Vagal Section Research Articles

Effects of cold, eating, efferent nerve stimulation and angiotensin on heart rate in sheep before and after autonomic blockade

1. Effects of the natural stimuli of cold exposure and feeding on heart rate were tested in conscious sheep in which blockade of the cardiac efferent nerves was achieved by administration of propranolol and atropine. Effects of direct nerve stimulation, isoproterenol and angiotensin on heart rate before and after autonomic blockade were studied in acute preparations anaesthetized with pentobarbitone sodium.2. Propranolol reduced the extent of cardioacceleration induced both by exposure to cold and by eating. Heart rate in propranolol treated animals exposed to cold did not exceed about 120 beats/min. During eating, heart rate in propranolol treated animals showed no upper limit and increased on occasions to over 170 beats/min.3. Heart rate in conscious sheep following administration of atropine and propranolol was about 110 beats/min; in anaesthetized sheep following vagal section and propranolol it was usually about 120 beats/min. This was taken as intrinsic heart rate.4. Angiotensin administered to normal anaesthetized sheep usually reduced heart rate. After vagal section and propranolol, angiotensin injection usually, and angiotensin infusion invariably, increased heart rate.5. It was concluded that there exists in sheep a mechanism which during eating elevates heart rate by a means other than through the parasympathetic and sympatho-adrenal systems. It is suggested that this mechanism involves a direct chronotropic effect of angiotensin secreted in association with eating.

Effects of bilateral vagotomy on renal function in the rat.

Renal function was studied in rats before and after section of the vagus nerves at the level of the common carotid arteries. In the control group of rats, sodium output and volume rate of urine flow increased following vagal section but glomerular filtration rate did not change. This response was not altered in other rats by desoxycorticosterone acetate, vasopressin, or renal nerve section. This response was similar to that seen in rats in which both common carotid arteries had been occluded. The natriuresis following bilateral vagotomy did not occur in rats in which the blood pressure was prevented from rising by means of aortic constriction. It is concluded that a natriuresis does occur following bilateral vagotomy. This natriuresis may be a result of the effect of arterial blood pressure following the vagotomy.

Vagotomy and drainage procedures for duodenal ulcer incidence and effect of incomplete vagal section.

One hundred and seventy-one patients were treated by vagotomy and drainage for duodenal ulcer. When performed electively, the mortality was low (0.9%). For massive, continuing hemorrhage the mortality was high (22.2%). There was an 11.1% overall incidence of ulcer recurrence. The number of vagal trunks resected did not establish the completeness of vagotomy. Insulin testing was performed postoperatively in 60 patients. Of these, 22 (37%) were positive. A positive insulin test was associated with a high incidence of recurrent ulcer (60%). There were no recurrences in those patients with negative or equivocal Hollander tests. We believe that routine postoperative insulin tests are a valuable prognostic guide.

Influence of vagotomy in the tench Tinca tinca during a multicationic load (dilute salt water). Variation in the cations Na+, K+, Ca++ and intensity of tissue respiration

Respiratory ionic content (Na+, K+, Ca++) of hepatic tissue and ionic excretion measurements were performed in the TenchTinea tinea kept in diluted sea water. After bilateral section of parasympathetic system, the changes of Na/K value are less than in fresh water. The survival and hepatic O2 uptake were the same. It is suggested than after both vagi section sea water Ca++ allowed a best osmoregulation in this species.

Critical appraisal of vagotomy and pyloroplasty. Treatment of peptic ulcer.

