Which has a higher concentration of Vitamin C (ascorbate), aqueous humor or blood plasma?

The aqueous humor has a higher concentration of Vitamin C (ascorbate) compared to blood plasma. This is primarily due to the role of Vitamin C in the eye, where it serves several important functions, including acting as an antioxidant that helps protect the lens and retina from oxidative stress.

Vitamin C is transported into the aqueous humor from the blood, and its concentration is maintained at elevated levels in the eye to support these protective functions. The production and secretion of aqueous humor in the eye is facilitated by the ciliary body, which selectively takes up ascorbate from the plasma and actively secretes it into the aqueous humor.

The higher concentration of Vitamin C in the aqueous humor, compared to blood plasma, highlights the specialized metabolic needs of the eye in maintaining its health and function. This ascorbate also contributes to the refractive index of the aqueous humor and helps maintain the transparency of ocular tissues. Thus, the unique environment of the eye necessitates a greater concentration of this vital nutrient to ensure proper visual function and protect against damage from environmental factors.