The Effects of Dopamine on the Ventilatory Response to Sustained Hypoxia in Humans
The ventilatory response to acutely imposed sustained isocapnic hypoxia is biphasic(5). In humans, ventilation increases immediately in the first 3–5 minutes of hypoxia (hypoxic ventilatory stimulation, HVS), then gradually declines over the next 15–20 minutes to a value intermediate between the normoxic and the peak hypoxic ventilation(5). The initial hyperventilatory response is due to increased peripheral chemoreceptor output; however the mechanisms of the subsequent hypoxic ventilatory decline (HVD) are not well elucidated. In animals, the peripheral chemoreceptor discharge does not adapt during sustained hypoxia but the phrenic nerve efferent discharge does decrease(18) and hypoxia causes ventilatory depression when the carotid sinus nerve is cut(1). These findings suggest a central origin for the ventilatory decline. Increases in inhibitory central neuromodulators, such as GABA(17) and adenosine(4), and the hypoxia-induced increase in cerebral blood flow washing out acid metabolites(21) have been proposed as possible mechanisms for the ventilatory decline.
KeywordsCarotid Body Ventilatory Response Dopamine Infusion Hypoxic Ventilatory Response Carotid Sinus Nerve
Unable to display preview. Download preview PDF.
- 10.S. Kagawa, M.J. Stafford, T.B. Waggener, and J.W. Severinghaus, No effect of naloxone on hypoxia-induced ventilatory depression in adults, J. Appl. Physiol. 52:1031–1034 (1982).Google Scholar
- 21.R.B. Weiskopf, and R.A. Gabel, Depression of ventilation during hypoxia in man, J. Appl. Physiol. 39:911–915 (1975).Google Scholar