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THE EFFECT ON THE STOMACH OF STIMULATION OF THE PERIPHERAL END OF THE VAGUS NERVE
Author(s) -
M'Crea E. D.,
M'Swiney B. A.,
Stopford J. S. B.
Publication year - 1925
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0370-2901
DOI - 10.1113/expphysiol.1925.sp000355
Subject(s) - stimulation , tonic (physiology) , contraction (grammar) , peripheral , stimulus (psychology) , medicine , splanchnic nerves , anesthesia , neuroscience , anatomy , psychology , psychotherapist
Stimulation of the peripheral cut end of either vagus by means of the faradic current will, if the organ be in a state of “hypotonus,” either initiate movements in the quiescent stomach, or, if movements are present, augment and sometimes accelerate them. A rise of entogastric pressure may accompany these movements. The contractions produced are indistinguishable from accentuated normal movements‐they are an exaggeration of the normal‐unless the stimulus be exceptionally strong, when a tonic contraction may result : from this, however, “escape” shortly occurs. The motor effect is preceded by a brief interval or latent period of some three seconds, and should the viscus be initially in a condition of “hypertonus,” this is followed by a period during which movements, if present, cease, and relaxation occurs. Augmented or initial contractions ensue later, but may be delayed until after the cessation of stimulus : there is not necessarily a restoration of entogastric pressure. The pre‐existing state of the peripheral mechanism governs the response to stimulation, the most marked results being obtained with the active organ, the least with the passive. The X‐ray picture on vagal stimulation shows that the effects on function are augmentor and accelerator: food in the cesophagus passes through the cardia, the waves of contraction are deeper than normal, and the pylorus functions rapidly, food leaving through the sphincter before every antral contraction. A brief preliminary relaxation may be observed. These effects remain unchanged by alterations of anæsthetics, decerebration, or splanchnic section. A vaso‐constrictor effect may be obtained on stimulation of the peripheral cut end of the vagus. The first part of the duodenum functions with the stomach and is controlled by the vagus in a similar manner. Stimulation of the intact nerve, the other being undivided, gives variable results, depending on the preexisting state, and on whether the centripetal or centrifugal influences predominate. We desire to make clear that our use of the entogastric pressure is only as an index of the activity or inactivity of the organ, and that by it we are endeavounrng to gauge the condition of the peripheral mechanism. We use the digesting or quiescent viscus in order to obtain variations in this state of the peripheral mechanism, and these are demonstrable by the entogastric pressure, latent period, and “response.” The majority of our findings may be summarised as follows:— 1. The primary effect of stimulation of the peripheral cut end of either vagus on the stomach is dependent on the existing condition of the peripheral mechanism (“tonus”), and may be inhibitor or augmentor. 2. The inhibitor or augmentor effect may involve both “tonus” and movement. 3. The final effect of stimulation is to bring about the augmentation of existing movement or to initiate movement. 4. “Tonus” and contraction may vary inversely or directly.