Running Head: A Novel Ankyrin Protein Required for N2-Fixing Symbiosis

A method and device for perfusing an organ system is provided. The device may be further described as a catheter or cannula with an expandable flow control member positioned of the distal portion of the catheter shaft. The flow control member has a porous portion, and at least one impermeable portion, which prevent fluid from flowing out the ends of the flow control member. The flow control member is further characterized as having an interior chamber that is in fluid communication with a perfusion lumen that extends along the length of the catheter shaft and is in fluid communication with an external perfusion pump. The perfusion lumen is configured for providing flow to the interior of the flow control member, to create radial expansion thereof and to provide adequate flow to the arch vessels through said porous portion to sustain the metabolic demands of the brain.