Systemic Hypertension Effects on the Ciliary Body and Iris. An Immunofluorescence Study with Aquaporin 1, Aquaporin 4, and Na+, K+ ATPase in Hypertensive Rats

Abstract

Aquaporin 1 (AQP1) and aquaporin 4 (AQP4) have been identified in the eye as playing an essential role in the formation of the aqueous humor along with the Na+/K+ ATPase pump. Different authors have described the relationship between blood pressure, aqueous humor production, and intraocular pressure with different conclusions, with some authors supporting a positive correlation between blood pressure and intraocular pressure while others disagree. The aim of this work was to study the effect of high blood pressure on the proteins involved in the production of aqueous humor in the ciliary body (CB) and iris. For this purpose, we used the eyes of spontaneously hypertensive rats (SHR) and their control Wistar-Kyoto rats (WKY). Immunofluorescence was performed in different eye structures to analyze the effects of hypertension in the expression of AQP1, AQP4, and the Na+/K+ ATPase α1 and α2 subunits. The results showed an increase in AQP1 and Na+/K+ ATPase α1 and a decrease in AQP4 and Na+/K+ ATPase α2 in the CB of SHR, while an increase in AQP4 and no significant differences in AQP1 were found in the iris. Therefore, systemic hypertension produced changes in the proteins implicated in the movement of water in the CB and iris that could influence the production rate of aqueous humor, which would be affected depending on the duration of systemic hypertension.

Association of Exercise Intensity with the Prevalence of Glaucoma and Intraocular Pressure in Men: A Study Based on the Korea National Health and Nutrition Examination Survey

“…Several studies have reported that exercise transiently lowers IOP [ 9 , 10 , 12 ], which is likely to be caused by the type of activity such as strain type, aerobic exercise, intensity, and frequency. However, elevated blood pressure after exercise may contribute to increased IOP due to the production of aqueous humour in the ciliary body and iris [ 31 ]. In our study, the IOPmax was highest in the vigorous intensity exercise group without a linear trend pattern.…”

Ocular Hypotonia and Transient Decrease of Vision as a Consequence of Exposure to a Common Toad Poison

“…The α1 subunit is present on the basolateral surface of the pigmented epithelium, while the α2 subunit is located in the nonpigmented epithelium on the side facing the aqueous humor [17]. Some studies have suggested that the Na + /K + ATPase α1 subunit might control overall sodium secretion to the aqueous humor, while the α2 may be responsible for the entry of sodium to the ciliary epithelium bilayer across the basolateral surface of the pigmented epithelium [18][19][20]. Inhibition of Na + /K + -ATPase in these tissues caused by exposure to bufadienolides was the most obvious reason for corneal dysfunction that caused a transient decrease of vision, and also for a hypotonia as a result of ciliary body dysfunction and disturbed control of aqueous humor production.…”

Altered Expression of AQP1 and AQP4 in Brain Barriers and Cerebrospinal Fluid May Affect Cerebral Water Balance during Chronic Hypertension

“…The brains were cut into four serial coronal sections. As previously described, the coronal sections were prepared for immunofluorescence and immunohistochemistry [ 59 , 60 ]. All sections were incubated overnight at 4 °C with the primary antibodies (Abnova, Taipei, China): rabbit anti-AQP4 (pab20767, 1:2000) and rabbit polyclonal anti-AQP1 (pab28892, 1:1000).…”