Ventilatory response to carbon monoxide during exercise in hypoxia and hypercapnia

Publication date: Available online 24 August 2017 Source:Respiratory Physiology & Neurobiology Author(s): George H. Crocker, Jenny Kwon, Philip H. Kass, James H. Jones We tested if the addition of CO to inspired gases with different inspired O2 and CO2 fractions (F IO2 and F ICO2) stimulates ventilation at rest or during submaximal exercise. We measured minute ventilation (V E) in goats breathing combinations of F IO2 ranging from 0.21 to 0.06 and F ICO2 from 0 to 0.05, both with and without inspired CO resulting in carboxyhemoglobin fractions (F HbCO) of 0.02 (no CO added), 0.15, or 0.45. We did this while they stood on a treadmill, walked at 1.4, or trotted at 2.5ms−1. Hypoxia, hypercapnia, and exercise, alone and in combination, increased ventilation compared to breathing air at rest. Both elevated F HbCO increased V E compared with ambient F HbCO during exercise (increases of 1.50 and 5.53mls−1 kg−1 for F HbCO 0.15 and 0.45, respectively; P =0.035), but not at rest (P =0.958), when the ventilatory effects of F IO2 and F ICO2 are factored out. Additionally, F HbCO 0.45 (but not 0.15) increased V E compared to F HbCO 0.02 for all F IO2 and F ICO2 when the ventilatory effects of exercise are factored out. Taken together, these data suggest that exercise intensity and F HbCO dose interact to stimulate ventilation during exercise.
Source: Respiratory Physiology and Neurobiology - Category: Respiratory Medicine Source Type: research