The Hering-Breuer reflexes in the bronchial asthma attack.

The correlation between pulmonary stretch receptor activity and inspiration-expiration duration quotient as well as respiratory frequency (Hering-Breuer reflexes) has been established before and during an asthma attack in the guinea-pig. The Hering-Breuer reflexes subserving the self-regulation of breathing during uninfluenced spontaneous breathing no longer prevail after induction of a bronchial asthma attack. Increased stretch receptor activity following increased lung volume does not lead to inhibition of inspiratory activity (lung inflation reflex), but to an enhancement of the asthmatic tachypnoea. The latter is assumed to result from the expiratory self-compression of the lungs (lung deflation reflex). The enhancement of the deflation reflex by increasing lung volume during the asthma attack is discussed with regard to the uneven ventilation and the conditions in lung mechanics underlying the excitation of the lung deflation or collapse endings.