Hemoglobin and Nitric Oxide (NO)

Continuing down the chain of associations, I tried searching on "hemoglobin and nitric oxide" and it turns out that hemoglobin, which is normally locked up inside the red blood cells aka erythrocites, can cause mischief when it escapes into the blood plasma. Once it is loose, free hemoglobin "scavenges" nitric oxide (NO), which is a very important regulatory chemical.  This reduces the available NO, messes with the regulation, and can lead to "vasoconstriction, decreased blood flow, platelet activation, increased endothelin-1 expression (ET-1), and end-organ injury...." 

As noted in a previous post, vasoconstriction is what reduces the blood flow to your toes in the cold. Platelet activation as used in this technical article, can be loosely translated as clotting. So maybe the Massachusetts investigators are on to something, but perhaps not for the reasons the reporter suggested.  It looks more likely that inhaling NO could be helpful by restoring this chemical to its normal level by replacing what was deactivated by the renegade hemoglobin.  It is not spelled out but it seems clear the authors of this technical article use the word scavenge to mean that some sort of chemical reaction happens between the free hemoglobin and NO that takes the NO out of circulation.  

The biochemistry of nitric oxide, nitrite, and hemoglobin, role in blood flow regulation