Metabolic control of respiratory neuronal activity and the accompanying changey-expiratory neurons.
Expiratory-related neurons have been classified according to their phase relation within the respiratory cycle, their response to lung distension and collapse (alpha- and beta-type), and to hyperventilation (tonic firing denoted by "+", cessation of activity by "-"). The dorsal surface of the medulla oblongata was superfused with a metabolite-containing CSF solution and the activity of expiratory (E) and inspiratory-expiratory (IE) neurons was extracellulary recorded. The neuronal sub-types established by their functional behaviour could equally be distinguished by their differential response to one or several metabolites. In contrast to inspiratory (I) neurons, Ealpha- Ebeta-, Ebeta- and IEbeta- neurons are inhibited by 3.5 mM AMP, but are activated by 10 mM citrate (with the exception of Ebeta+ units). Furthermore I cells are activated by ATP, while Ealpha and Ebeta units become inhibited. Vagotomy in some instances affected the response of some IEbeta units. An increase in spike density of IEbeta+ and Ealpha- cells is paralleled by a reduction of both the respiratory rate and the tidal volume, while a lower spike density in IEbeta+, IEbeta- and Ealpha- units is accompanied by increases in respiratory rate and tidal volume. In the case of Ebeta+ and Ebeta- cells lower activity is associated with an increased tidal volume. No metabolite-induced changes could be obtained with cardiovascular or unspecific reticular neurons.
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001683:Biological Clocks; D002951:Citrates / Q000494:pharmacology; D004594:Electrophysiology; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D006985:Hyperventilation; D009474:Neurons / Q000201:enzymology / Q000502:physiology*; D010732:Phosphofructokinase-1 / Q000378:metabolism; D011817:Rabbits; D012119:Respiration; D012125:Respiratory Center / Q000201:enzymology / Q000502:physiology*; D013238:Stereotaxic Techniques; D013990:Tidal Volume
D002951:Citrates; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1; D006597:Fructose-Bisphosphatase