Figure 2.

Resting intracellular Ca²⁺ levels are elevated significantly in rod cells from diabetic mice. A: Illustration of the measurement protocol. The inset shows a section of retina from a control mouse labeled with Fura2 and excited by 380 nm light. In this example, measurements were made from regions of interest positioned on 10 rod somas (circles). After measuring basal Ca²⁺ levels for 2 minutes, ionomycin (10 mmol/L) was applied with a Ca²⁺-free solution to measure the minimum 340/380 ratio (Rmin). Ca²⁺ was then elevated to approximately 1.2 mmol/L by applying Ames' medium in the presence of ionomycin to measure Rmax. B: Average basal Ca²⁺ levels were measured. The individual data points represent average measurements made from 2 to 10 rods in each eye [n = 21 control eyes (12 mice), 15 diabetic eyes (10 mice)]. The two samples showed a statistically significant difference. Data are expressed as means with 95% CIs. n = 21 control eyes (from 12 mice) and 15 diabetic eyes (from 10 mice) (B). ∗∗P ≤ 0.01. ONL, outer nuclear layer.