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Mechanism underlying the changes in respiratory movement in respiratory distress syndrome caused by oi etc acid in rabbits

Ni Hui, Jin Longxuan, Tend Yiling

Department of Physiology, Nanjing Medical College. Jiangsu, China

Abstract

Respiratory distress syndrome (RDS) produced experimentally in rabbits by intravenous injection of oleic acid was characterized by phasic changes in pulmonary ventilation, i.e., an initial hyperventilatory phase, a delayed hyperventilatory phase and finally followed by a hypoventilatory phase. The amplitude of respiratory movement shown by intrathoracic pressure curves underwent a consistent and gradual increase with concomittent reduction of tidal volume. Marked drop in O_(2) absorption rate and CO_(2) output rate occurred only during the hypoventilatory phase. In accordance with the shift of respiratory pattern, respiratory alkalosis and acidosis shown by blood gas analysis were observed in the hyperventilatory and hypoventilatory phases respectively. Arterial PO_(2) was maintained above 80 mmHg in the initial 20 minutes after injection and declined subsequently. The initial hyperventilatory phase disappeared after bilateral vagotomy while the late hyperventilatory phase and hypoventilatory phase still persisted. In contrast to this, after bilateral sinus denervation, the initial hyperventilatory response to injection of oleic acid was still present, while the late hyperventilatory phase disappeared. Therefore, it is assumed that the tachypnea and the early phase of hyperventilation following injection of oleic acid are mainly initiated by way of the vagus nerve, while the late hyperventilatory phenomenon is due to anoxemia involving peripheral chemoreceptors.

Key words: Respiratory distress syndrome;Oleic acid;Ventilation;O_(2) absorption rate;CO_(2) output rate;Vagal nerve;Sinus nerve;Anoaemia

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Citing This Article：

Ni Hui, Jin Longxuan, Tend Yiling. Mechanism underlying the changes in respiratory movement in respiratory distress syndrome caused by oi etc acid in rabbits. Acta Physiol Sin 1985; 37 (3): (in Chinese with English abstract).