Identification and classification of respiratory pacemaker neurons in the medial region of nucleus retrofacialis in neonatal rats / 生理学报

ABSTRACT

The aim of the present study is to supply direct experimental proof that the medial region of nucleus retrofacialis (mNRF) is the site generating basic rhythm of respiration. Medullary slices of neonatal Sprague-Dawley rats, including hypoglossal nerve root and mNRF, were made according to Suzue's method. Simultaneous recordings of the respiratory rhythmic discharge activity (RRDA) in hypoglossal nerve root with suction electrode and the respiratory neuronal discharge in the mNRF with whole cell patch clamp were performed on the brainstem slice in vitro. Not only the electrophysiological characteristics of pacemaker and non-pacemaker neurons, but the cadmium-sensitivity of pacemaker neurons was observed. The nature of the discharge in the respiratory pacemaker neurons in mNRF was spontaneous, rhythmical and voltage-dependent burst behavior, generating an ectopic burst in response to a depolarizing or hyperpolarizing current. There were no significant differences in capacitance of membrane (C(m)), input resistance of membrane (R(m)) and leak inward current (I(leak)) between the pacemaker neurons and the non-pacemaker ones. Moreover, most pacemaker neurons in the mNRF were Cd(2+)-insensitive. In conclusion, these results support the idea that the mNRF is the site generating basic respiratory rhythm.