@entity3774 alpha augments the response to parasympathetic fibre stimulation in an isolated innervated preparation of @entity95 XXXX .

@entity825 @entity4033 @entity1672 @entity32 @entity1030 @entity1022 @entity95 @entity3897 @entity3774 @entity934
1. We have devised an isolated innervated preparation of @entity95 @entity825 in which parasympathetic fibres can be stimulated either pre- or postganglionically. 2. Contractions induced by transmural stimulation of the tracheal smooth muscle and by stimulation of the proximal end of the vagus nerve were both inhibited by @entity1022 and @entity3897 indicating that @entity934 release from neural fibres was responsible for each contraction. 3. Only the contraction induced by stimulation of the vagus nerve was significantly inhibited by @entity4033 indicating that this response was mediated by preganglionic stimulation. 4. The contractions induced by both pre- and postganglionic stimulation were potentiated by @entity3774 (PGF2 alpha). The potentiation was short-lasting and could not be repeated in the same preparation. 5. In contrast @entity1672 (PGD2) inhibited each form of stimulation-induced contraction in a dose-related manner. 6. In separate experiments PGF2 alpha also potentiated the contractile response to exogenous @entity934 in isolated non-innervated tracheal segments. This localizes the action of PGF2 alpha to the smooth muscle. 7. These effects of PGF2 alpha may be important in the @entity32 which accompanies @entity1030 .
