Adenosine deaminase and carcinoembryonic antigen in pericardial effusion diagnosis, especially in suspected tuberculous pericarditis

BACKGROUND

Adenosine deaminase (ADA) and carcinoembryonic antigen (CEA) have been measured in pleural fluid to help distinguish malignant from benign effusions, especially in tuberculous pleurisy. We investigated ADA and CEA levels in patients with moderate to large pericardial effusions of different etiologies.

METHODS AND RESULTS

We performed diagnostic and therapeutic pericardiostomy with drainage and biopsy. We measured ADA and CEA levels in the pericardial fluid in 26 patients with moderate to large pericardial effusion and 19 control patients. Patients were included in a prospective protocol from August 1991 to August 1993. Patients were grouped as follows: group 1, 9 patients with tuberculous pericarditis (TP) confirmed by bacteriologic culture or histology of pericardial biopsy; group 2, 5 patients with clinically strongly suspected TP; group 3, 12 patients with malignancy (8) and acute pericarditis (4); group 4, 19 control patients without pericardial disease. We treated patients with TP with isoniazid, rifampin, and either streptomycin or ethambutol for 12 months and pyrazinamide for 2 months. We observed for symptoms and signs of recurrent pericarditis or constrictive pericarditis on follow-up. In group 1 the ADA activity was significantly higher (101 +/- 14 U/L) than that in group 3 (22 +/- 5 U/L) or that in group 4 (17 +/- 2 U/L) (P < .05). There was no significant difference between ADA activity in group 1 (101 +/- 14 U/L) and that in group 2 (100 +/- 26 U/L). With a cutoff value for ADA activity of 40 U/L, sensitivity was 93% and specificity 97% in the diagnosis of TP. In benign diseases, the CEA level was significantly lower (1.0 +/- 0.3 ng/mL) than that in malignant diseases (135.1 +/- 79.7 ng/mL) (P < .05). With a cutoff value for CEA level of 5 ng/mL, sensitivity was 75% and specificity 100% in the diagnosis of malignant pericarditis. Follow-up study (mean, 12.9, 19.8, and 11.8 months in groups 1, 2, and 3, respectively, showed no symptoms or signs of constrictive pericarditis, except for 1 patient.

CONCLUSIONS

Pericardial fluid ADA and CEA are useful for the differential diagnosis of pericardial effusion of various causes. They also have great value in early diagnosis of TP, particularly when the results of other clinical and laboratory tests are negative.

The intraperitoneal effects of 5-hydroxytryptamine on haemodynamics, gastric mucosal blood flow and platelet aggregation

The effects of 5-hydroxytryptamine (5-HT) on gastric mucosal blood flow and lesion formation have been established. However, the mechanisms accounting for the reduction of gastric mucosal blood flow have not been defined. The current study aimed to test the hypothesis that decrease of gastric mucosal blood flow in rats is the result of changes of systemic blood pressure and/or platelet aggregation. 5-HT (given i.p. 5 or 10 mg/kg) time and dose dependently reduced gastric mucosal blood flow and systemic arterial blood pressure; it also potentiated ethanol-induced mucosal damage. Methysergide (a 5-HT2-receptor blocker) pretreatment alleviated the decrease of gastric mucosal blood flow and lesion formation but not the systemic blood pressure. Also in the 5-HT-treated animals, the mucosal oxygen (O2) and haemoglobin levels as well as the systemic blood CO2 were reduced, but the blood O2 was increased. The latter two parameters correlated with an elevation of the respiratory rate. The blood platelet count was not affected by 5-HT pretreatment. Adenosine diphosphate (ADP) dose dependently induced a similar degree of platelet aggregation in platelet rich plasma fractions in the saline and 5-HT-treated rats in vitro. 5-HT in the concentrations of 1 or 10 microM, promoted the platelet aggregation produced by ADP. However, this action was attenuated in the 5-HT-pretreated rats, indicating that tachyphylaxis of 5-HT action on platelet aggregation could occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of beta-adrenoceptor antagonists on portal vein hypertension and ethanol-induced gastric mucosal damage in rats

