Quantitative Recovery of ¹⁴C-labeled Carbon Monoxide (¹⁴CO) From Viable Heme-labeled Red Blood Cells in the Rat

Long-term recovery of ¹⁴C-labeled carbon monoxide (¹⁴CO) from labeled, transfused red blood cells (RBC) was studied in buffalo rats. Donor RBC (labeled with ¹⁴C-2-glycine) were transfused into host rats, and the ¹⁴CO formed from degradation of labeled hemoglobin heme was collected over the next 110+ days. The heme-equivalent ¹⁴CO recovery in 13 animals averaged 102.1 ± 2.1% (mean ± SE) of activity in hemoglobin heme of donor RBC. This confirms that heme of circulating RBC destroyed by random hemolysis and senescence is quantitatively converted to CO.