EXPERIMENTAL EVALUATION OF THIAZIDES AND POTASSIUM AS A CAUSE OF SMALL-BOWEL ULCER

Pathophysiological role of ion channels and transporters in gastrointestinal mucosal diseases

The incidence of gastrointestinal (GI) mucosal diseases, including various types of gastritis, ulcers, inflammatory bowel disease and GI cancer, is increasing. Therefore, it is necessary to identify new therapeutic targets. Ion channels/transporters are located on cell membranes, and tight junctions (TJs) affect acid–base balance, the mucus layer, permeability, the microbiota and mucosal blood flow, which are essential for maintaining GI mucosal integrity. As ion channel/transporter dysfunction results in various GI mucosal diseases, this review focuses on understanding the contribution of ion channels/transporters to protecting the GI mucosal barrier and the relationship between GI mucosal disease and ion channels/transporters, including Cl⁻/HCO₃⁻ exchangers, Cl⁻ channels, aquaporins, Na⁺/H⁺ exchangers, and K⁺ channels. Here, we provide novel prospects for the treatment of GI mucosal diseases.

Potassium Channelopathies and Gastrointestinal Ulceration

Potassium channels and transporters maintain potassium homeostasis and play significant roles in several different biological actions via potassium ion regulation. In previous decades, the key revelations that potassium channels and transporters are involved in the production of gastric acid and the regulation of secretion in the stomach have been recognized. Drugs used to treat peptic ulceration are often potassium transporter inhibitors. It has also been reported that potassium channels are involved in ulcerative colitis. Direct toxicity to the intestines from nonsteroidal anti-inflammatory drugs has been associated with altered potassium channel activities. Several reports have indicated that the long-term use of the antianginal drug Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, increases the chances of ulceration and perforation from the oral to anal regions throughout the gastrointestinal (GI) tract. Several of these drug features provide further insights into the role of potassium channels in the occurrence of ulceration in the GI tract. The purpose of this review is to investigate whether potassium channelopathies are involved in the mechanisms responsible for ulceration that occurs throughout the GI tract.

Effect of potassium-magnesium citrate on upper gastrointestinal mucosa

BACKGROUND

Potassium supplements may cause mucosal damage of the gastrointestinal tract.

AIM

To evaluate the effect of a new potassium supplement, potassium-magnesium citrate (K-Mag), on upper gastrointestinal mucosa and to compare it with an older potassium supplement, potassium citrate (Urocit-K).

METHODS

A randomized and double-blind study was conducted utilizing 36 healthy adults. Subjects were randomized into three groups: K-Mag (70 mmol/day K, 35 mmol/day citrate and 17.6 mmol/day Mg); Urocit-K (70 mmol/day K and 23.4 mmol/day citrate), and placebo. All subjects took 5 tablets b.d. of the allocated drug and 2 mg t.d.s. of glycopyrrolate for 7 days. On day 8, stool was examined for occult blood, a symptom score was calculated and an oesophagogastroduodenoscopy was performed. Mucosal lesions were scored at five anatomic sites.

RESULTS

Demographic characteristics and symptom score were similar in the three groups (< 10% with more than mild symptoms). There were no significant differences in the endoscopic scores at any site examined nor in the total scores among the three groups. Erosion or ulcers were found in 180% of K-Mag, 23% of Urocit-K and 17% of the placebo group.

CONCLUSION

Short-term use of K-Mag does not appear to induce lesions in the upper gastrointestinal mucosa and its oral tolerance is similar to Urocit-K or placebo.

Pathophysiology of mesenteric ischemia

Intestinal ischemia can result from a host of pathophysiologic disturbances and, in turn, may produce a variety of adverse local and systemic consequences. Mechanisms of ischemic injury and the central role of vasoconstriction are discussed.

Diaphragm disease: pathology of disease of the small intestine induced by non-steroidal anti-inflammatory drugs

Operative small bowel resection specimens received over a period of 16 years were reviewed to assess whether any intestinal disease could be directly attributed to the use of non-steroidal anti-inflammatory drugs (NSAID). Seven cases of intestinal disease associated with the use of NSAID were identified, all of which occurred in the final six years of the survey, which may reflect the increasing use of these compounds. A spectrum of patterns was found from multiple pathognomonic ileal mucosal diaphragms to broad strictures similar to those seen as a complication of enteric potassium. It seems likely that the formation of diaphragm lesions requires an additional factor, but what is not known as yet is whether the effects of NSAID are local or systemic.

Clinicopathological features of nonsteroidal antiinflammatory drug-induced small intestinal strictures

The clinicopathological features in 4 patients are described where nonsteroidal antiinflammatory drugs appear to have caused small intestinal strictures. Two patients had rheumatoid arthritis and 2 patients had osteoarthritis; all had received nonsteroidal antiinflammatory drugs for 1.5-30 yr. Three patients had an initial illness characterized by diarrhea, profound weight loss, and hypoalbuminemia. Intestinal radiology at this stage ranged from subtle changes to those of Crohn's disease. Three patients underwent surgery. At operation the bland external appearance contrasted with the striking mucosal appearances of multiple concentric, circumferential, diaphragmatic strictures that caused luminal stenosis to a pinhole. These septa were due to submucosal fibrosis and the histopathological picture appears to represent a new nosological entity.

Nonspecific small bowel ulceration

Six patients (4 male, 2 female) developed nonspecific small bowel ulceration between the ages of 4 months and 76 y. Five had gastrointestinal haemorrhage, usually chronic and resulting in iron deficiency anaemia. Four had features of subacute intestinal obstruction; there were no perforations. A small bowel enema was the most useful single investigation for delineating the lesions, and surgical excision was curative in all but one case. No aetiological causes could be implicated, other than in one patient taking a daily tablet of Navidrex-K.

Clinicopathologic study of nonspecific ulcers of the small intestine

Fifty-nine cases (31 men and 28 women) of nonspecific small bowel ulceration, representing the Mayo Clinic experience from 1956 to 1979, are reviewed. The average age was 51 years. Presenting symptoms or signs were those of intermittent small bowel obstruction (63%), blood loss (25%), and acute abdomen (12%). Whereas 78% of the ulcers were located in the ileum, 15% in the jejunum, and 7% in the jejunoileum, perforation was by far more common in the jejunum (78%) as compared with the ileum (11%). Diagnosis was rarely made preoperatively, although abnormalities were noted roentgenographically in 66%. Treatment was surgical and was usually curative. Operative mortality was 8.5%. No single cause was implicated.

Idiopathic and drug-induced ulceration of the small intestine

Ulceration of the small intestine is an uncommon lesion of multifactorial origin. The most important factor responsible for the reported increased incidence is the ingestion of enteric-coated potassium chloride. It is desirable that potassium supplements be given in another form, for example as a slow-release preparation. Other drugs which may play a part in the aetiology include corticosteroids and phenylbutazone.

Diagnosis is difficult and ulceration is usually only demonstrated after one of the complications (obstruction, perforation, or haemorrhage) has occurred. It is imperative that a full drug-taking history is obtained.

Laboratory tests are not helpful in diagnosis, but where radiological studies are carried out they often contribute useful information.

If the symptoms of such an ulcer are severe enough to warrant laparotomy, then the treatment of choice is excision of the affected segment followed by end-to-end anastomosis.

Circumferential small bowel ulcers: a report of nine cases

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