Aquaporin-1 and transendothelial water transport: Possible role in early atherosclerosis?

Macromolecular transport across the vessel wall, apparently the earliest pre-atherosclerotic event, is known to occur due to advection by transmural pressure driven water transport, characterized by the hydraulic conductivity (Lp). Our group´s discovery of the presence of aquaporin-1 (AQP) in aortic endothelial cells suggests a new possibility of water transport across the endothelial cell (EC), alongside the generally accepted paracellular route. In this paper, we propose a new theory to explain the experimentally observed pressure-dependent Lp lowering effect of AQP-blocking in whole rat aortas ex vivo. Our results suggest that AQP contributes about 30% to the phenomenological endothelial Lp at low transmural pressures. Controlling the Lp, via AQP expression, might serve as a future therapeutic target to inhibit early pre-atherosclerotic events.