Response of Single Vagal Afferent Fibres to Mechanical and Chemical Stimulation of the Gastric and Duodenal Mucosa in Cats

Abstract

Single afferent fibres were dissected from the cervical vagus of adult cats and their response to mechanical and chemical stimulation of the gastroduodenal mucosa studied. All the units responded to light phasic mechanical stimulation of the mucosa but two different types of unit could be distinguished on the basis of their response to chemical stimulation. One type of unit responded to acidification of the mucosa while the other responded to application of high pH solutions to the mucosa. Each unit responded to one or other of these two forms of stimulation but not to both. Nor did any unit respond to any other form of chemical stimulation. Other functional characteristics, the location of the mucosal endings and the pathways of the units between the abdomen and neck are described. The possible role of these afferent units is discussed.

Proceedings of the Physiological Society, 18–19 January 1974, St.Thomas's Hospital Meeting: Communications

“…This first peristaltic wave has a velocity of 28 + 2 cm/sec. Iggo (1957) and Davison (1972). These units in the rat more closely resemble the reticulo-epithelial and abomasal endings described recently in the sheep (Harding & Leek, 1972a, b).…”

Mucosal receptors in the gastric antrum and small intestine of the rat with afferent fibres in the cervical vagus.

“…4), due possibly to phasic stimulation of the mucosaby the balloon (cf. Mei (1970), Davison (1972b) and Harding & Titchen (1975)). This difference in response to distension clearly distinguishes these units from the slowly adapting mechanoreceptor afferent fibres which also can be isolated from the cervical vagus of the rat (Clarke & Davison, 1975, 1976Davison & Clarke, 1977).…”

“…In only a small proportion of such studies has an attempt been made to investigate the chemosensitivity of afferent nerve endings. Iggo (1957) and Davison (1972b) have described mucosal endings of single vagal fibres in the stomach and small intestine of the cat which respond to mechanical and chemical stimulation of the mucosa. Harding & Leek (1972a, b) and Leek (1972) have isolated vagal afferent units with chemosensitive endings in the abomasum and reticulum of the sheep and further details are provided in recent reviews (Leek, 1977;Leek & Harding, 1975).…”

Autonomic nervous contributions to the frequency of distension induced gastric motility in anesthetized dogs.

“…The ECA frequency was shown to be decreased by both mechanical (gastric distension) and chemical (instillation of acidic or alkaline solution) stimulation (KUWAHARA,1983a), and changes in ECA frequency following chemical stimulation were regulated by the vago-vagal reflex (KUWAHARA, 1983b). The mechanoreceptors, like the chemoreceptors, are located in the gastric wall and discharge impulses in both vagal and splanchnic nerves (DAVIsoN, 1972;IGGO, 1955IGGO, , 1957MORRISON, 1977;PAINTAL, 1954). These mechanoreceptors are stimulated by both passive gastric distension and gastric contraction.…”