Furchgott's Experiment with Acetylcholine

Furchgott's experiment demonstrated that acetylcholine, a chemical messenger, causes blood vessels to relax and widen, but only if the lining of the vessels (endothelium) is intact. He observed that in dissected vessels with this lining, acetylcholine increased blood flow by triggering the production of nitric oxide, a molecule that relaxes the muscle in the vessel walls. When the endothelium was removed, acetylcholine no longer caused relaxation, highlighting its role in signaling through nitric oxide. This experiment revealed how blood vessels naturally regulate their diameter, a crucial process in controlling blood pressure and flow.