Dopamine withdrawal causes chemoreflex-related increase in minute ventilation

Abstract

Background: Dopamine decreases activity of peripheral chemoreceptors, however the effects of low-dopamine infusion on minute ventilation during normoxia has not been comprehensively assessed. Methods: We performed double-blinded, crossover, randomized and placebo-controlled study on 11 healthy male volunteers (median age 26 years). In all subjects continuous measurement of minute ventilation was performed using one-way respiratory circuit during low-dose dopamine (2 mcg/kg/min) and saline infusions. Transient hypoxic method was used to assess peripheral chemosensitivity during same dopamine and saline infusion. Results: Low-dose dopamine infusion significantly reduced peripheral chemosensitivity (0.16 l/min/SpO2, interquartile range [IQR] 0.02-0.24 vs 0.40 l/min/SpO2, IQR 0.26-1.49, dopamine vs saline infusions, respectively, p=0.003). Initiation of neither dopamine nor saline infusions significantly change minute ventilation once compared to baseline recording (for dopamine: 9.34 l/min, IQR 8.38-11,66 vs 9.91 l/min, IQR 7.92-11.49, p=ns; for saline: 10.20 l/min, IQR 8.77-11.38 vs 10.93 l/min, IQR 8.57-11.54, p=0.55). However, termination of dopamine infusion led to significant increase in minute ventilation vs period on dopamine (11.69 l/min, IQR 9.56-12.86 vs 9.08 l/min, IQR 8.57-12.15, p=0.016) which was not observed after saline infusion withdrawal (10.77 l/min, IQR 9.36-11.87 vs. 10.52 l/min, IQR 9.11-12.64, p=0.53). Increase in minute ventilation induced by dopamine withdrawal correlated with peripheral chemosensitivity measured during saline infusion (rho=0.61, p<0.05). Conclusion: Low-dose dopamine infusion has asymmetrical effect on minute ventilation in healthy men. Its initiation results in no change, while termination – in marked increase in minute ventilation. Magnitude of respiratory response to dopamine withdrawal is related to peripheral chemosensitivity.