The gastrointestinal tract is innervated by extrinsic primary afferent neurones which arise from two different sources. Spinal afferents originate in the dorsal root ganglia whereas vagal afferents have their cell bodies in the nodose ganglia.1 Most of the spinal afferents which supply the stomach and intestine of rodents contain neuropeptides such as calcitonin gene related peptide (CGRP) and the tachykinins, substance P and neurokinin A as their chemical messengers.2 In terms of modality, these neurones are to a considerable extent nociceptive afferents and are thought to serve tissue homeostasis in a dual manner. On the one hand, afferent neurones convey information to the central nervous system and thus lead to the sensations of discomfort and pain and elicit autonomic and endocrine reactions. On the other hand, peptidergic afferent neurones can release vasoactive neuropeptides from their peripheral endings and thus enhance the resistance of the tissue to injury and aid the repair of damaged tissue.3 4 This latter function is borne out by the abundance of CGRP and substance P containing axons around arterioles in the rat gastric submucosa.5

The overall aim of our studies has been to elucidate the role of afferent neurones in the vascular regulation of the stomach …