[Physiological and neuropharmacological aspects of the central respiratory mechanisms]

The present physiological and neuropharmacological views and the essentials of the experimental results on the anatomical localization, functional and neuronal organization of the central respiratory mechanisms, classically expressed as the respiratory centers, in the brain stem were reviewed and discussed. The brain stem neural mechanism for central regulation of breathing is regarded as a complex neuronal mechanism consisting of several functional subsystems subserving different functions. One of its functions is the generation of respiratory rhythm. The subsystem for respiratory rhythm-generating mechanisms is located in the medullary reticular formation outside the DRG and VRG regions, which are thought to be premotor neuron pools. Rhythmic activity originating in the medulla is dominant in terms of the spontaneity over other rhythmic activity in the pontine and spinal cord mechanisms. Evidences for heterogeneity of the functional properties of brain stem respiratory neurons have been demonstrated. Neuronal mechanisms involving respiratory neurons identified as members of the primary respiratory neuron population or neuronal networks consisting of different types of respiratory neurons located in the lateral region of the bulbar reticular formation may play important roles in the generation of respiratory rhythms. These aspects contribute to the understanding of the neurophysiological basis, providing important prerequisites for further neuropharmacological studies on neurotransmission within the neuronal network of the central respiratory mechanisms.