The effects of various beta-adrenoceptor antagonists, with different pharmacological properties, on systemic and portal vein blood pressure and on ethanol-induced gastric mucosal damage were examined in surgically-induced portal hypertensive rats. Propranolol (5, 10 or 20 mg kg-1), nadolol (5 or 10 mg kg-1), metoprolol (10 or 20 mg kg-1), labetalol (20 or 40 mg kg-1) and pindolol (3 or 6 mg kg-1) reduced systemic blood pressure to a similar degree in both portal vein-ligated and sham-operated rats. All beta-adrenoceptor antagonists, except for pindolol, significantly reduced portal venous pressure and ethanol-induced macroscopic gastric mucosal damage in portal hypertensive animals. Sham-operated rats had lower portal venous pressure and less gastric damage compared with portal hypertensive rats, but both were unaffected by beta-adrenoceptor antagonist pretreatment. We conclude that: propranolol, nadolol, metoprolol and labetalol are effective in reducing the portal venous pressure and ethanol-induced gastric mucosal damage in portal hypertensive rats, but not in portal normotensive animals; there was no direct relationship between the reduction of portal vein and systemic blood pressure; and local anaesthetic action is probably important in reducing the portal vein pressure and ethanol-induced gastric mucosal lesions, while the intrinsic sympathomimetic effect can counteract the actions of the beta-adrenoceptor antagonists on portal venous pressure and gastric mucosa.

The differential mechanisms of mild irritants on adaptive cytoprotection

The protective action of mild irritants has been established. However, the mechanisms as to how they antagonize the injurious action produced by the subsequent challenge with an ulcerogenic stimulus are still unclear. The present study examined the different protective mechanisms of an oral administration of the three mild irritants, 20% ethanol, 0.3 mol/L HCl or 5% NaCl against the gastric injurious actions of absolute ethanol in rats. In an attempt to clarify the pathways and mediators involved in the adaptive cytoprotection, [D-Pro2, D-Trp7,9]-substance P (substance P antagonist), Nw-nitro-L-arginine methyl ester (L-NAME), indomethacin, capsaicin, lidocaine, atropine or hexamethonium was given. The protective action of 20% ethanol but not the other two mild irritants, was antagonized by L-NAME, indomethacin and capsaicin, which are the inhibitors of nitric oxide (NO) and prostaglandins (PG) synthesis, and afferent sensory neuron blocker, respectively. Substance P antagonist, lidocaine or atropine given alone, prevented mucosal damage; however, only substance P antagonist enhanced the anti-lesion action of 20% ethanol, while atropine and lidocaine increased the protective effect of NaCl and HCl. The three mild irritants increased the residual gastric secretion. Only 20% ethanol and 5% NaCl but not 0.3% HCl significantly increased the basal adherent mucus and also attenuated the mucus depletion by absolute ethanol. It is concluded that the cytoprotective action of either ethanol or NaCl seems to be mediated through the increase of residual gastric secretion and adherent mucus. In the ethanol-treated group, these actions could act through the afferent sensory fibres, with NO and PG as the possible mediators.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of hemodynamic changes in rat stomachs by laser Doppler velocimetry and reflectance spectrophotometry. Effects of ethanol and prostaglandin E2 under ischemic and congestive conditions

One of the ulcerogenic mechanisms by which ethanol induces mucosal lesions in the stomach is the depression of gastric mucosal blood flow (GMBF). The goal of this study was to determine whether lesion formation is the result of vascular ischemia alone or ischemia combined with congestion. The aims of this study were to answer this question by evaluating the relationship between GMBF, oxygen saturation (ISO2) and hemoglobin volume (IHb) in the gastric mucosa under the influences of ethanol and prostaglandin E2 (PGE2) in the ischemic and congestive states, using a laser Doppler flowmeter and tissue spectrum analyzer. Ligation of the gastric celiac artery or vein markedly decreased the GMBF and the ISO2 level. The former procedure also reduced but the latter increased the IHb level. Ethanol administration produced effects similar to venous ligation, i.e. vascular stasis with ischemia. There was a negative correlation between GMBF and severity of lesion formation after ethanol administration. However, at the lesion site all the hemodynamic parameters were significantly reduced, indicating that a necrotic condition had occurred. PGE2 preincubation (25 micrograms) elevated GMBF, ISO2 and IHb levels. It also alleviated the reduction of blood flow induced by ethanol and increased the recovery rate of GMBF and ISO2 after the release of arterial or venous ligation. It is concluded that the decrease in blood flow due to ethanol is probably caused by constriction of venules rather than arterioles inside the mucosa, and this effect could lead to vascular congestion. PGE2 probably dilates both arterioles and venules in the gastric mucosa and thereby increases the blood flow in the gastric mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

