Vagal mechanoreceptors located in the lower oesophageal sphincter of the cat.

Abstract

SUMMARY1. In anaesthetized cats, sixty-two vagal sensory units with afferent endings in the lower oesophageal sphincter were recorded by means of extracellular glass micro-electrodes implanted in the nodose ganglion.2. All the receptors had non-medullated fibres, with conduction velocities ranging from 0O8 to 1-2 m/s. From the direct stimulation of the lower oesophageal sphincter, three types of mechanoreceptors were identified. 3. Thirty-one were activated by natural stimuli: tonic contraction of the sphincter and distension elicited by the passage of a bolus. Artificial stimulation effected by digital compression was also effective. These receptors were similar to muscular endings already described in the-digestive tract. Their main characteristic, i.e. their slow adaptation, suggests that they act as sensors of sphincter opening and closure. This was corroborated by observations obtained during distension of the cervical or thoracic oesophagus; a maximum decrease occurred in the lower oesophageal sphincter mechanoreceptor discharge when the distension was produced between 9 and 12 cm from the lower oesophageal sphincter.4. Twenty-nine endings were found in the superficial layers mucosaee). Contrary to the muscular receptors, the mucosal receptors were not affected by normal contractions or distensions of the lower oesophageal sphincter. They were activated only by strong stimuli like digital compression or distension achieved with a balloon. In addition, mucosal stroking was a potent stimulus. Whatever the stimulus used, the mucosal receptors showed rather rapidly adapting discharges. These receptors should be considered to be sensors of bolus consistency.5. Two mechanoreceptors, located in the serous membrane ofthe lower oesophageal sphincter, were identified by touching or by stretching. Their discharges showed that they belonged to the rapidly adapting type.6. A comparison of the three types of receptors found in the lower oesophageal sphincter is made with known digestive endings and their possible role is discussed.

Histological Characteristics of the Lower Oesophageal Sphincter in the Cat

“…Although these results concern the oesophagus, they lead one to suppose that the muscularis mucosae of the LOS plays a role in the closure mechanism of the sphincter. This hypothesis is also supported first by the abundance of vagal mucous mechanoreceptors recently demonstrated in LOS area [Clerc and Mei, 1983a], and sec ondly by the existence of the extension of the muscularis mucosae at LOS level.…”

Transient Lower Esophageal Sphincter Relaxation and Esophageal Motor Response

“…The immediate onset of EMRs after TLESRs in the animal model indicates a reflex pathway, and the dependence of the EMR amplitude on the external cuff and endoluminal balloon pressures suggests that mechanoreceptors in the GEJ [20,[32][33][34] play a role in the mediation of post-TLESR EMRs. This hypothesis is supported by the observation that individuals in the control group had as many EMRs as the GERD patients despite significantly fewer TLESRs, as the control group had a significantly higher LESP (which could be interpreted as esophageal outflow obstruction, from the GERD patient's point of view).…”

Correlative Light and Scanning Electron-Microscopic Study of Feline Gastric Mucosa: The Cardiac Region (<i>Pars cardiaca</i>)

“…This is especially true in the cat, even though it has been used recently as an experimental animal [Biancani et al. 1982;Clerc and Mei. Supported by LSU and UT College of Veterinary Medicine.…”

“…1980;Clerc. 1983: Clerc andMei, 1983] and pathology [Bishop el al.. 1979]. Bensley [1902] concluded that the width of the cardiac gland region depends upon the species of animal.…”