Effects of Chronic Continuous Exposure to Low Dose Carbon Monoxide on Hemoglobin Mass and Performance: 1480 Board #242 May 30 9:30 AM - 11:00 AM

Inhalation of carbon monoxide (CO) blocks the oxygen binding sites of the hemoglobin molecule and may produce similar effects as exposure to altitude. While single CO-doses and short-term application which are used in medicine and science do not exert measurable effects on erythropoiesis and performance, no data exists about chronic administration. PURPOSE: To determine the effect of chronic low dose CO-application on hemoglobin mass and performance. METHODS: For three weeks, eleven male healthy and moderately trained subjects inhaled a CO-bolus five times the day to increase their HbCO concentration in blood by approx. 5%. Eleven matched subjects received a placebo. Hemoglobin mass (Hbmass), serum erythropoietin concentration [EPO], ferritin, and basic hematological parameters were determined before and weekly during and until three weeks after the CO-inhalation period. An incremental step test until exhaustion on a cycle ergometer was performed before, at the end and one week after the CO administration period. RESULTS: During and after the intervention period, there were significant interactions between time and groups for Hbmass (p<0.001), ferritin (p<0.05), [EPO] (p<0.001), percentage (%) and immature reticulocytes (IRF) (both p<0.05) A tendency for an interaction was found for max. power and VO2max (p=0.1). In the CO-group, Hbmass continuously increased from 919 ±69g to 962 ±78g in week 3, (p<0.001) and persisted for the following three weeks. Whole blood and plasma volume did not change. Reticulocytes (%) and IRF increased after one week (ret% from 1.21 ±0.31% to 1.40 ±0.29%, p<0.01; IRF from 5.1 ±1.7% to 7.0 ±2.7%, p<0.05). [EPO] tended to increase after one week (p=0.07) and was suppressed in the post period (p<0.01). Ferritin markedly decreased during the inhalation period (from 106 ±37ng/ml to 72 ±37 ng/ml, p<0.001). VO2max tended to increase from 4230 ±280 ml/min to 4350 ±350 ml/min (p<0.1) immediately after the inhalation period and showed a significant relationship to the change in Hbmass (y=2.9x + 29, r=0.55, p<0.05). In the placebo group no effect was observed. CONCLUSIONS: Chronic continuous exposure to low dose carbon monoxide increasing HbCO by ~5% significantly increased erythropoietic activity and showed a positive effect on performance.