The vagus nerve and its non-cholinergic mechanism in the modulation of ethanol-induced gastric mucosal damage in rats

The role of the cholinergic pathway in the vagus nerve in modulating gastric lesion formation by ethanol was examined, using an ex-vivo stomach chamber preparation. Subdiaphragmatic vagotomy significantly increased the lesion areas but lowered acid secretion and gastric mucosal blood flow (GMBF). Atropine had no effect, whereas pirenzepine antagonized ethanol-induced mucosal damage. All three procedures showed similar potencies in depressing acid secretion, but only pirenzepine reversed the fall in the GMBF produced by ethanol. These differential effects of vagotomy, atropine and pirenzepine on gastric function suggest that the cholinergic component in the vagus nerve may not be important in the formation of ethanol-induced gastric damage. The persistent protective action as well as the restoration of ethanol-induced GMBF drop by pirenzepine in vagotomized animals further support this hypothesis. The worsening effect of vagotomy is probably modulated by a non-cholinergic mechanism, the abolition of which makes the gastric mucosa more susceptible to damage by ethanol. The acid-independent protective action of pirenzepine and its influence on the GMBF, which were not exhibited by atropine, are indeed unique and perhaps may be attributed to this non-cholinergic pathway.

The role of endogenous ulcerogenic mediators in the pathogenesis of peptic ulcer

The pathogenetic mechanisms of different types of peptic ulcer are still unclear. Extensive investigations have been focused on the identification of potential endogenous ulcerogenic mediators in animals and men. These studies are important in the development of a better therapeutic agent, either to prevent or to cure peptic ulcer in humans. Several endogenous substances have been identified and are reported to be involved in the production of gastrointestinal lesions in animals. Also these substances were increased during inflammatory responses and their actions were reported as vascular dependent and possibly free radicals related. Reports related to the types of these mediators have been extensive. The more important ones include some of the lipid metabolites, neuropeptides, biogenic amines, and also Helicobacter pylori and reactive free radicals. The present study summarizes the ulcerogenic mechanisms of these substances and the types of ulcer involved. More current information may enable us to understand better the etiology of peptic ulcer and possibly its prevention and cure in man. Any particular types of ulceration will not be specifically discussed in this article, because they have been extensively studied and reviewed.

Influence of chronic nicotine intake and acute ethanol challenge on gastric mucus level and blood flow in rabbits

The effects of nicotine pretreatment on ethanol-induced gastric mucosal lesions and changes of gastric mucosal mucus levels and blood flow (GBF) were studied in anaesthetized rabbits. Nicotine treatment 25 or 50 micrograms/ml drinking water did not affect the volume of water consumption during the 10-day experimental period. It did not produce gastric mucosal lesions or affect the superficial adherent mucus content. The length of mucus-containing cells and the basal GBF were also unaffected. Intragastric administration of absolute ethanol reduced GBF, this effect was not altered by nicotine. However, the alkaloid potentiated the ulcerogenic actions of ethanol both on lesion formation and mucus depletion evoked by graded oral doses of ethanol (50 or 100%, v/v). Ultrastructurally, the mucous cells were more degenerated in the animals co-treated with nicotine and ethanol. It is concluded that reductions of mucus-containing cells and adherent mucus on the gastric mucosa are likely to be the contributory factors involved in the aggravating action of nicotine on ethanol-induced gastric mucosal lesions in rabbits.

