Activation of alpha-amylase in urine

Cytokine Suppressive Agent Prevents Pancreatic Injuries Induced by Ischemia-Reperfusion in Rats

This study was designed to evaluate the possible role of cytokines (IL-1 and TNF-alpha) in the pathogenesis of pancreatic injuries induced by pancreatic ischemia-reperfusion and to evaluate the protective effect of the cytokine suppressive agent, FR167653, against pancreatic injuries. Pancreatic ischemia-reperfusion was induced in rats by ligating the celiac and caudate mesenteric arteries by small metallic clips for 45 min, after this ischemia, the metal clips were removed. Four hours after removing the metal clips, the animals were used for the experiments. In this model, mild hyperamylsemia and significant increases in pancreatic water and trypsin content were observed. Significant increases in serum IL-1 and TNF-alpha were also observed, as compared with the control rats. Pancreatic subcellular redistribution of lysosomal enzyme cathepsin B from the lysosomal fraction to the zymogen fraction was also observed. However, treatment with FR167653 at a dose of 0.5 mg/kg.hr significantly prevented all these pancreatic injuries. These results indicate that cytokines such as IL-1 and TNF-alpha might be involved in the pathogenesis of pancreatic injuries induced by ischemia-reperfusion, and that a cytokine suppressive agent might be of therapeutic value for the treatment of pancreatic ischemia.

Glucagon ameliorates pancreatic subcellular redistribution of lysosomal enzyme in rats with acute pancreatitis of closed duodenal loop

The protective effects of glucagon on the exocrine pancreas were investigated in rats with a closed duodenal loop (CDL). A CDL in rats caused marked hyperamylasemia, pancreatic edema and pancreatic histological damage such as acinar cell vacuolization and interstitial edema. A CDL also caused redistribution of the lysosomal enzyme, cathepsin B, from the lysosomal fraction to the zymogen fraction as well as the activation of trypsinogen in pancreatic tissue. Moreover, a CDL caused a marked motality rate (40% at 48 h). However, treatment with glucagon at a dose of 1.0 mg/kg (subcutaneous injection) every 8 h (3 times) significantly inhibited these pancreatic injuries, improving the survival rate (95% at 48 h). These results indicate the important role of lysosomal enzymes in the pathogenesis of severe acute pancreatitis, and also suggest the possible usefulness of glucagon in the treatment of clinical pancreatitis.

Peptide leukotriene receptor antagonist diminishes pancreatic edema formation in rats with cerulein-induced acute pancreatitis

BACKGROUND

This study was designed to evaluate the protective effect of a peptide leukotriene receptor antagonist, pranlukast hydrate, against pancreatic injuries during acute pancreatitis.

METHODS

Acute pancreatitis was induced in rats by intravenous infusion of a supramaximal dose of cerulein (5 micrograms/kg h for 4 h). In this model marked hyperamylasemia, a significant increase in pancreatic water content, and a significant increase in pancreatic microvascular leakage of Evans blue dye were observed. Pancreatic subcellular redistribution of the lysosomal enzyme cathepsin B from the lysosomal fraction to the zymogen fraction was also observed.

RESULTS

Pretreatment with pranlukast hydrate at a dose of 10 micrograms/kg (twice, 8 and 4 h before cerulein infusion) significantly inhibited these pancreatic injuries, including hyperamylasemia, increased pancreatic microvascular permeability, and redistribution of cathepsin B in pancreatic acinar cells.

CONCLUSIONS

These results suggest that peptide leukotrienes may be involved in the pathogenesis of acute pancreatitis in the early stage of the disease and that peptide leukotriene receptor antagonist might be of therapeutic value for treatment of acute pancreatitis.

