The apelin-APJ system is a relatively new discovery. It has generated interest in part due to
it's apparent ability to counteract the renin-angiotensin system, which is frequently
overactive in many cardiovascular disease.
Apelin has the ability to cause blood vessels to relax, increasing their diameter and hence
blood flow down the blood vessel. The researchers wish to investigate the hypothesis that an
infusion of apelin will reduce the effects of angiotensin II, which is know to reduce the
diameter of blood vessels.