Age-Related Changes in Water Transport by Corneal Endothelial Cells in Rats

Abstract

Senescence-associated alterations in the structure and function of the cornea make it more sensitive to such external agents as surgery, traumas, and disease, resulting in edema and vision impairment that can be corrected only by cornea transplantation. The role of aquaporins for cornea endothelium functioning, as well as age-related changes in their activity, is not entirely understood. We have studied age-related changes in the water permeability (P_f) of corneal endothelium plasma membranes and the mRNA expression levels of aquaporins aqp1 and aqp3 genes in Wistar and senescence-accelerated OXYS rats. At the age of 3 to 18 months, P_f increased in Wistar rats and decreased in OXYS rats, becoming two times lower than in the Wistar line. The expression of AQP1 mRNA (studied by real-time PCR) in the endothelium was the same in Wistar and OXYS rats at the age of 3 months. By the age of 18 months, it increased only in Wistar rats and became two times higher than in OXYS rats. The expression of aqp3 mRNA in the endothelium of 3-month-old OXYS rats was half that of Wistar rats and did not change with age, while it decreased in Wistar rats and at 18 months was four times lower than at 3 months. We propose that the increased water permeability of endothelial cells in Wistar rats is adaptive and compensates for the decrease in endothelial cell density with age, while the accelerated aging of OXYS rats eliminates this compensation.