Purchase this article with an account.
R.A. Linsenmeier, G. Birol, S. Wang, E. Budzynski, N.D. Wangsa–Wirawan; Oxygen Distribution and Consumption in the Macaque Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5895.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
In order to provide information about retinal metabolism in primates, this study investigated oxygen distribution and consumption in the macaque retina.
PO2 depth profiles were recorded from retinas of intact, isoflurane/N2O anesthetized adult macaques (2 Rhesus and 4 Cynomolgus) using double–barreled oxygen microelectrodes. Arterial blood parameters were monitored and kept within normal limits. Profiles were obtained in dark adaptation and after adaptation to an illumination that was sufficient to at least saturate rod responses. The electroretinogram (ERG) was used to assess the position of the electrode in the retina. The three layer one–dimensional diffusion model previously used for cat retina was fitted to profiles to determine photoreceptor oxygen consumption per unit volume, Qav, or per unit area, Qav* (Qav* = Q2(L2–L1) where Q2 is consumption in the inner segments, and L1 and L2 are boundaries of the consuming layer).
In the parafovea, the PO2 at the choroid was high (48 ± 13 mm Hg), but it decreased to a minimum of 3.3 ± 1.9 mm Hg (n=6) around the photoreceptor inner segments in dark adaptation. The minimum PO2 was significantly higher, 12.6 ± 1.8 mm Hg (n=4), in light adaptation in the cynomolgus, but it did not increase in the rhesus. Choroidal PO2 was unchanged during light adaptation in all animals. Qav* was 8.2 ± 3.3 mL O2–µm/100 g–min (Qav = 3.6 ± 1.5 mL O2/100 g–min) under dark adapted conditions in parafovea. Qav* decreased to 74% ± 13% (n=6; p= 0.015) of the dark–adapted value in light adaptation. Oxygen consumption was strongly dependent on choroidal PO2 in both light (R2=0.92) and dark (R2=0.94). In dark adaptation, foveal Qav* was 58% ± 12% (n=2) of the parafoveal value, similar to the result obtained for one monkey in a previous study of primate retinal oxygenation (Ahmed et al., 1993).
Oxygen distribution and consumption of the parafoveal monkey retina are similar to these properties in the cat area centralis, but changes in photoreceptor QO2 during illumination are smaller in monkey. Foveal oxygen consumption is lower than that in the parafovea, suggesting that cones may use less oxygen than rods.
This PDF is available to Subscribers Only