The transmission mechanism of the vagal control of the feline pylorus.
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Animals↗
Biomedical subjects
J Kewenter
Publications and source records attributed to J Kewenter.
The effects of adrenergic antagonists on the serotonin levels of feline enterochromaffin cells after splanchnic nerve stimulation.
Cut splanchnic nerves were stimulated electrically at the preganglionic level in efferent direction in anesthetized cats with the adrenals ligated bilaterally. A significant decrease of the intracellular serotonin (5-HT) levels in populations (n = 20) of individual enterochromaffin cells (EC) in the mucosa from three different levels of the small intestine (distal duodenum, mid-jejunum and terminal ileum) was obtained. The intracellular 5-HT levels before and after stimulation were studied cytofluorimetrically in biopsies treated according to the Falck-Hillarp technique. One group of cats was pretreated with propranolol prior to stimulation. This prevented the decrease in fluorescence intensity effectively. Two other groups of cats were pretreated with phenoxybenzamine or phentolamine. These drugs also blocked the expected decrease in fluorescence intensity in 7 of 8 cats. In some biopsies there was an increased fluorescence intensity after nerve stimulation in cats given propranolol or phentolamine even though the drugs themselves had no intrinsic effects on the fluorescence intensity in control animals. It is concluded that efferent electrical stimulation of the splanchnic nerves can cause a release of 5-HT from gut EC by an adrenergic mechanism.
Animals↗
Evidence for vagal enkephalinergic neural control of the feline pylorus and stomach.
The atropine- and guanethidine-resistant contraction of the cat pyloric sphincter induced by efferent stimulation of the cervical vagi, was studied with a new method for measuring transpyloric flow. The pyloric contraction was blocked in a dose-dependent manner by the opiate antagonist naloxone infused intraarterially to the pyloric region. Local intraarterial injection of morphine or enkephalinamide elicited a pyloric and gastric contraction. Leu- and met-enkephalin intraarterially elicited a pyloric contraction and a gastric relaxation. These effects could be prevented or reversed by naloxone. Immunohistochemical studies revealed a particularly rich enkephalinergic innervation of the pylorus with dense networks of varicose nerve fibers with enkephalin-like immunoreactivity both in the circular smooth muscle layer and in the myenteric plexus. Furthermore, many cell bodies of the myenteric plexus with enkephalin-like material were demonstrated. The corpus-antrum was sparsely innervated by enkephalin-like nerves to the circular muscle layer and only few immunoreactive cell bodies were observed in the myenteric plexus. These results together suggest a vagal control of the feline pylorus and stomach mediated via enkephalinergic neurons.
Animals↗
The effects of splanchnic nerve stimulation on the plasma levels of serotonin and substance P in the portal vein of the cat.
The blood levels of serotonin (5-HT) and substance P (SP) in the portal vein were studied after splanchnic nerve stimulation in the cat. The portal levels of both substances were studied before, during and after splanchnic nerve stimulation. There was a twofold increase in 5-HT during stimulation whilst the SP concentration remained unchanged. These results suggest that the nervous control of the amine release into the portal stream and the mechanism that regulates the release of the polypeptide is not the same.
Animals↗
The effect of transmural field stimulation on the serotonin content in rat duodenal enterochromaffin cells--in vitro.
The effect of transmural field stimulation (TFS)--in vitro--on the sertonin (5-HT) content in enterochromafffin cells (EC) in rat duodenum was studied with a cytofluorimetric method. TFS caused a significant 25% decrease of 5-HT in EC. The presence of tetrodotoxin or d,1-propranolol in the stimulation bath antagonized the effect of TFS. In biopsies from rats pretreated with 6-OH-dopamine TFS had no effect of the 5-HT content in EC. The results of the present study strongly suggest, that the TFS induced decrease in 5-HT content is due to a direct neural, probably beta-adrenoceptor mediated, influence on the EC.
Adrenergic Fibers↗
The vagal control of the feline pyloric sphincter.
In acute experiments on cats in chloralose anesthesia the effects of efferent and afferent electrical stimulation of the cervical vagi on an applied constant flow of saline through the feline pylorus was studied. The motor activity of the stomach was recorded simultaneously with a volume recording technique. Efferent cervical vagal stimulation caused a decrease in the transpyloric flow and an increased gastric motor activity. In a few animals the decreased transsphincteric flow was preceded by a short period of increased flow. When the transpyloric flow was reduced by splanchnic nerve stimulation or a noradrenaline infusion, vagal nerve stimulation induced an increased flow through the pylorus indicating the presence of relaxatory fibres to the pylorus within the vagi. Electrical stimulation of the central end of the ipsilateral vagal nerve in the neck, with the contralateral vagal verve left intact, resulted in a decreased transpyloric flow and relaxation of the stomach. This response could be induced with or without intact splanchnic nerves, and disappeared when the intact contralateral vagus was cut. It is concluded that the vagi mediate both excitatory and inhibitory fibres to the pyloric sphincter in the cat. A vago-vagal excitatory reflex to the pylorus can be elicited by afferent vagal nerve stimulation together with a vago-vagal relaxatory response of the stomach.