The reintroduction of pyloroplasty and the combination of this procedure with vagus nerve section have provided a relatively simple but physiologic approach to the surgical treatment of duodenal ulcer. Although widely accepted on a physiologic basis, the exact role of this procedure in the surgical treatment of duodenal ulcer remains unclear to many clinicians. The present study is a critical appraisal of the results and complications of this operation performed on 500 patients, 317 of whom were followed up two to eight years. The ulcer diathesis was controlled in 84% of the patients; 13% of the patients required medication for occasional but regularly occurring symptoms and 3% had results classified as poor. The surgical mortality for the entire group was 4.2%. The surgical mortality in 50 patients operated on as emergencies during the period of uncontrolled and massive hemorrhage was 24%. In contrast, there was no operative mortality in 36

The physiological effect of acute vagal section on canine biliary dynamics

The effects of acute vagal section upon canine biliary dynamics are reported. The most important dynamic change is the decrease in passage pressure at both the cystic duct sphincter zone and the choledochal duodenal junction sphincter.

Alterations in Muscular and Electrical Activity of the Stomach Following Vagotomy

IN 1943, Dragstedt and Owens¹introduced bilateral section of the vagus nerves as a therapeutic procedure for treatment of duodenal ulcer. Since that time, this operation with modifications has become firmly established as the procedure of choice in the surgical treatment of duodenal ulcer. Bilateral vagotomy not only eliminated the cephalic phase of gastric secretion, thus providing therapeutic benefit to the duodenal ulcer patient, but also abolished the cephalic phase of gastric motor activity. At the time vagotomy was introduced as a therapeutic procedure a wide difference of opinion existed about the long-term effect of bilateral vagal section on gastric motor behavior. The work of McCrea et al²indicated that there was a more rapid initial emptying time of the stomach following vagal section but that the total emptying time was essentially unchanged. Meek and Herrin's³series of experiments indicated that the consistency of the meal was

Variations in salt concentration in the tench (Tinca tinca L.). Effect of vagotomy on respiratory intensity and content of water and cations (Na+ and K+) of liver tissue

Vagus nerve section was performed on a stenohaline species: the tench (Tinca tinca L.). The oxygen consumption and Na+ content increased in both tap water and after transfer to salt water. It is suggested that the vagus nerve plays a role in water and electrolyte flux in this fish.

Reflex inhibition of sympathetic vasoconstrictor activity at a peripheral locus.

Section of the lumbar sympathetic chain just proximal to a stimulating electrode most often results in a large increase in the neurogenic constrictor response to stimulation. The increase could not be accounted for by removal of sympathetic discharge present before section, or by an increase in vascular sensitivity to either exogenous or neurogenically released adrenergic amine. The increased neurogenic constriction is attributed to the removal of an inhibition present before nerve section. The inhibitory fibers are distributed over the classic sympathetic outflow and take origin at least in part at a supraspinal level. The inhibition is lost or markedly reduced by hypotension, spinal cord section, spinal anesthesia, section of the preganglionic sympathetics, or by section of the sinus and vagus nerves. The inhibition, lost by sinus and vagus nerve section or by induction of hypotension, can be restored by stimulation of the central ends of the cut nerves and by replacement of blood, respectively. It is concluded that the conventional pressoreceptor reflexes act to inhibit vasoconstrictor tone, at least in part, at a site in the vasoconstrictor pathway peripheral to the spinal cord.

A gastric phase of pancreatic secretion.

1. Extracts of antral mucosa increase the output of pancreatic amylase. They do not stimulate the resting pancreas of the anaesthetized cat to secrete juice, but have a slight ;secretin-like' effect on a pancreas already responding to endogenous or exogenous secretin.2. In animals with the vagus and splanchnic nerves cut instillation of meat extracts or acetylcholine into the antrum stimulates gastric acid and pancreatic amylase secretion. These responses can be prevented by injection of atropine or cocainization of the antral mucosa.3. In animals with the splanchnic nerves cut but the vagus nerves intact, distension of the body or antrum increases the output of amylase. After vagal section distension of the body has no effect on the pancreas, but the response to antral distension is still present.4. It is concluded that there is a gastric phase of pancreatic secretion which, in the cat, is almost entirely a stimulation of enzyme output. A vago-vagal reflex pathway is required for the pancreatic response to mechanical stimulation of the body of the stomach, and may be involved in the response to antral stimulation. Chemical and mechanical stimulation of the antrum produces a hormonally mediated increase in pancreatic enzyme secretion. The effects of atropine and cocaine on this response are consistent with the view that the release of the antral stimulant depends on a local cholinergic reflex pathway in the antrum.