Portal hypertension. Its effects on gastric function and ethanol-induced gastric mucosal damage in rats

The time-course effects of portal hypertension on gastric secretory function, mucosal blood flow, vascular permeability, and ethanol-induced gastric mucosal damage were examined in anesthetized rats. Partial ligation of the portal vein effectively produced portal hypertension one to three days later but the raised pressure returned to normal on the sixth day after ligation. This time-course effect coincided with reduced pepsin secretion and mucosal blood flow and also with potentiated ethanol-induced mucosal damage during the first to third days. These effects started to tail off on the sixth day. However, gastric acid output was significantly reduced on the third day, and this was strongest on the sixth day after operation. Portal vein ligation also reduced basal vascular permeability, which was markedly potentiated after ethanol treatment. It is concluded that: (1) portal vein blood pressure changes are a time-dependent process following ligation; (2) changes in gastric mucosal blood flow (GMBF) and lesion formation are closely related to portal hypertension; (3) gastric mucosal injury is associated with vascular damage, as evidenced by increased in vascular permeability; and (4) pepsin but not acid secretion is closely related to the state of the GMBF.

Role of gastric glandular mucosal energy metabolism in cold-restraint gastric lesion formation

The effects of cold and restraint and of some of the antiulcer drugs on adenosine nucleotide content in the gastric glandular mucosa were examined. A bioluminescence technique was used to measure the amount of ATP and its metabolites in gastric mucosal tissue. Cold-restraint produced gastric lesions and increased the gastric mucosal ATP. Verapamil pretreatment attenuated these lesions and further intensified the ATP increase in a dose-related manner. The ATP/ADP ratio and the Atkinson index were also elevated. Calcium gluconate produced similar effects. Atropine or EGTA pretreatment protected or worsened the gastric lesion, respectively, but did not have any influence on the changes in mucosal energy metabolism. Ranitidine pretreatment lessened the lesion formation but had no influence on the nucleotide content. These findings indicate that the metabolic rate of the gastric mucosa is suppressed during cold-restraint conditions; this depression is probably due to hypothermia and reduction of mucosal metabolism. The lesion-protecting mechanisms of the drugs do not seem to be mediated through their effects on mucosal energy metabolism. The oxygen- and ATP-sparing effects of verapamil may contribute partly to its gastro-protective effect.

Effect of epidermal growth factor on gastric blood flow in rats: possible role in mucosal protection

BACKGROUND

The mechanism by which epidermal growth factor (EGF) protects the gastric mucosa against injury is unclear. Whether EGF has any effect on gastric blood flow has not been reported.

METHODS

Using an ex vivo gastric chamber preparation, the effect of EGF on gastric blood flow in rats was studied by laser Doppler flowmetry. Measurements of blood flow and mucosal damage were made in both intact and sialoadenectomized rats with graded doses of EGF at basal condition and after topical application of absolute ethanol.

RESULTS

Sialoadenectomy alone increased ethanol-induced gastric mucosal lesions (P < 0.05) but had no significant effect on blood flow. EGF pretreatment resulted in both a reduction in ethanol-induced gastric mucosal injury as well as a significant increase in blood flow compared with controls (both P < 0.05). Graded doses of EGF (3.12-25 micrograms) resulted in an dose-dependent increase in gastric blood flow (r = 0.68; P < 0.001), which correlated inversely with the degree of mucosal damage (r = -0.72; P < 0.001).

CONCLUSIONS

Mucosal protection by EGF is accompanied by an increase in gastric blood flow; this action may contribute to its mucosal protective effect.

Adenosine and cholinergic-induced gastric contraction in rats

Adenosine is known for its modulatory effects on gastric secretory function and mucosal blood flow in rats. However, its action on gastric motility has not been defined. The influence of adenosine on gastric contractions provoked by cholinergic drugs and direct vagal stimulation have, therefore, been examined. Bethanechol (25, 50 or 100 micrograms/kg i.v.) and electrical vagal stimulation dose and voltage dependently increased the number and the amplitude of gastric contractions. An adenosine-A1-receptor agonist, L-phenylisopropyladenosine (10 or 50 micrograms/kg s.c.), given 30 min beforehand, did not affect the changes in gastric parameters but decreased the basal mean blood pressure and lessened the reduction in blood pressure evoked by bethanechol. The adenosine-A2-receptor agonist N-ethylcarboxaminoadenosine (1 or 5 micrograms/kg s.c.), 30 min beforehand, however, significantly increased the number but not the force of gastric contractions; a lower dose of this drug increased the basal blood pressure and potentiated the depressive action of bethanechol on systemic blood pressure. Adenosine administration (7.5 mg/kg s.c.) significantly increased its plasma levels at 30 and 60 min after injection; pretreatment with it (2.5, 7.5 or 12.5 mg/kg s.c.), 30 min beforehand, did not affect the gastric and vascular actions of bethanechol. The highest dose of adenosine potentiated the contractile response of vagal stimulation. In the isolated fundus preparation, adenosine added to the organ bath (10(-6), 10(-4), 10(-2) M) also did not affect the contractions induced by acetylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nicotine on activity and stress-induced gastric ulcers in rats

