Selective regulation of acid, pepsinogen, and bicarbonate secretion in the stomach by different C-fiber populations of vagus nerve.

Acute experiments on anesthetized rats showed that group B nerve fibers of the subphrenic portion of the vagus nerve do not participate in the regulation of gastric secretion. Gastric acid production is mainly controlled by fast C-fibers (2.11 0.09 m/sec), while secretion of pepsinogen and bicarbonates depends on activity of both fast and slow (0.95 0.11 m/sec) C-fibers. Some fast conduction C-fibers stimulating the release of bicarbonates in the stomach are capsaicin-sensitive afferents. The local effect of these afferents depends on cholinergic transmission and most probably it is mediated via its modulation.