AN IN-VITRO STUDY OF THE PROPERTIES OF VAGAL AFFERENT-FIBERS INNERVATING THE FERRET ESOPHAGUS AND STOMACH

1. A novel preparation of the oesophagus with attached vagus nerve fro m the ferret maintained in vitro was used to study the properties of s ingle vagal afferent nerve fibres with identified receptive fields. 2. Recordings were made from three types of gastro-oesophageal vagal aff erent fibres that were classified on the basis of their sensitivity to mechanical stimulation. There were those responding to mucosal stroki ng (mucosal receptors), to circular tension (tension receptors) and th ose responding to mucosal stroking and circular tension, which we have termed tension/mucosal (TM) receptors. 3. The conduction velocities f or mucosal, TM and tension receptor fibres were 6.38 +/- 1.22 m s(-1) (n = 22), 6.20 +/- 1.49 m s(-1) (n = 13) and 5.33 +/- 0.86 m s(-1) (n = 22), respectively. 4. Receptive fields of afferents showed random to pographical distribution by fibre type and conduction velocity. They w ere found mainly distal but also occasionally proximal to the point of vagal dissection. 5. Twenty-eight per cent of mucosal, 63% of TM and 43% of tension receptors responded to one or more drugs or chemical st imuli applied to the receptive field. 6. In conclusion, this experimen tal preparation provides evidence for the existence of three types of oesophageal vagal afferent fibre, namely mucosal, tension and the newl y identified tension/mucosal receptors.