Nicotine is known to influence locomotor activity. The alkaloid also intensifies gastric ulcer formation in stressed rats. The effects of nicotine on locomotor activity in relation to gastric lesions induced by restraint at 4 degrees C for 2 h (stress) were, therefore, studied. Ten-day treatment with nicotine 25 or 50 micrograms/ml drinking water potentiated stress-evoked ulceration and mast cell degranulation. These same doses of nicotine increased vertical motor activity; only the higher dose of the alkaloid enhanced horizontal movements. Phenobarbitone (12.5, 25, or 50 mg/kg, SC) dose dependently reduced vertical activity, as well as stress-induced gastric ulceration and mucosal mast cell degranulation. The drug also lessened the potentiating effects of nicotine on motor activity and stress-evoked gastric lesion formation. It is concluded that the ability of chronic nicotine treatment to intensify stress-induced gastric ulceration most likely owes part of its action to a mechanism evoking increased activity, which possibly reflects an influence on the CNS, as well as to enhancement of mast cell degranulation in the stomach glandular mucosa.

Congenital absence of gallbladder

Nine surgically proven congenital absence of gallbladder (CAGB) cases were reviewed. All of them had one or more kinds of biliary symptom. Tests such as abdominal ultrasonography, intravenous or oral cholecystography and even endoscopic retrograde cholangiography not only failed to predict CAGB but misleadingly indicated other similar conditions. Only the abdominal computed tomography (CT), performed on one patient, enabled the accurate diagnosis of CAGB. All the patients underwent abdominal exploration, and CAGB was confirmed by the meticulous dissection of the entire extrahepatic biliary tree and the operative cholangiography. Five patients had concomitant biliary pathologies responsible for their symptoms, but four patients had isolated CAGB. CAGB is a rarely encountered condition for a clinician, but extensive diagnostic work-ups including abdominal CT should be performed in all situations where CAGB is suspected. Thus unnecessary exploration can be avoided in the isolated CAGB case.

A correlative study on serum cholylglycine levels in hepatobiliary disease

The serum cholylglycine (CG), alanine aminotransferase (ALT) and total bilirubin levels were studied in 210 patients with hepatobiliary disease and in 70 healthy subjects. Serum CG concentrations in all the hepatobiliary diseases were found to be significantly higher than those of their controls. Patients with abnormal increases in ALT and bilirubin levels also showed raised CG concentrations; however, some patients with normal ALT and bilirubin levels, still had markedly elevated CG values. Patients with hepatic cirrhosis had high serum CG levels, followed, in descending order, by chronic active hepatitis and chronic persistent hepatitis. In the cholecystitis and cholelithiasis cases, their CG levels were significantly higher than those of the controls but lower than the values in hepatic disease patients; however, more cholecystitis cases had abnormally high serum bilirubin levels than CG. The results also show that serum CG concentrations vary in the different hepatobiliary diseases, and that serial CG measurements are more sensitive than measuring ALT and bilirubin levels in the diagnosis of hepatic diseases. Serum CG can be used as an index for evaluating the activity of chronic hepatitis; it can also be employed as a diagnostic tool in cholecystitis and cholelithiasis.

The influence of chronic nicotine treatment on stress-induced gastric ulceration and emptying rate in rats

Ten-day treatment with nicotine (5, 25 or 50 micrograms/ml drinking water) dose-dependently intensified gastric ulceration induced by cold-restraint, and emptying rate. Stomach contractions produced by graded doses of bethanechol i.v. were elevated further by nicotine treatment. It is suggested that chronic nicotine administration produces hypersensitivity of the gastric muscarinic receptors; stomach hypermotility contributes to the ulcer-worsening action of the alkaloid.

