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C Roman

Publications and source records attributed to C Roman.

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The role of oesophageal and intestinal receptors in the control of gastric motility.

The aim of this work was to characterize the discharge pattern of vagal efferent fibers supplying the stomach, and the modifications of this pattern induced by stimulation of oesophageal or intestinal receptors. The experiments were performed on dogs in which the central end of the left thoracic vagus had been sutured to the peripheral end of the left phrenic nerve. In such preparations, the activity of the motor units of the reinnervated left hemidiaphragm indicated the activity of vagal efferent fibers. After the left hemidiaphragm had been transformed into subcutaneous muscle, it was possible to study, using electromyography, in the conscious dog, the discharge of efferent vagal fibers which originally supplied the stomach. All the gastric vagal efferent fibers presented a spontaneous discharge with a very low frequency (0.1 Hz less than f less than 5 Hz). The firing of some fibers was increased each time the gastric motility was enhanced: these fibers were considered to be excitatory fibers. In contrast, other fibers exhibited an opposite discharge pattern and they were considered to be inhibitory fibers. Among all the gastric fibers whose activity was recorded in this study, some of them presented a modification of discharge during the receptive relaxation of the proximal stomach produced by an oesophageal distension. The discharge of excitatory fibers was suppressed while that of the inhibitory fibers was markedly increased. Taking into account these modifications of discharge, parallel to the relaxation of the proximal stomach, it was assumed that these fibers originally supplied the gastric fundus.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

New insights into the organization of a gastroduodenal inhibitory reflex by the coeliac plexus.

The mechanisms involved at the prevertebral ganglionic level in a gastroduodenal inhibitory reflex were investigated in the rabbit on an in vitro preparation of the coeliac plexus connected to the stomach and duodenum. Intraluminal gastric and duodenal pressures were measured using water-filled balloons. Gastric distension inhibited duodenal motility via a nerve reflex which was abolished by section of the nerves connecting the coeliac plexus to the viscera. Superfusion of the coeliac plexus with a low Ca(2+)-high Mg2+ solution abolished the gastroduodenal inhibitory reflex, indicating a synaptic link at the ganglion level. The reflex was unaffected by superfusion of the coeliac plexus with hexamethonium and tubocurarine, ruling out a nicotinic mechanism. The reflex persisted when the coeliac plexus was superfused with tetrodotoxin or when the nerves connecting the coeliac plexus to the viscera were superfused with a Na(+)-free solution; these results indicate that the reflex does not involve sodium-dependent action potentials. Moreover, superfusion of the nerves connecting the coeliac plexus to the viscera with a calcium blocker or with a Ca(2+)-free solution also failed to abolish the reflex, suggesting that calcium-dependent action potentials are not involved. Our study demonstrates that a gastrointestinal inhibitory reflex via the coeliac ganglion is not based on fast synaptic inputs or action potentials. These results provide new insights concerning the physiology of the sympathetic prevertebral ganglia.

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