Dorsal medullary injection of atrial natriuretic factor (ANF) excites vagal efferents and inhibits gastric motility.

Atrial natriuretic factor (ANF)-immunoreactive fibers are found in the dorsal motor nucleus of the vagus (DMN) along with receptors for that peptide. Previous investigations showed that ANF injections into the DMN did not influence cardiovascular functions. Since the DMN is largely (but not exclusively) involved with the control of gastrointestinal functions, we hypothesized that ANF may act on gastric, rather than cardiovascular vagal efferents. Injections of ANF (20 pmol rat atriopeptin III in 20 nl) into the DMN evoked a vagally dependent reduction in gastric motility. In a separate electrophysiological study, 10 of 15 (66%) antidromically identified DMN neurons were excited by micropressure-applied ANF (25-500 fmol in 50-1000 pl). We propose that ANF-containing neurons in the DMN reduce gastric motility by activating vagal efferents that synapse with inhibitory neurons in the gastric enteric nervous system.