Skip to main content
. 2004 Jul 22;559(Pt 3):883–898. doi: 10.1113/jphysiol.2004.068619

Figure 5. Measurement of and PO2 profiles in regionally dissected bovine lenses.

Figure 5

A, Q̇O2 was measured immediately after dissection (open bars) or after a 4 h equilibration period (grey bars). Measurements were made at 37°C in solutions containing 21% oxygen. Cortical samples deteriorated over the 4 h equilibration period. Consequently, only an initial cortical measurement was possible. The relatively high Q̇O2 value of the isolated cortex suggests that much of the oxygen consumption of the intact tissue can be attributed to the outer fibre cell layers, though some of the initial consumption represents the redistribution of oxygen from the medium into the relatively hypoxic tissue. In contrast, epithelial oxygen consumption appears to represent only a minor component (approximately 3%) of the total oxygen consumption. The Q̇O2 values of equilibrated core samples are significantly lower than those measured immediately after dissection, again probably due to the initial redistribution of oxygen. B, bovine lenses were dissected to remove the DF cell layer. Isolated cores (•) were equilibrated with 21% oxygen. Data from intact lenses (taken from Fig. 1) are shown for comparison (○). Following the removal of the DF cell layer, PO2 is elevated throughout the remaining core sample. However, a steep gradient persists within the core, and even after prolonged incubation, the PO2 within the sample does not equal that in the bathing medium. Data represent mean ±s.d. for 5 independent measurements in each case. C, Q̇O2 was measured in intact (open bars) or homogenized (grey bars) lens cores in the presence or absence of various inhibitors. The Q̇O2 values were consistently higher in homogenized samples. Compared to control values, treatment with the PMOR inhibitors capsaicin and NADH had no significant effect on Q̇O2 in either intact or homogenized samples. However, treatment of homogenized lens cores with the metal chelator DETAPAC resulted in a significant inhibition of Q̇O2. Values that differ significantly (P < 0.05) from controls are indicated by an asterisk.