Gastric subcellular organelle fragility and impaired gastric energy charge levels in rats with caerulein-induced acute pancreatitis: protective effect of anti-ulcer agent, teprenone

When rats were given a supramaximal dose of caerulein (infused intravenously at 5 micrograms/kg.h for 4 h) they developed acute pancreatitis characterized by significantly raised amylase levels in the blood. In this model of acute pancreatitis, reduced gastric adenylate energy charge levels were observed, and the leakage of the lysosomal enzyme, cathepsin B, from gastric lysosomes and of the mitochondrial enzyme, malate dehydrogenase, from gastric mitochondria were both significantly accelerated compared with the control group. The intragastric administration of the anti-ulcer agent, teprenone, at a dose of 5 mg/kg (twice before caerulein infusion) significantly inhibited this gastric damage accompanying acute pancreatitis. These results suggest that gastric subcellular organelle fragility may play an important role in the pathogenesis of impaired gastric energy metabolism accompanying acute pancreatitis, and indicate the possible usefulness of teprenone in preventing this gastric damage.

Anti-ulcer agent, cetraxate hydrochloride (Neuer), prevents subcellular redistribution of lysosomal enzyme in caerulein-induced pancreatitis in the rat

The protective effect of an anti-ulcer agent, cetraxate hydrochloride [4-(2-carboxyethyl)phenyltrans-4-amino- methylcyclohexanecarboxylate hydrochloride], on the exocrine pancreas in caerulein-induced pancreatitis of rats was investigated. Hyperamylasaemia, pancreatic oedema and activation of trypsinogen in the pancreatic tissue, as well as subcellular redistribution of the lysosomal enzyme, cathepsin B, from the lysosomal fraction to the zymogen fraction, were prevented by infusion of 20 mg/kg.h cetraxate for 2 h before caerulein infusion and throughout the 3.5 h of caerulein infusion (5 micrograms/kg.h). The results indicate that cetraxate plays its protective roles against pancreatitis by inhibiting the redistribution of lysosomal enzyme and by activation of trypsinogen; such activities may be clinically useful in preventing pancreatic injuries, particularly in patients with chronic pancreatitis.

A new synthetic protease inhibitor, E-3123, prevents lysosomal and mitochondrial fragility in rat caerulein-induced pancreatitis

The study investigated the protective effect of a new synthetic protease inhibitor, E-3123, a 4-guanidinobenzoate methanesulphonate, on the exocrine pancreas in caerulein-induced pancreatitis of rats both in vivo and in vitro. Hyperamylasaemia, pancreatic oedema and congestion of amylase, as well as cathepsin B leakage from lysosomes and malate dehydrogenase leakage from mitochondria, were prevented by infusion of 5 mg/kg.h E-3123 particularly when infused for 2 h before and during 5 micrograms/kg.h caerulein infusion for 3.5 h. The results indicate that E-3123 plays its protective roles against pancreatitis in the subcellular compartments such as lysosomes and mitochondria, and that such a low molecular weight protease inhibitor as E-3123 may be clinically useful in the treatment of acute pancreatitis.

Protective effect of a microtubule stabilizer taxol on caerulein-induced acute pancreatitis in rat

The effect of taxol, which is a microtubule stabilizer, was examined in a model of acute edematous pancreatitis induced in rat by the administration of caerulein. Prophylactic administration of taxol ameliorated inhibition of pancreatic secretion, increased level of serum amylase, pancreatic edema, and histological alterations in this model. Immunofluorescence studies revealed that taxol stabilized the arrangement of microtubules by the action of promoting tubulin polymerization and prevented inhibition of pancreatic digestive enzyme secretion. In isolated rat pancreatic acini, taxol reversed the inhibition of amylase secretion induced by supramaximal concentrations of cholecystokinin octapeptide and did not affect the binding of cholecystokinin octapeptide to its receptor. The results obtained in this study suggest that microtubule disorganization is the initiating event in caerulein-induced pancreatitis and that the inhibition of pancreatic digestive enzyme secretion by interfering with intracellular vesicular transport due to microtubule disorganization causes caerulein-induced pancreatitis.

