Ignarro’s spectral analysis

Louis Ignarro reported that EDRF relaxed blood vessels. He also identified EDRF as a molecule by using spectral analysis of hemoglobin. When hemoglobin was exposed to EDRF, maximum absorbance moved to a new wave-length; and exposed to NO, exactly the same shift in absorbance occurred! EDRF was identical with NO. A new principle for signalling between human cells was discovered.

Spectrophotometry

 Hemoglobin (yellow) exposed to endothelial cells that were stimulated to produce EDRF (green)
 Hemoglobin (yellow) directly exposed to NO (green)

The shift of absorption curves is identical, hence EDRF is NO

To cite this section
MLA style: Ignarro’s spectral analysis. NobelPrize.org. Nobel Prize Outreach 2025. Fri. 5 Dec 2025. <https://www.nobelprize.org/prizes/medicine/1998/7539-ignarros-spectral-analysis/>

Nobel Prizes and laureates

Six prizes were awarded for achievements that have conferred the greatest benefit to humankind. The 14 laureates' work and discoveries range from quantum tunnelling to promoting democratic rights.

See them all presented here.

Illustration

Explore prizes and laureates

Look for popular awards and laureates in different fields, and discover the history of the Nobel Prize.