Effects of respiratory center activity on the heart.

Rhythmic fluctuations in heart rate and ventricular contractility at the frequency of the respiratory movements were observed in innervated, isovolumetric, canine, left ventricle preparations. The heart rate and contractility waves probably represent the radiation of activity from the respiratory centers to the cardiac autonomic centers within the central nervous system. In spontaneously beating hearts, the respiratory cardiac arrhythmia is mediated via the vagi predominantly, although a slight arrhythmia is still evident after bilateral vagotomy. The greater the vagal tone, the greater is the amplitude of the arrhythmia. In paced hearts, the contractility waves exhibit significantly greater phase lags than do the heart rate waves in unpaced beats. The magnitude of the contractility waves varies inversely with the respiratory frequency. These waves are more prominent after bilateral vagotomy. Therefore, sympathetic influences appear to predominate in the mediation of the contractility waves, although the change in wave amplitude after vagotomy must be ascribed partly to the deceleration of respiratory frequency which occurs after vagotomy. The contractility waves represent rhythmic augmentations of contractility above a base line level after vagal section.

Effects of cervical vagal nerve section and stimulation on the jejunal and ileal motility

Effects of cervical vagal nerve section and stimulation on the jejunal and ileal motility

COMPLETE VAGOTOMY AND ITS CONSEQUENCES: FOLLOW-UP OF 146 PATIENTS.

Division of all vagal branches to the stomach may be important in the treatment of duodenal ulcer. As long ago as 1947 Dragstedt and his colleagues pointed out that if a branch of the vagus is inadvertently missed at operation there may be reactivation of the whole of the glandular apparatus, return of high acid secretion, and consequent recurrence of ulc?ration ; more recently Murray (1962a) discussed the mechanism of return of nervous activity. In 1958 B?rge and Vane introduced a method of testing for completeness of vagal section at the time of operation, and Clark and Murray (1963) investigated the usefulness of the test in 100 patients. This report is con cerned with a follow-up from two to five years after operation in which complete vagotomy was carried out. In all cases the drainage procedure was gastro-enterostomy. An attempt has been made to answer a number of questions. Does complete vagotomy confer an immunity from recurrence of ulc?ration ? How does morbidity after complete vagotomy compare with that after incomplete nerve section and after partial gastrectomy ?

Indications for section of the cricopharyngeus muscle

I N THE AVERAGE general hospital of several hundred beds a few patients will be seen each year with dysphagia referable to the cervical portion of the gullet. The act of swallowing represents a complex neuromuscular reflex mechanism in which the cricopharyngeus muscle plays a small but important role. While this mechanism may become deranged at many points, malfunction of the cricopharyngeus muscle may occasionally determine whether the patient can swallow with minimal satisfaction. In some instances simple sectioning of the muscle will be of considerable value. It is the purpose of this paper to point out those conceivable instances in which sectioning the muscle is indicated. After Valsalva [1] first described the cricopharyngeus muscle (Fig. 1) in 1717 many studies followed over the years regarding this muscle by anatomists, physicists, radiologists and clinicians; but there were definite limitations even with the fluoroscope until cinefluoroscopy permitted functional studies in slowed motion. Many contributions which have been made have been reviewed in chronologic summary by Kirchner [Z]. Probably the best and most recent study of the cricopharyngeus muscle was that published by Kirchner in 1958. He used a pressuresensitive recording device attached to a tube with multiple balloons to study the effect of stimulation or interruption of the cervical sympathetic or parasympathetic trunks (Fig. 2) on the motor activity of the cricopharyngeus muscle in dogs. He reached the following results and conclusions : “(1) The cricopharyngeus muscle was found by pressure recordings to be in a constant state of tonus during its resting stage. (2) During normal deglutition the muscle frrst relaxes then contracts to a pressure level equal to or higher than its resting pressure. (3) Unilateral vagus section at base of skull diminishes slightly the relaxation phase of the muscle during swallowing but does not produce dysphagia in the dog. (4) Bilateral vagus section at base of skull abolishes the relaxation phase and produces severe dysphagia during the dog’s remaining hours of life. (5) Faradic stimulation of the vagus branch to the cricopharyngeus produces a sharp relaxation of pressure. (6) Stimulation of the superior cervical sympathetic ganglion produces a sharp rise in pressure. (7) Relaxation is mediated by the parasympathetic fibers; contraction is mediated by the sympathetic. (8) Dysphagia may result from increased tonus in the cricopharyngeus as a result of sympathetic overactivity in lesions affecting the vagus nerves between the nucleus ambiguus and the ganglion nodosum. Surgical treatment of this condition would require division of either the muscle itself, or its sympathetic nerve supply.”