Afferent Pathways↗
On the VIP-ergic innervation of the feline pylorus.
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Animals↗
The effect of propranolol on the serotonin concentration in the portal plasma after vagal nerve stimulation in the cat.
Efferent cervical vagal nerve stimulation in the cat caused a marked increase of the portal plasma 5-HT concentration. This increase was more than two-fold within 15 min of stimulation. After cessation of stimulation portal plasma 5-HT returned to basal levels within 10 min. Treatment with the beta-adrenoceptor antagonist propranolol, in various doses (0.1-2 mg/kg b.wt.), did not abolish but significantly reduced the response to vagal stimulation, particularly during the final part of the stimulation period. The results confirm the existence of a beta-adrenoceptor-mediated release of 5-HT, but also suggest that other mechanisms for 5-HT release may be involved in the response on vagal nerve stimulation.
Adrenergic beta-Antagonists↗
The effect of parietal cell vagotomy and selective vagotomy with pyloroplasty on body weight and dietary habits. A prospective randomized study.
Body weight and dietary habits were studied in 32 male patients in a consecutive randomized series of parietal cell vagotomy (PCV) and selective vagotomy with pyloroplasty (SV + P). There were 16 patients in each group. One month after surgery all patients had lost weight. During the first 2 postoperative years following PCV most patients regained their preoperative weight. SV + P led to an impaired ability to gain weight. Following PCV the consumption of fat was reduced but the carbohydrate consumption increased, leading to an unchanged total daily energy intake. The daily energy intake decreased following SV + P in spite of an increased consumption of protein-rich foods such as meat, fish, and eggs. The decreased energy intake was due to a reduced intake of fat, sugar, and milk following SV + P. It is concluded that dumping is a contributory cause of the reduced energy intake following SV + P.
Adult↗
The effect of parietal cell vagotomy and selective vagotomy with pyloroplasty on iron absorption. A prospective randomized study.
Iron absorption from a composite meal was studied in 37 male patients before and 1 year after parietal cell vagotomy (PCV) and selective vagotomy with pyloroplasty (SV + P) in a prospective randomized series. The ability to absorb dietary non-haem iron was studied by relating in each subjects the food iron absorption to the absorption from a small dose of ferrous iron, which has been shown to be unaffected by gastric surgery. After both PCV and SV + P there was a malabsorption of food iron which was statistically significant in patients with increased iron requirements caused by phlebotomy. Malabsorption of food iron was less marked after PCV and SV + P than in patients after gastric resection, and it is concluded that there may be no need for a general prophylactic iron supplementation in patients operated on with PCV and SV + P.
Adult↗
Clinical and morphological characteristics of colitis carcinoma and colorectal carcinoma in young people.
Two series of young patients (less than 40 years of age) with colorectal carcinoma (22 idiopathic carcinomas and 25 carcinomas complicating ulcerative proctocolitis), well matched for age and sex, were compared with regard to clinical features, tumour morphology and stage, and ultimate outcome after surgery. The cure rate in both series was low. Although a failure to diagnose colitis carcinoma accurately at an early stage might have contributed to the poor results, such a delay could hardly be responsible for the bad prognosis in patients with idiopathic carcinoma. The vast majority of the patients in both groups studied had highly malignant and/or mucoid adenocarcinoma, and surgery was palliative in about 40% of the patients in both series, owing to widespread dissemination. The general impression gained from this study of factors of histologic grade of malignancy, extent of spread, and survival rate was that colorectal carcinomas in the young, irrespective of being idiopathic or complicating ulcerative colitis, run a rapid course and have a gloomy prognosis. The outloook depends largely on the biologic characteristics of the tumours concerned. The results support previous statements that prophylactic surgery is justified in patients with long-standing ulcerative colitis with total involvement of the colon, particularly in the young. Regrettably, patients with idiopathic carcinoma will not have this chance.
Adenocarcinoma, Mucinous↗
Arterio-appendiceal fistula after arterial reconstruction with synthetic graft.
A patient who 5 years previously had an aortoiliac reconstruction with a dacron graft developed intestinal bleeding. At laparotomy this was found to be due to a fistula between a pseudoaneurysm at the right iliac artery anastomosis and the appendix. Resection of the aneurysm and adjacent parts of artery and graft with additional appendectomy prevented further intestinal bleeding. A search of the literature produced only one previously reported case similar to this.
Aneurysm↗
Substance P-, VIP-, and enkephalin-like immunoreactivity in the human vagus nerve.
