Long-term intracellular recordings of respiratory neuronal activities in situ during eupnea, gasping and blockade of synaptic transmission.
For a definitive evaluation of the hypothesis that different neurophysiological mechanisms underlie the neurogenesis of eupnea and gasping, long-term continuous intracellular recordings of respiratory neuronal activities during both respiratory patterns are required. Such recordings in vivo are technically difficult, especially in small mammals, due to mechanical instability of the brainstem and cardiovascular depression that accompany hypoxia-induced gasping. Respiratory-related rhythmic activities of in vitro preparations are confounded by the lack of a clear correspondence with both eupnea and gasping. Here, we describe new methodologies and report on whole cell patch clamp recordings from the ventrolateral medulla and the hypoglossal motor nucleus in situ during multiple bouts of hypoxia-induced gasping. The longevity of recordings (range 20--35 min) also allowed subsequent analysis of neuronal behaviour after blockade of inhibitory and excitatory synaptic activities. We conclude that whole cell patch clamp recordings in the in situ preparation will allow an analysis of both synaptic and ionic conductances of respiratory neurons during defined eupnea and gasping, providing an additional approach to in vitro preparations.
Paton
Julian F R
JF
Department of Physiology, School of Medical Science, University of Bristol, Bristol, England BS8 1TD, UK. Julian.F.R.Paton@Bristol.ac.uk
St-John
Walter M
WM
D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D004347:Drug Interactions; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists; D018684:Glycine Agents / Q000494:pharmacology; D007040:Hypoventilation / Q000503:physiopathology*; D007736:Kynurenic Acid / Q000494:pharmacology; D008526:Medulla Oblongata / Q000166:cytology* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D012119:Respiration; D013331:Strychnine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018684:Glycine Agents; D010879:Piperazines; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid; D007736:Kynurenic Acid; D013331:Strychnine; D001640:Bicuculline