Optogenetic intervention to the vascular endothelium.

Endothelium lining the interior of cardiovascular system and most visceral organs plays an important role in vascular function. Its dysfunction occurs in some of the most challenging diseases. An important function of the endothelium is to release vasoactive substances that act on the smooth muscle to change vascular tones. Substance secretion from endocrine cells relies on membrane potentials and firing activity, while it is unclear whether the membrane potential regulates substance release from the ECs. Understanding of this requires selective intervention to membrane potentials of the endothelial cells in situ. Here we show a novel intervention to endothelial cells using the optogenetic approach. A strain of transgenic mice was developed with the Cre-loxP recombination system. These transgenic mice expressed channelrhodopsin (ChR) in endothelial cells driven by the vascular endothelial cadherin or cdh5 promoter. Linked in a tandem with YFP, the ChR expression was detected by YFP fluorescence in various endothelium-lining tissues and organs. The YFP fluorescence was observed in the lumen of blood vessels and pericardium, but not in tissues beneath the endothelium lining. Optostimulation of dissociated endothelial cells evoked inward currents and depolarization. In the isolated and perfused heart, surprisingly, optostimulation of endothelial cells produced fast, robust, reproducible and long-lasting vasoconstriction that was not blocked by either ET-1A or TXA2 receptor antagonist. Similar optical vasoconstriction was found in the isolated and perfused kidney. These results indicate that the optogenetics is an effective intervention to vascular endothelium where optostimulation produces vasoconstriction.