Digoxin increases peripheral chemosensitivity and the ventilatory response to exercise in normal subjects

Area of Science:

• Physiology
• Exercise Physiology
• Cardiorespiratory Regulation

Background:

• Peripheral chemoreceptors play a crucial role in regulating ventilation during exercise, but their precise contribution is not fully understood.
• Digoxin has been previously suggested to augment chemoreflex sensitivity in humans.

Purpose of the Study:

• To investigate whether digoxin-induced enhancement of chemoreflex sensitivity increases the ventilatory response to exercise in healthy subjects.
• To assess the impact of digoxin on minute ventilation (VE) in relation to carbon dioxide production (VCO2) during exercise.

Main Methods:

• A randomized, cross-over, double-blind study involving 11 healthy young male subjects.
• Measurements included minute ventilation, end-tidal PCO2, oxygen saturation (SpO2), heart rate, and blood pressure during normoxia, hypoxia, and hypercapnia.
• Subjects underwent a maximum cardiopulmonary exercise test after intravenous infusion of digoxin or placebo.

Main Results:

• Digoxin increased systolic blood pressure during normoxia.
• During hypoxia, digoxin significantly increased minute ventilation (VE) for a given decrease in oxygen saturation (SpO2).
• Digoxin elevated the VE/VCO2 slope above the anaerobic threshold (30.4 to 32.8) but did not alter maximal oxygen uptake (VO2max).

Conclusions:

• Enhanced peripheral chemosensitivity via digoxin administration augments the ventilatory response to carbon dioxide production above the anaerobic threshold.
• Digoxin does not appear to affect maximal exercise capacity in healthy individuals.