Cardiovascular responses to vagal stimulation and cardioaccelerator nerve blockade in birds

1. 1. Systemic arterial and central venous pressures and heart rate have been recorded continuously in domestic ducks and seagulls during vagal sectioning and subsequent stimulation of the various cut ends of the vagi. The same parameters were also recorded during administration of the sumpathetic blocking agent, Alderlin. 2. 2. Bilateral vagotomy caused a conspicuous increase in heart rate (up to 65 per cent increase) and systemic arterial blood pressure. The breathing rate dropped precipitously. 3. 3. Stimulation of the peripheral ends of the cut vagi induced a marked bradycardia. The right peripheral end was most effective in this respect. 4. 4. Stimulation of the peripheral left vagus end with the right vagus intact gave in addition to the bradycardian an increased breathing rate. During stimulation of the central end, the heart rate and blood pressure fell, while the venous pressure rose conspicuously. A prompt apnea accompanied these responses. A peripheral stimulation of the left vagus after sectioning of the right gave no tachypnea. 5. 5. Stimulation of the right central vagus with the left intact gave a marked increase in both arterial and venous pressures as well as heart rate. After sectioning of the left vagus a stimulation of the right central end still gave a marked tachycardia and pressor effect and elicited apnea and central venous pressure rise. 6. 6. The results from vagal sectioning and stimulation are discussed in relation to available information from studies on other vertebrates. The birds investigated seem to differ from mammals with respect to the responses obtained when stimulating the central ends of the right and left cut vagus. 7. 7. The results of experiments with the sympathetic blocking agent, Alderlin, are strongly suggestive that the resting sympathetic influence on the avian heart is considerably higher than in mammals. This factor augments the regulatory efficiency of the cardiac innervation in birds.

Phosgene Poisoning as an Example of Neuroparalytic Acute Pulmonary Edema: The Sympathetic Vasomotor Reflex Involved

SUMMARY Conditions of acute pulmonary edema are classified into two great groups, according to certain empirically useful anatomic, physiologic, pharmacologic, clinical and radiologic criteria. The hyperactive-sympathetic group is characterized by diffuse lung hyperemia, pulmonary hypertension, amelioration by sympatholytic agents, systemic hypertension and uniformly dense lung fields; it includes epinephrine toxicity and brainstem irritation. The hypoactive-sympathetic or neuroparalytic group is characterized by patchy lung hyperemia, pulmonary normo- or hypotension, non-amelioration by sympatholytic agents, systemic normo- or hypotension and generalized reticulogranular images in the lung fields; it includes vagal section, so-called high altitude pneumonia, hyaline membrane disease, explosive recompression, probably paroxysmal nocturnal dyspnea, and phosgene poisoning. The basic assumption of this classification, specifically in relation to the neuroparalytic group, is tested by direct assay of total electrical activity of the right cervical sympathetic nerve in the rabbit before and after a lethal dose of phosgene. An immediate abrupt marked drop in systemic sympathetic outflow which precedes the lung changes occurs upon phosgene poisoning in the rabbit. Other data are marshalled to establish that the sympathetic neuroparalysis of phosgene poisoning is reflex in nature and associated with vasoconstriction of the lung vascular bed, such pulmonary shutdown being essentially a post-capillary phenomenon. The autonomic sensorimotor negative feedback reflex thus identified as controlling the vascular dynamics of the lung is presented as coursing afferently with the vagus, synapsing at the bulbar reticular formation, and coursing efferently with the upper thoracic sympathetics.

