HYPOXIA, SMOKING HISTORY, AND EXERCISE

Abstract

Six nonsmokers and 6 cigarette smokers, 22-34 yr old, performed bicycle work (53% sea level .ovrhdot.VO2 max) for 30 min in an altitude chamber under 4 conditions: SL, simulated sea level (PIO2 [inspired O2 tension] = 159 torr, PB [barometric pressure] = 523 torr) with 0.5% HbCO; SLCO, simulated sea level with 4.2% HbCO; A, altitude (PIO2 = 109 torr, PB = 523 torr) with 0.5% HbCO; and ACO, altitude with 4.2% HbCO. During work at altitude, heart rate (HR), minute ventilation and tidal volume increased and diastolic blood pressures decreased relative to SL. Cardiac output (.ovrhdot.Qc), stroke volume (SV) and arterial-mixed venous oxygen difference (a-.hivin.vO2) were similar in smokers and nonsmokers at SL, SLCO and A. At ACO, nonsmokers increased .ovrhdot.Qc and SV and decreased a-.hivin.vO2, but these were not influenced in the smokers. Smokers showed a graded increase in HR when exposed to work in SLCO, A and ACO. Their lower finger temperatures during A and ACO suggested vasoconstriction in the extremities. Cigarette smokers may be partially adapted to hypoxia.