P1334

         Bull Eur Physiopathol Respir 1983 Jan-Feb;19(1):23-6

        Effect of vagal cooling on lung functional residual capacity in rats

        with pneumonia.

        Vizek M, Frydrychova M, Houstek S, Palecek F.

        We examined the effect of cold vagal block on the functional residual

        lung capacity (FRC) in control rats and in rats with experimental

        pneumonia induced by intratracheal administration of the herbicide

        paraquat. The measurements were performed in a body plethysmograph in

        anaesthetized and intubated rats. Rats with pneumonia had tachypnoea and

        increased minute ventilation. Their FRC was 3.6  0.7 ml in comparison

        with 2.5  0.6 ml in controls (mean  SD). Cooling the cervical

        vagi, so that the Hering-Breuer inflation reflex was abolished

        (approximately 8 degrees C), resulted in a marked decrease of the rate

        of breathing and an increase of tidal volume in both groups of animals.

        The value of FRC did not change during vagal cooling (3.7  0.9 ml in

        rats with pneumonia, 2.8  0.8 ml in controls). In rats with model

        pneumonia, bilateral cervical vagotomy was followed by a normalization

        of the FRC (2.3  0.7 ml). In control animals, the FRC did not change

        after vagotomy (2.5  0.6 ml). We conclude that increased FRC in rats

        with paraquat pneumonia depends on intact conduction through thin,

        slowly conducting vagal fibres.