EFFECT OF VAGOTOMY, VAGUS STIMULATION AND VARIOUS DRUGS ON THE SUBSTANCE P CONTENT IN THE SMALL INTESTINE OF THE RABBIT.

AbstractCervical vagotomy significantly increased the Substance P (SP) content in the rabbit's small intestine, from 2.8 ± 0.2 U/g to 7.2 ± 0.6 U/g. Stimulation of either right or left vagus in the neck significantly decreased SP in the same tissue from 2.8 ± 0.2 to 1.0 ± 0.2 U/g. The SP values increased 15 min after cessation of stimulation and reached control values within 30 min. Physostigmine significantly decreased the SP content in the rabbit's intestine to 1.7 ± 0.2 U/g; while no definite effect was observed after administration of hexamethonium, chlorisondamine, atropine, reserpine, chlorpromazine, p‐hydroxymercuribenzoate or nicotine. It is suggested that vagus stimulation and physostigmine deplete the SP stores in some peripheral nervous structures in the intestine. Conversely, vagus section may allow a replenishing of the stores.

Terminal esophageal (vestibular) spasm after vagotomy.

Vagotomy, as a surgical approach to the treatment of peptic ulcer disease, was first described by Exner and Schwarzmann in 1912, 1 but it has been primarily as a result of the more recent work of Dragstedt 2,3 that this procedure has gained increasingly widespread acceptance. The occurrence of achalasia of the esophagus as a complication of vagotomy has received scant mention in the accumulating literature on this subject. 4-8 Although this condition occurs most uniformly after cervical or high intrathoracic section of the vagus nerves in dogs, 9 it has only rarely been encountered after vagus section in man. Dragstedt attributes this to the fact that the vagi are usually divided only a short distance above the hiatus and has postulated that damage to the vagus nerves higher up might produce spasm of the cardia in man as it does in the lower animals. Ivy, 10 in discussing vagotomy,

Dynamics of cardiac activity and the P wave of the electrocardiogram with stimulation of the vagus following disruption of the inhibitory effect.

Acute experiments were performed on dogs under morphine-urethane anesthesia. A study was made of the cardiac activity and dynamics of the ECGP wave with relation to the value of the mean arterial pressure and the rhythm of cardiac activity in prolonged stimulation of the peripheral section of divided vagus after inhibition disruption (vagus-escape). As demonstrated, in prolonged stimulation of the peripheral section of the vagus after vagus-escape the sinus rhythm appears with the frequency of cardiac contractions of 50–60 per minute and with the achievement of the mean arterial pressure of 70–80% of the initial level. The stable form of cardiac contractions thus established resembles the effect on the heart of the vaguscenter characterized by slowed down rhythm of cardiac activity with retention of large systolic blood volume, maintaining the mean arterial pressure at a sufficiently high level. Atrioventricular rhythm and artioventricular block were observed with a lower mean arterial pressure and a slower rhythm of cardiac contraction.

Respiratory response to forward acceleration compared with chest compression in dogs.

Six mongrel dogs were studied to determine if the increases in frequency of breathing characteristic of both chest compression and forward acceleration are initiated by the same vagal reflex. Since vagal section only abolished the response to chest compression, it is assumed that some other mechanism is primarily responsible for the rate increase characteristic of forward acceleration. Experiments are also described which suggest that the increased respiratory frequency may be attributed to a hypoxic drive. Note: (With the Technical Assistance of N. P. Clark) Submitted on December 7, 1961