Ventilatory depression during mild hypoxia in adult humans

1. Reversible hypoxic ventilatory depression during mild hypoxia without functional disorders in the higher CSN in adult humans are described. Its significance from the phylogenetic point of view is discussed. 2. Biphasic ventilatory depression which gradually develops during sustained hypoxia is currently receiving much attention. Its possible underlying mechanisms: adaptation of the peripheral chemoreceptor activity, short-term potentiation, lowered central chemoreceptor PCO by increased brain blood flow, increased synthesis or release in the neurotransmitters or neuromodulators such as adenosine, GABA, opioid, dopamine, and somatostatin, depression in neuronal and energy metabolism in the brain and localized acid secretion over the central chemosensitive area are enumerated and discussed. 3. The possible presence of ventilatory depression while breathing ambient air is mentioned and discussed with its phylogenetic background. © 1995, PHYSIOLOGICAL SOCIETY OF JAPAN. All rights reserved.