Multi-phase expiratory inhibition of phrenic motoneurons in the decerebrate cat.
We studied the membrane potential changes of 11 phrenic motoneurons (PMs), located in the C5 portion of the cervical spinal cord, in decerebrate, paralyzed and artificially ventilated cats. Intracellular chloride iontophoresis into PMs could reverse the waves of inhibitory postsynaptic potentials (IPSPs) causing membrane hyperpolarization during expiration. In all PMs, we revealed, in addition to the previously described late expiratory augmenting wave of IPSPs, an early expiratory decrementing wave of IPSPs. Moreover, in three PMs, recorded in two cats exhibiting slow respiratory rhythms, an additional wave of IPSPs was interposed between the early and late ones. The possible origins and roles of these three different waves of inhibition are discussed.
Milano
S
S
Département de Physiologie et Neurophysiologie, CNRS URA 205, Faculté des Sciences et Techniques Saint Jérôme, Marseille, France.
Miller
A D
AD
Grélot
L
L
D000818:Animals; D002415:Cats; D002712:Chlorides / Q000494:pharmacology; D003655:Decerebrate State; D005260:Female; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D012119:Respiration / Q000502:physiology*; D013569:Synapses / Q000502:physiology
D002712:Chlorides; D011189:Potassium Chloride