Role of taurocholic acid in production of gastric mucosal damage after ingestion of aspirin

Gastric potential difference as a model in clinical pharmacology: assessment of gastric mucosal response to aspirin

Gastric potential difference in 16 healthy subjects (GPD) was measured on three different days to assess baseline variability. The effect of three different doses of aspirin on PD in 19 additional subjects was determined. Several new parameters are suggested for better description of the GPD changes following ingestion of known gastric irritants. From these parameters, a Reiz Index (RI) was calculated as a single term representing the extent and severity of the GPD response to aspirin. One-way Anova followed by Scheffe comparisons showed significant differences between the mean RI values resulting from the administration of aspirin 250, 500 and 1000 mg.

Changes in potential difference across the human buccal mucosa with buffered or unbuffered aspirin and salicylate

The potential difference (PD) across the gastric mucosa is an index of mucosal integrity, and is lowered by topical application of irritants such as aspirin. There are basic similarities in the PD across the buccal and gastric mucosae, and we have therefore investigated the actions of various salicylates in buffered or un-buffered solution on buccal PD in human subjects. Aspirin (at pH 2) and soluble aspirin (pH 4.4) applied topically reduced buccal PD, but this fall was abolished by buffering to pH 7. Sodium salicylate likewise reduced buccal PD at pH 4 and pH 6, but not when buffered to pH 7. Two other soluble aspirin mixtures also reduced buccal PD, indicating insufficient buffering capacity to prevent topical irritancy. Ingestion of aspirin (600 mg), avoiding topical contact with the buccal mucosa, did not alter buccal PD. Paracetamol applied topically likewise failed to reduce buccal PD. Measurement of buccal PD may be useful in the preliminary assessment of the gastrointestinal irritation provoked by anti-inflammatory and other compounds.

The effect of antacids on the occurrence of bile acid and aspirin-induced gastric lesions in rats

Taurodeoxycholic acid increases the incidence of aspirin induced gastric bleeding in rats and in vitro is well bound by Aludrox (aluminium hydroxide) and poorly bound by Maalox (aluminium hydroxide and magnesium hydroxide). We studied the relevance of this binding, as demonstrated in vitro, by observing the effect of the antacids on the occurrence of taurodeoxycholic acid and aspirin-induced bleeding in vivo in rats. Six groups of fasting male Sprague-Dawley rats (n = 24) were intubated and given either water, Aludrox or Maalox and, 30 min later, aspirin or aspirin plus taurodeoxycholic acid. 4 h later the stomachs were examined and rats were scored positive if a lesion greater than 1 mm across was found (incidence of bleeding); a lesion scoring system was also used (severity of bleeding). The incidence of bleeding was increased from 63% with aspirin to 92% with aspirin plus taurodeoxycholic acid (P less than 0.05). The incidence was reduced to 33% and 67% respectively by Aludrox and to 29% (P less than 0.05) and 71% by Maalox. The severity of bleeding (median lesion score, quartiles in parentheses) was increased from 3 (1;6.5) (aspirin) to 10.5 (6;15) (aspirin plus taurodeoxycholic acid); P less than 0.001. These were reduced to 0.5 (0;3); P less than 0.02 and 5 (0.5;9.5); P less than 0.05 respectively by Aludrox and to 0 (0;3); P less than 0.02 and 3 (2;8); P less than 0.02 by Maalox. The severity of bleeding was reduced by both antacids but the effect appeared to be mainly on the aspirin rather than the bile acid component of the damage.

The effect of the synthetic prostaglandin analog 15 (R) 15 methyl-PGE2 methyl ester on gastric mucosal hemorrhage induced in rats by taurocholic acid and hydrochloric acid

The incidence of mucosal hemorrhage induced in rats by the oral administration of taurocholic acid (TCA) and hydrochloric acid (HCl) both singly and in combination was investigated. The effect of prostaglandin 15 (R) 15 methyl-PGE2 methyl ester (Me-PGE2) on the occurrence of hemorrhage induced by TCA with HCl was also studied. The incidence of hemorrhage induced by TCA (10 mM) alone and HCl (160 mM) alone was minimal and not different from that induced by the control solution. The combination of TCA (10 mM) and HCl (160 mM) produced bleeding in 67.7% of animals. The addition of 15 (R) 15 methyl-PGE2 methyl ester (9.9 micronM, corresponding to 50 microng/Kg) significantly reduced the incidence of hemorrhage induced by the combination of TCA with HCl from 67.7% to 31.3%. This suggests that this synthetic prostaglandin may be of value in conditions thought to be associated with reflux of bile into the stomach.

Gastric mucosal damage caused by plain and microencapsulated acetylsalicylic acid tablets in healthy subjects: a gastrocamera study

In a randomized, cross-over study plain acetylsalicylic acid (ASA) tablet and microencapsulated ASA tablets were given in doses of 1 gram 3 times a day for 3 days to 8 healthy subjects with no previous gastrointestinal disturbances. Gastrocamera examinations were performed before the ASA treatment and 1--2 hours after the last dose of ASA. The gastric mucosa appeared macroscopically normal at all the control examinations; whereas musocal bleeding was evident in all the subjects after the ASA treatment. There was no statistically significant difference between the plain ASA and the microencapsulated ASA preparations. No correlation could be found between the ASA concentration in plasma and the gastric mucosal damage.

Effect of prostaglandin 15(R) 15 methyl-E2 methyl ester on aspirin and taurocholic acid-induced gastric mucosal haemorrhage in rats

The effect of orally administered prostaglandin 15(R)15 methyl-E2 methyl ester on aspirin and taurocholic acid-induced gastric mucosal haemorrhage has been studied in rats. The incidence of haemorrhage induced by aspirin (26-7 mM), 64 mg/kg, together with taurocholic acid (2-5 mM), was significantly reduced from 53-6% to 19-5% by the addition of the prostaglandin (9-9 muM), P less than 0.01. The incidence of haemorrhage induced by aspirin alone (53-3 mM), 128 mg/kg, was significantly reduced from 80% to 20% by the addition of prostaglandin (9-9 muM), P less than 0.002. These results indicate the possible use of synthetic prostaglandins in the prevention of aspirin-induced gastric pathology.