Blood Vessels (IMAGE) University Hospitals Cleveland Medical Center Caption In a new study published in PNAS, investigators at Harrington Discovery Institute and Case Western Reserve School of Medicine showed that a modified version of hemoglobin, termed S-nitrosohemoglobin, senses areas with insufficient oxygen, and then restores blood flow for oxygenation. Credit Canva Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.