Читать книгу The Esophagus - Группа авторов - Страница 136

The esophagus receives vagal input providing sequential activation to both the striated and smooth muscle segments during both primary and secondary peristalsis. Figure 5.11 illustrates this vagal activity in the baboon and opossum [39, 214]. The findings in the opossum indicate two different timings of vagal firing patterns: an early, rapid‐sequence group that would fit with early activation of inhibitory neurons; and a later, slower‐sequence group that mirrors the timing and velocity of the peristaltic contraction. It is not known if two firing patterns are present in other species. If initial inhibition and subsequent excitation is the function of these two groups, it has been assumed that the early group excites the inhibitory neurons, while the later group excites the excitatory neurons along the smooth muscle esophagus. It is unclear if the vagal fibers go directly to these neurons or are routed through interneuronal circuitry. However, this input must integrate effectively with the intramural mechanisms, including this circuitry and the muscle itself.

Figure 5.11 Vagus nerve firing patterns with esophageal peristalsis. The firing patterns of the vagus nerve during a swallow in the opossum (A) and the baboon (B). In the opossum, there is an early and a late sequential firing pattern, the later pattern corresponding to the timing and velocity of the esophageal peristaltic wave. In the baboon, only a sequential firing pattern timed with the presence of the esophageal contraction along the esophagus was recorded. UE, upper esophagus; ME, mid esophagus; LE, lower esophagus.

Sources: (A) Adapted from Gidda and Goyal [164] (B) Roman [39] with permissions of Elsevier.