Effects of pancreatic duct ligation and aging on acute taurocholate-induced pancreatitis. Experiments in the perfused pancreas in rats

CONCLUSION

When taurocholate was injected into the common bile duct, high ductal pressure due to ligation of the pancreatic duct did not produce more damage in the pancreas of both old rats and young adult rats, and levels of pancreatic enzymes in portal venous effluent were lower in old rats than in younger rats.

BACKGROUND

The effects of ligation of the pancreatic duct and aging on acute pancreatitis caused by taurocholate are still unclear.

METHODS

Young adult and old male Wistar rats were used. Six hours after ligation of the common bile duct in both the duodenum and liver hilus, rats were killed and the pancreata were perfused. Taurocholate or normal saline was injected retrogradely into the common bile duct. The levels of amylase and lipase in the portal venous effluent were determined as markers of damage to the pancreas. The pancreas was also histologically examined after the perfusion experiments using an Image Analysis System.

RESULTS

(1) A nonsignificant elevation of pancreatic enzymes was found in portal venous effluent by the retrograde injection of saline into the common bile duct. Injection of taurocholate caused a marked elevation of enzymes in the effluent for the first 30 min after injection, which then gradually decreased. (2) Basal levels of pancreatic enzymes were significantly higher in the ligation group than in the nonligation group. Injection of saline into the common bile duct had no apparent effect on enzymes in the effluent. In contrast, taurocholate injection into the common bile duct produced a marked increase in enzymes in the portal venous effluent. However, no significant difference was found between the ligation group and the nonligation group. (3) Similar findings were obtained when old rats were used. (4) Although basal levels of enzymes were almost the same in nonligated old and young adults rats, taurocholate injection into the pancreatic duct in old rats resulted in a significant depression of enzymes compared to that in young adult rats. In the ligation group, pancreatic enzymes in the portal venous effluent following taurocholate injection tended to be lower in old rats than in young adult rats. The results were histologically supported in that various degrees of fibrosis were found in the pancreata of old rats.

Dissociation of CCK-8-induced fluid secretion from protein secretion by ion-transport blockers in rat pancreas

The effects of ion-transport blockers on CCK-8-induced protein output and concomitant fluid secretion were compared in isolated, perfused normal and hypertrophied rat pancreata. In the normal pancreas, perfusion with ouabain (1 mM), amiloride (1 mM), furosemide (1 mM), or SITS (0.1 mM) caused corresponding inhibition of both fluid and protein secretion that was induced by 100 pM CCK-8. Hypertrophy of the pancreas was produced by oral administration of a synthetic protease inhibitor (FOY-305) once a day for 3 wk. In the hypertrophied pancreas, perfusion with ouabain (0.1 or 1 mM) or amiloride (0.1 mM or 1 mM) decreased CCK-8-induced fluid secretion without changing CCK-8-induced protein output. Perfusion with furosemide (1 mM) inhibited both fluid and protein secretion induced by CCK-8, but the amount of inhibition of fluid secretion was much greater than that of protein secretion. Perfusion with SITS (0.1 mM) significantly decreased CCK-8-induced fluid secretion but not protein secretion. These results indicate that in contrast to a normal rat pancreas, the coupling of fluid and protein secretion induced by CCK-8 can be disrupted by experimental procedures that induce hypertrophy in the rat pancreas.

Elevation of resting fluid secretion precedes trophic responses in the rat pancreas following a single oral administration of Camostat

A single dose of the synthetic proteinase inhibitor, Camostat (FOY-305; 100 mg/kg), was administered orally to rats. Pancreata were isolated and then perfused to examine the change in the level of resting fluid secretion. As early as 6 h after administration of the single dose of Camostat, the resting fluid secretion was significantly elevated. Twelve hours after administration, resting fluid secretion was maximally elevated, whereas contents of trypsinogen, chymotrypsinogen, and amylase per DNA in the pancreas were significantly decreased. After 12 h, the level of resting fluid secretion gradually decreased to the control resting level in contrast to significant increases in contents of the pancreatic enzyme and zymogens, and wet weight in acinar cells. We further examined the mechanism mediating the elevated resting fluid secretion. Our results are compatible with the view that the elevation of resting fluid secretion may be maintained by spontaneous activation of ion transporters: an ouabain-sensitive Na-K ATPase, an amiloride-sensitive Na-H antiporter, and a unique Cl transporter that is insensitive to furosemide, bumetanide, SITS, and DNDS.