What is Isoflurane and the RAS? Isoflurane is a gas anesthetic that keeps patients asleep and pain-free during surgery by acting on the brain’s chemical messengers. It strengthens the calming effects of GABA-A receptors while blocking NMDA receptors, reducing the brain’s electrical activity and preventing pain signals. These actions slow communication between nerve cells, allowing the body to relax and remain unconscious. Researchers continue to investigate how these pathways may impact memory, inflammation, and brain health, particularly in older adults. The renin–angiotensin system, or RAS, is the body’s way of controlling blood pressure, fluid balance, and blood vessel tone. When blood pressure drops, the kidneys release a hormone called renin, which triggers the production of angiotensinogen, a precursor to angiotensin II. This chemical constricts blood vessels, helping to raise blood pressure back to normal. This system also works in the brain, where angiotensin II can influence b...