult retinas. Lead decreased dark-adapted photoreceptor synaptic terminal QO₂ that was partially prevented in the Bcl-xL mice. Values represent mean±SEM measurements from four to seven different mice from different litters per treatment. Values sharing the same superscript differed from each other at p<0.05.