Interrelation between lung volume, arterial CO2 tension, and respiratory activity

Abstract

In anesthetized cats with open thorax the activity of the respiratory muscles (diaphragm and abdominal muscles) is studied as a function of lung volume and arterial CO2 tension. It is shown that the sensitivity of the inspiratory muscles to a given change in lung volume (V) (Hering-Breuer reflex) varies with the arterial pCO2 level, and conversely, that the CO2 sensitivity of the inspiratory motor system is dependent upon the volume of the lungs. The relations are fairly linear and can be expressed by the equation: M — M0 = K (pa CO2 — p0) (V0 — V), in which M represents inspiratory motor activity and M0, p0, and V0 and K are constants. The activity of the expiratory muscles is not dependent on CO2. regulation of respiration; Hering-Breuer reflex; electromyography of respiratory muscles Submitted on September 24, 1964