Depression of Ventilation by Dopamine in Man: EVIDENCE FOR AN EFFECT ON THE CHEMORECEPTOR REFLEX

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Abstract

Dopamine is present in the carotid body and has been postulated to be an inhibitory neurotransmitter. The purpose of this study was to determine the effects of dopamine on ventilation in man and to examine its mechanism of action. Dopamine (0.5-10 μg/kg per min) was infused in eight normal men at different levels of arterial chemoreceptor activity, produced by varying the inspired Po2. During normoxia dopamine produced a small decrease in minute ventilation (V̇e) and an increase in arterial Pco2. When arterial chemoreceptors were stimulated by hypoxia, infusion of dopamine produced a marked initial depression of V̇e followed by a sustained although less pronounced decrease in V̇e. An increase in Paco2 and a decrease in Pao2 were also observed. When arterial chemoreceptor activity was suppressed by hyperoxia, infusion of dopamine did not affect ventilation. Subjects also breathed a hypercarbic, hyperoxic gas mixture. The hypercarbia produces hyperventilation by stimulating central chemoreceptors, whereas the hyperoxia suppresses peripheral chemoreceptors. Dopamine did not alter ventilation while the subjects were breathing this gas mixture.

Authors

Michael J. Welsh, Donald D. Heistad, Francois M. Abboud