No abstract

This study's purpose was to determine whether portal hypertension adversely affects small intestinal mucosal injury. Portal hypertension was produced in male Sprague-Dawley rats by two-stage ligation of the portal vein. Sham-operated rats were used as controls. Two weeks later, intestinal injury was produced by in vivo perfusion with 5 mM chenodeoxycholic acid for 30 min. Intestinal injury was assessed by quantitative morphometry and by measuring intestinal water and mannitol absorption. Portal hypertension resulted in more injury in the distal perfused intestine as manifested by increased villus tip denudation [portal hypertensive 52.5 +/- 9.6 (SEM) vs controls 28.1 +/- 5.7 microns, P = 0.05). Additionally there was a significant decrease in the unperfused duodenal villus height in portal hypertensive rats (portal hypertensive 755 +/- 22 vs controls 848 +/- 28 microns, P less than 0.02). Portal hypertension had no significant effect on the increase in mannitol absorption or water secretion caused by chenodeoxycholic acid perfusion. This study suggests that portal hypertension alters small intestinal mucosa and increases susceptibility to injury.

To test whether omeprazole would increase the susceptibility of the duodenum to damage, 200 to 250-g male Sprague-Dawley rats were given 10 mg/kg of omeprazole (Losec) by gavage every morning for 29 days. Control rats were given gavage buffer alone. After fasting overnight, half the rats received 10 mg/kg indomethacin intraperitoneally; then all rats were given 2 ml of 50% ethanol by gavage. Three hours later the rats were killed and the stomach and duodenum removed and histologic injury to the duodenal mucosal was quantitated. In omeprazole pretreated rats, gavage with ethanol resulted in a significant twofold worsening of duodenal injury. Pretreatment with indomethacin to decrease endogenous prostaglandin production resulted in more severe ethanol-induced duodenal injury in both groups; however, there were no longer statistically significant differences between the omeprazole and control groups. Measurement of duodenal mucosal synthesis of prostaglandin E2 showed no difference between the omeprazole and control groups. Thus chronic administration of omeprazole appears to increase the susceptibility of the duodenal mucosa to ethanol injury in rats. The mechanism of this effect is as yet unknown but does not appear to be prostaglandin-mediated.

The atrial natriuretic peptide hormonal system is altered to a variable degree in patients with cirrhosis. Portal pressure and portal-systemic shunting are also varied in cirrhosis. We used a portal vein-ligated rat model with predictable portal hypertension to study the effects of portal hypertension alone on the atrial natriuretic peptide hormonal system. Sham-operated rats were used as controls. Mean portal pressure was significantly increased in portal vein-ligated rats (portal vein-ligated rats, 21.7 +/- 0.74 cm H2O; sham-operated rats, 13.7 +/- 0.47 cm H2O; p less than 0.0001). Plasma atrial natriuretic peptide decreased 50% in the portal vein-ligated rats (p less than 0.0001). Atrial natriuretic peptide messenger RNA level was decreased by 40% to 60% in the left and right atria and in the ventricles of portal vein-ligated rats (p less than 0.05 for each chamber). Only one class of glomerular binding site was identified by competitive binding studies. The atrial natriuretic peptide glomerular receptor density increased in the portal vein-ligated rats (portal vein-ligated rats, 1,660 +/- 393; sham-operated 725 +/- 147 fmol/mg protein, p less than 0.02), whereas affinity decreased (portal vein-ligated, 1.69 +/- 0.49; sham-operated, 0.55 +/- 0.12 nmol/L, p less than 0.02). No difference was seen in the amount of cyclic GMP generated by atrial natriuretic peptide stimulation in isolated glomeruli from portal vein-ligated and sham-operated rats.(ABSTRACT TRUNCATED AT 250 WORDS)