Surgical intervention in patients with aplastic anemia

Eighteen surgical procedures have been performed on 14 cases of aplastic anemia (AA). Of the 10 major surgical procedures, 7 were emergency and 3 elective. The median duration from the diagnosis of AA to major surgery was 0.5 months (3 days-47.3 months), and the median survival after surgery was 12.3 months (4 days-38 months). The hematological status of AA at the time of major surgery were 3 in partial response (PR), 2 with no response (NR) and 5 at diagnosis, respectively; and those after major surgery were 2 with complete response (CR), 2 in PR, 1 with minimal response, and 2 in NR. Three postoperative complications were sepsis, pneumonia and atelectasis encountered in 2 cases. A total of 3 deaths were caused by infection and cancers. Considering the fact that surgery may not only control complications, but offer the opportunity to give effective therapy for AA and therefore improves chances for survival, it is strongly suggested that active surgical intervention should be performed if the patient's status is not terminal.

Chronic nicotine intake increases the responses to muscarinic receptor stimulation

Chronic nicotine administration depresses the autonomic ganglia, but its effects on the muscarinic receptors at the neuroeffector sites remain unclear. The present study, using rats, examines the influence of chronic treatment with nicotine (25 micrograms/ml drinking water) for 10 or 15 days on muscarinic receptor responses, as reflected by bethanechol-evoked gastric secretion or by acetylcholine-induced decreases in mean blood pressure. Bethanechol, 0.4, 0.8, 1.6 or 3.2 mg/kg injected subcutaneously, dose-dependently increased the basal gastric secretory volume and acid output in pylorus-ligated control animals which normally drank tap water. Rats given nicotine in their drinking water for 10 or 15 days showed a further marked increase in both the volume of gastric secretion and acid output in response to bethanechol injections. Although bethanechol dose-dependently increased acid secretion, the ulcer index was very small and there was no significant difference between the control and nicotine-treated groups. The basal mean blood pressure remained normal after the 10-day nicotine treatment. Acetylcholine, 0.1, 0.3, 1 or 3 micrograms/kg given intravenously, decreased the mean blood pressure; this acetylcholine-evoked blood pressure fall was intensified by nicotine pretreatment. The findings suggest that the responses to muscarinic receptor stimulation are increased by chronic nicotine treatment for 10 or 15 days. These exaggerated effects are possibly the consequence of persistent autonomic ganglion blockade by chronic nicotine treatment.

Natural killer activity and antibody-dependent cellular cytotoxicity in patients with primary lung cancer

The NK activity and ADCC of peripheral blood mononuclear cell were examined to evaluate the contribution of ADCC and NK activity to host immune response against lung cancer. The NK activity and ADCC were examined in 58 patients with primary lung cancer and 40 healthy volunteers as normal controls. The NK activity of patients with lung cancer was significantly subnormal, but ADCC was at a normal level. The NK activity was decreased in non-small cell lung cancer (NSCLC), but not in small cell lung cancer (SCLC) compared to normal controls. According to stage, the NK activity in stage II, III-M0 and III-M1 NSCLC showed low levels compared to that of stage I NSCLC, but there was no difference of NK activity in patients with SCLC. The NK activity was not affected by performance status. There was no significant difference of ADCC in patients with lung cancer according to cell type, stage and performance compared with that of normal controls. The NK activity and ADCC were not changed after chemotherapy and operation respectively.

The role of the vagus nerve in the protective action of acid inhibitors on ethanol-induced gastric mucosal damage in rats