The human vagus nerve has been investigated for the presence of substance P (SP), vasoactive intestinal polypeptide (VIP), and enkephalin (ENK) using immunohistochemistry. After 0.5-4 hr of nerve ligation during surgical operations two right thoracic main truncs, two anterior subdiaphragmal trunks, and four anterior nerves of Latarjet were found to contain accumulation of immunoreactive material in nerve fibers above the ligation. Very high numbers of SP-, medium numbers of ENK-, and low number of VIP-immunoreactive fibers were seen. The relative proportions were similar at all levels studied. These data thus indicate the presence and axonal transport of SP-, ENK-, and VIP-like peptides in the human vagus nerve. Our observations in humans correlate well with results obtained from other species. Thus gastrointestinal vagal sensory mechanisms may be mediated by SP (and possibly VIP) and some motor mechanisms by ENK.
Endorphins↗
Evidence for innervation of the small intestine from the cervical sympathetic ganglia.
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Adrenergic Fibers↗
Cancer risk in extensive ulcerative colitis.
Two hundred thirty-four patients with extensive ulcerative colitis from the city of Göteborg, Sweden have been followed up and the cumulative risk of development of cancer of the large bowel was estimated. These patients constitute all persons in this region who developed an extensive ulcerative colitis between 1951 and 1974. All patients were followed up until December 1975. The mean observation time was 8.5 years, median value six years. Fifteen patients developed carcinoma of the large bowel. Five of the 15 patients were still alive in December 1975. The expected number of colorectal carcinomas in a matched reference group was 0.49. The cumulative incidence of carcinoma 25 years after the onset of colitis for the whole group of patients was 34% and for those who developed the disease before 25 years of age it was 43%.
Adult↗
The release of serotonin from rat duodenal enterochromaffin cells by adrenoceptor agonists studied in vitro.
The serotonin (5-HT) content of enterochromaffin cells (EC) was studied by a cytofluorimetric method in biopsies from rat duodenal mucosa after in vitro incubation with different adrenoceptor agonists and antagonists and acetylcholine (ACh). Noradrenaline (NA), Adrenaline (A) and Isoprenaline (IP) caused a decrease of 5-HT in EC down to 40--60% and for NA and A this effect was concentration-dependent. The effect was antagonized by d,1-propranolol but not by d-propranolol, metoprolol, phentolamine or phenoxybenzamine indicating that the 5-HT release from EC is probably mediated via a true beta-adrenoceptor mechanism possibly of the beta2 type. ACh also decreased the 5-HT content of EC but was much less potent than the adrenergic substances. Dopamine (DA) had no effect.
Acetylcholine↗
Ultrastructural evidence for an innervation of epithelial enterochromaffine cells in the guinea pig duodenum.
The innervation of the duodenal enterochromaffine cells (E.C.) of the guinea pig was studied at the electronmicroscopic level. Pretreatment with 5-OH-dopamine was performed to visualize catecholaminergic (CA) nervous elements. Near the basement membrane of all examined E.C. in the crypts, bundles of unmyelinated nerve processes were observed, only partly ensheathed in a Schwann cell cover. At least 4 types of processes could be observed. 1) Boutons containing only small clear vesicles, probably cholinergic fibres; 2) boutons with small clear vesicles, and in addition large (greater than 200 nm) granules with a dense matrix (P-type-fibres); 3) boutons with small electron-dense vesicles, probably CA-fibres; and 4) processes with few vesicles but having the appearance of dendrites. No typical synaptic arrangements were observed, but the minimal distance between the E.C. and the nerve bundles was 150 to 250 nm, thus well within the functional limits of the "autonomic gap". Thus epithelial E.C. may be influenced by several types of nervous elements, including CA-fibres.
Adrenergic Fibers↗
Efferent innervation of the small intestine by adrenergic neurons from the cervical sympathetic and stellate ganglia, studied by retrograde transport of peroxidase.
The nervous pathways between the small intestine of cat and guinea pig and various sympathetic ganglia were investigated by the retrograde horse-radish peroxidase (HRP) technique. HRP was injected at multiple sites in the wall of the duodenum and the first third of the jejunum. At 1--5 days after the injections, the HRP reaction product was searched for in various sympathetic ganglia. Not only the coeliac and nodose ganglia, but also the superior cervical, medial cervical, stellate and thoracic ganglia contained HRP-positive nerve cells. Crushing the cervical vagal nerve prevented the occurrence of HRP-reaction in the cervical ganglia, indicating that the HRP was transported from the gut to the cervical ganglia via axons in the vagal nerve. The results demonstrate that the sympathetic ganglia in the neck (sup, and med. cerv. ganglia and stellate ggl.) send efferent fibres to the small intestine.
Animals↗