[Changes in the activity of phrenic motor neurons in response to reduced compliance of the abdominal wall (apropos of the significance of the excitatory intercostal-phrenic reflex)]

Abstract

A pressure on the abdomen by pneumatic cuff was performed in 13 decerebrated vagotomized cats for enhancing the excitatory intercostal-to-phrenic reflex. "Moving averages" of the electrograms of the phrenic nerve and oblique abdominal muscles, as well as abdominal cavity pressure were recorded. In these conditions the changes of the phrenic activity were weak and inconsistent. Significant changes of the peak amplitude of phrenic ENG were absent. In the majority of the experiments diminutions of the respiratory cycles, inspiratory and expiratory durations (up to 6%), as well as enhancing of the rate of rise of phrenic activity (up to 5-7%) took place. The latter can be a manifestation of the intercostal-to-phrenic reflex. This reflex in breathing may have but a weak influence on the phrenic motoneurons excitation.