The role of vagus in the actions of different acid inhibitors on ethanol-induced gastric damage and mucosal blood flow (GMBF) changes was studied in anaesthetized rats, using an ex vivo stomach chamber preparation. Subdiaphragmatic bilateral vagotomy decreased the basal gastric acid secretion and GMBF; it also intensified ethanol-evoked lesions in the glandular mucosa. Misoprostol, omeprazole and cimetidine produced a similar degree of reduction in acid output. Misoprostol given subcutaneously (s.c.) (50 micrograms/kg), or added to the incubation solution (12.5 micrograms) for 15 min, markedly prevented ethanol-induced lesion formation and reduction in GMBF. The reversing effect of s.c. injection of misoprostol on either lesion formation or on GMBF reduction was attenuated by vagotomy. Omeprazole protected against lesion formation only when present in the incubation solution (12.5 mg) of ex vivo chamber preparations of both vagus-intact and vagotomized animals, but the effect was significantly less in the latter group. The drug also prevented the depressive action of ethanol in vagus-intact animals. Cimetidine pretreatment (50 mg s.c. or 12.5 mg in incubation solution), however, did not modify the effects of ethanol on lesion formation and the GMBF. The findings indicate that the three different types of acid inhibitors exert different actions on ethanol-induced gastric mucosal damage, although they produced similar inhibition of acid output. Vagotomy lowers the GMBF and attenuates the antiulcer action of misoprostol and omeprazole, especially when the drugs are given by the parenteral route.

Adenosine: a novel ulcer modulator in stomachs

Adenosine has been demonstrated for its actions on gastric secretion and stress-induced gastric ulceration in animals. We examined the pharmacological actions of adenosine on ethanol-evoked gastric lesions and gastric mucosal blood flow (GMBF) in rats, because both of them are closely related. Adenosine pretreatment, in dose of 7.5 mg/kg increased GMBF and protected against ethanol-evoked gastric lesion formation. However, this antiulcer action was followed by an aggravation of gastric lesions and reduction in GMBF. We further investigated whether these actions could act through the adenosine A1 or A2 receptors, therefore L-phenylisopropyladenosine (L-PIA) or N-ethylcarboxamidoadenosine (NECA), the adenosine A1 or A2 receptor agonists, respectively, were used. The drugs given in doses of 10 or 50 micrograms/kg for L-PIA and 1 or 5 micrograms/kg for NECA, dose-dependently inhibited GMBF and potentiated ethanol-induced gastric damage. When the two drugs were given together to animals, they did not further aggravate the severity of ulceration and reduction of GMBF. These findings indicate that the antiulcer action of adenosine is not mediated via the adenosine A1 and A2 receptors but if acts through different adenosine receptor subtypes. It was because the lesion worsening effects of adenosine at the second stage of the biphasic responses were similar to the actions of L-PIA and NECA, the ulcer potentiating effect is probably acting through adenosine A1 and A2 receptors in anaesthetised rats.

Ethanol and the antioxidant defense in the gastrointestinal tract

Ethanol is known to have profound actions on the gastrointestinal tract. The present study was undertaken to examine the effects of ethanol on some of the natural antioxidant defensive enzymes in the gastrointestinal tract; the activities of these enzymes in the liver and the brain were also measured for comparison with those in the gastrointestinal tract. Oral administration of absolute ethanol induced severe gastric mucosal lesions and also damage in the small intestine, however the total superoxide dismutase was unaffected in the tissues measured. The glucose-6-phosphate dehydrogenase activity was reduced only in the stomach while the total glutathione was elevated in the small intestinal mucosa. The catalase activities were activated in the stomach, small and large intestines, and brain, but not in the liver which contained the highest concentration of the enzyme. The present findings indicate that endogenous hydrogen peroxide may be an important damaging agent towards biomolecules in different organs and the removal of this by catalase represents an important defensive mechanism against ethanol toxicity.

The inhibitory action of ethanol on the gastric mucosa and its interaction with the vagus in rats

The influence of systemic ethanol and/or the vagus on ionic secretion and on glandular mucosal blood flow (GMBF) was studied in an ex-vivo gastric chamber preparation in rats. Sub-diaphragmatic vagotomy decreased H+ secretion and Na+ outflux from the gastric mucosa. Subcutaneous injection of 50% ethanol significantly potentiated these responses, but not the concentrations of 25% and 100%. The three doses of ethanol did not affect the secretion of both H+ and Na+ in vagus-intact animals. Ethanol, however dose-dependently reduced the GMBF in both vagus-intact and sub-diaphragmatic vagotomised rats, and the effect was greater in the latter-operated animals. It is concluded that vagus nerves greatly influence the secretion of both H+ and Na+ the gastric mucosa but the effect is unrelated to GMBF. Systemic ethanol reduced the secretion of these ions only in vagotomised animals, indicating the vagus could play a role in modulating the action of ethanol in the stomach.