Abstract
Purpose: :
To evaluate the reflection coefficient of bovine Bruch’s membrane (BrM) and choroid to low-density lipoprotein.
Methods: :
A 2x2 cm tissue square of BrM and choroid from the non-tapetal region was gently separated from three bovine eyes within 8 hours postmortem. The tissue was then placed into an Ussing chamber in a perfusion system. The upstream compartments of the perfusion system were filled with Dulbecco's phosphate-buffered saline (DPBS) containing 0.01-mg/ml fluorescent 3,3'-dioctadecylindocarbocyanine low-density lipoprotein (DiI-LDL). The downstream compartments were filled with DPBS. After the tissue was perfused at a pressure of 10 mmHg for 18 to 24 hours, the concentrations of DiI-LDL in the upstream and downstream compartments were determined by measuring the fluorescence intensity emitted by DiI-LDLs. The reflection coefficient of BrM and choroid was then evaluated using Kedem-Katchalsky equation.
Results: :
Fluorescence emitted by DiI-LDLs was detected in the solution in downstream chamber and compartments after the perfusion, suggesting DiI-LDL could be perfused through bovine BrM and choroid. The reflection coefficient of BrM and choroid of three bovine eyes to DiI-LDL were found to be 0.62, 0.66, and 0.67.
Conclusions: :
Our result shows that low-density lipoproteins can be transported through BrM and choroid by a small flow. Large lipoprotein-like particles are known to accumulate in BrM of aging human eyes. The finding of the current study suggests it is possible that these particles "squeeze" through the small interfibril spacing of the basal lamina of BrM and accumulate in the tissue.
Keywords: Bruch's membrane • lipids • aging