INVOLVEMENT OF THE VAGUS NERVE, SUBSTANCE-P AND CHOLECYSTOKININ IN THE REGULATION OF INTESTINAL BLOOD-FLOW

Intestinal blood flow was recorded in anesthetized rats and cats using laser-Doppler flowmetry (LDF). This new technique provides continuous and accurate measurements of the intestinal blood flow, without affec ting the blood circulation. Electrical stimulation (1 ms, 5-30 V, 5-50 Hz) applied either afferent or efferent vagal fibres elicited changes in the intestinal blood flow consisting mainly of increases. Similar results were obtained upon applying chemical stimulation to intestinal sensory endings using cholecystokinin (CCK) or substance P (SP; 10-20 mu g/kg intravenously given). Bilateral vagotomy and atropine treatme nt markedly reduced or suppressed these vascular effects. In addition, experiments in which the activation of gastrointestinal afferents wer e activated by applying electrical stimulation to the abdominal vagal nerves yielded similar results. Finally, these effects were reduced af ter selectively severing vagal afferents. It is concluded that intesti nal blood changes may be triggered by activation of the sensory ending s from the digestive organs through the vagal nerves.