Intracellular recording from phrenic motoneurons receiving respiratory drive in vitro.

Stable, long-term (2-4 h) intracellular recordings were obtained from phrenic motoneurons receiving respiratory drive in an in vitro neonatal rat brainstem-spinal cord preparation. Several passive and active phrenic motoneuron properties in vitro, including resting membrane potential, inspiratory drive potentials, and threshold depolarization levels, are similar to those in the adult mammal in vivo. Manipulations of the extracellular fluid environment by the addition or washout of chemicals affecting motoneuronal activity and spinal synaptic transmission of respiratory drive did not affect the quality of the intracellular recordings. These results establish the feasibility of long-term intracellular recording from the in vitro brainstem-spinal cord preparation for studies of cellular and synaptic mechanisms underlying control of respiratory movements.