Mode of inhibitory action of cholecystokinin in amylase release from isolated rat pancreatic acini--inhibition of secretory process post to protein kinase C-calcium ion systems

The incubation of isolated rat pancreatic acini with low doses (1 x 10(-11)-1 x 10(-10) M) of cholecystokinin-octapeptide (CCK8) induced amylase release. This CCK8-induced amylase release has been shown to be mediated through the protein kinase C activation and the Ca2+ mobilization which are linked to the phospholipase C-mediated hydrolysis of phosphoinositides. However, the incubation of the acini with high doses (1 x 10(-9)-1 x 10(-7) M) of CCK8 reduced amylase release to the level less than that induced by the maximally effective dose (1 x 10(-10) M) of this secretagogue. Under the same conditions, the high doses of this secretagogue did not inhibit the phospholipase C-mediated hydrolysis of phosphoinositides. The stimulatory action of the maximally effective dose of CCK8 in amylase release was mimicked by the simultaneous addition of protein kinase C-activating 12-O-tetradecanoylphorbol-13-acetate (TPA) and Ca2+ ionophore A23187. A high dose (1 x 10(-7) M) of CCK8 reduced the amylase release induced by the combination of TPA and A23187. These results suggest that the high doses of CCK8 inhibit the secretory process post to the protein kinase C-Ca2+ systems and thereby reduce the amylase release induced by the maximally effective dose of CCK8 in rat pancreatic acini.

Enhancement of secretagogue-induced phosphoinositide turnover and amylase secretion by bile acids in isolated rat pancreatic acini

Small amounts (0.1-0.5 mM) of deoxycholate enhanced amylase secretion, which had been induced by submaximal doses of carbachol or cholecystokinin octapeptide, without affecting the maximal levels of these reactions from isolated rat pancreatic acini. Deoxycholate alone did not induce these reactions. The other bile acids such as cholate, chenodeoxycholate, ursodeoxycholate, and taurocholate were also active. Under the similar conditions, deoxycholate enhanced the secretagogue-induced diacylglycerol formation that was derived mainly from the phospholipase C-mediated hydrolysis of phosphatidylinositol and phosphatidylinositol-4-monophosphate. Deoxycholate did not enhance the secretagogue-induced hydrolysis of phosphatidylinositol-4,5-bisphosphate or Ca2+ mobilization. Deoxycholate did not affect amylase secretion, which was induced by the simultaneous addition of protein kinase C-activating 12-O-tetradecanoylphorbol-13-acetate and Ca2+ ionophore ionomycin. Since diacylglycerol and Ca2+ may be responsible for the secretagogue-induced amylase secretion, our results indicate that small amounts of bile acids increase the sensitivity to the secretagogue of diacylglycerol formation and subsequent activation of protein kinase C, and thereby enhance amylase secretion from pancreatic acini.

The effect of protein concentration on the activity of beta-fructosidase from radish seedlings

Radish beta-fructosidase (beta-D-fructofuranoside fructohydrolase, EC 3.2.1.26) is inactived by diluting the enzyme solution and the activity can be restored by addition of bovine serum albumin or other proteins. The use of detergent, high molar salt solutions or silicone-coated tubes showed that decrease of specific activity upon dilution is not linked to adsorption of the enzyme on to glass walls. Albumin neither protects the enzyme from denaturation by heat nor changes its stability during conservation at room temperature. The action of added proteins is not due to removal of an inhibitor from the enzyme solutions. Some polyanions or polycations have the same effect as albumin, but dialysis or chromatography show that they do not act by reassociation of inactive products formed by dilution of the active enzyme. A molecular weight heterogeneity is observed in the enzyme population when chromatography is performed without albumin. This suggests that inactive forms, formed upon dilution, differ slightly in their molecular conformation from the active forms obtained at high protein concentration.

Effects of albumin and other proteins during assay of amylase activity

Addition of albumin, gamma-globulin, alpha-casein or submaxillary mucin to the assay system for chromogenic measurement of human or rat amylase with blue starch increased the amylase activity, albumin having the most effect. These proteins seemed to increase the activity by protecting amylase from inactivation. Amylase activity was higher in urine samples showing proteinuria than in urine samples without detectable protein. It is concluded that amylase assay is more reliable when a final concentration of albumin of 1 mg per ml is added at the dilution step and at the incubation step.