A gas molecule has been attached to protamine sulfate by a research team, creating a new nitric oxide generator that could potentially reduce bleeding complications during surgery. During open-heart procedures, physicians administer large doses of a blood-thinning drug called heparin to prevent clot formation. When given too much heparin, patients can develop complications from excessive bleeding. A common antidote is the compound protamine sulfate, which binds to heparin to reverse its effects.