Pancreatic secretion in the rat influenced by the low molecular weight serine proteinase inhibitor Gabexate mesilate

Effects of gabexate mesilate (FOY) on amylase and phospholipase A2 in human serum and pancreatic juice

The precise inhibitory action of gabexate mesilate (GM) on the various pancreatic enzymes remains unclear. We designed this study to investigate the enzyme inhibitory action of GM in the serum and directly in the pancreatic juice. We observed 16 cases with postoperative pancreatic drainage. Patients were randomly assigned to one of two groups, to receive GM at a dose of 600 mg/24 hr (treated group: 8 patients) or a physiological solution (control group: 8 patients) by continuous intravenous infusion. In both groups pancreatic juice and serum were sampled three times: before infusion began (T0) and at 12 hr (T1) and 24 hr after infusion ended (T2). At the end of the study, seven patients received octreotide and the volume of pancreatic secretion was determined. No statistical difference was observed in serum amylase and phospholipase A2 activity in the treated and control groups. On the contrary, amylase and phospholipase A2 activity in the pancreatic juice diminished significantly only in the treated group, and in these patients a GM metabolite was also detectable in the pancreatic secretion. The volume of pancreatic secretion decreased only after infusion of octreotide. The enzyme inhibition in the pancreatic gland itself and the central role of inhibition of phospholipase A2 in the enzyme cascade responsible for activating other proteases, confirm the therapeutic use of GM in acute pancreatitis. An association of GM and octreotide during acute pancreatitis should be useful because of their different mechanisms.

Gabexate mesilate (FOY) inhibition of amylase and phospholipase A(2) activity in sow pancreatic juice

We designed this study in sows to investigate the enzyme inhibitory action of gabexate mesylate (GM) directly in the pancreatic juice. We studied 16 sows, each weighing about 130 kg. The pancreatic duct was identified and cannulated to collect the pancreatic juice. Sows in the treated group received intravenous GM infusion at a dose of 1000 mg over 24 h. Control sows underwent the same sampling schedule while receiving physiological solution. GM inhibited the two pancreatic enzymes amylase and phospholipase A(2) (PA(2)) in pancreatic juice. Thus, the enzyme inhibition in the pancreatic gland itself and the central role of (PA(2)) inhibition in enzyme cascade responsible for activating other proteases confirm the therapeutic use of GM in acute pancreatitis.

Chronic oral administration of synthetic trypsin inhibitor camostate reduces amylase release from isolated rat pancreatic acini

In the present study, we examined stimulus-secretion coupling in pancreatic acini prepared from rats given synthetic protease inhibitor camostate at a dose of 200 mg/kg body wt by an orogastric tube once a day for 10 d. Camostate treatment significantly increased pancreatic weight, protein, DNA, and enzyme contents. In acini prepared from the camostate-treated rats, responsiveness to both CCK-8 and carbamylcholine was greatly decreased with no shift in the dose-response curves compared to control acini prepared from saline-treated rats. There were no major changes in the affinity for both high- and low-affinity sites of CCK receptors, but there was a significant reduction in the capacity of low-affinity site based on acinar protein. Responsiveness to secretin in the camostate-treated rat acini was also significantly reduced compared with that in the controls. However, amylase release from the camostate-treated rat acini in response to an increase in intracellular calcium levels induced by the calcium ionophores A23187 or to an increase in intracellular cyclic 3',5'-monophosphate (cyclic AMP) levels caused by 8 bromo cyclic AMP was not significantly different from the control rat acini, suggesting that both Ca(2+)-dependent tyrosine kinase and nucleotide-activated kinases are not impaired. On the other hand, the responsiveness to phorbol ester TPA, which stimulates amylase secretion via a calcium-independent cascade by activating protein kinase C directly, was reduced in the camostate-treated rat acini compared with the controls. These results suggest the possibilities that the reduced amylase secretion in the camostate-treated rats is owing to alterations in both the transmembrane signal transduction and the phosphorylation of regulatory proteins by the Ca(2+)-independent, protein kinase C-dependent mechanisms.

Endocrine and exocrine pancreatic function after camostate-induced growth of the organ

It is well known that oral administration of camostate induces hyperplasia and hypertrophy of the rat pancreas. It is not clear, however, whether pancreatic hormone and enzyme secretion are affected by camostate treatment. In rats, daily administration of 200 mg camostate/kg b. wt for 14 days significantly increased pancreatic weight and pancreatic content of DNA, protein, amylase, lipase, trypsin and chymotrypsin, as well as the amount of insulin, glucagon and somatostatin. In the intact animal, blood glucose levels and serum concentrations of insulin and glucagon in response to an oral glucose load were not impaired after camostate treatment. In the isolated perfused pancreas, however, insulin and glucagon secretions were reduced, whereas somatostatin release was not affected. The volume of pancreatic juice produced by the unstimulated isolated perfused organ, as well as protein and enzyme secretion, were increased after camostate treatment. Likewise, the isolated perfused pancreas from camostate-treated rats secreted a larger volume of pancreatic juice and more protein in response to cholecystokinin (CCK), while enzyme secretion was affected in a non-parallel manner: amylase release was markedly reduced, lipase release was unchanged, and release of trypsin and chymotrypsin was increased.

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.

Hepatic and pancreatic metabolism and biliary excretion of the protease inhibitor camostat mesilate

The hepatic metabolism and biliary and pancreatic excretion of the serine protease inhibitor camostat mesilate and its metabolites FOY-251 and GBA were studied in rats in vivo and in in sutu liver-perfusion experiments. After oral feeding (100 mg/kg) and iv infusion (5 mg/kg.h) of camostat mesilate, the original compound and both metabolites appeared in bile, but could not be detected in pancreatic juice. In plasma, only FOY-251 and GBA were detected. In the perfused rat liver, camostat mesilate (10 microM) was eliminated by 33.8% and its molar rate of degradation to FOY-251 was 25.1%. During the study period about 0.1% of camostat mesilate and FOY-251 appeared in bile. The liver perfusion of FOY-251 or GBA revealed very low hepatic extraction rates of 10.3 and 2.4%, respectively. In conclusion, the low hepatic extraction rate of camostat mesilate and its metabolites leads to high concentrations of the active metabolite FOY-251 in plasma. Camostat mesilate and its metabolites are effectively excreted into bile, but not in rat pancreatic juice.

Pancreatic response in rats and mice to trypsin inhibitors from soy and potato after short- and long-term dietary exposure

The effects on the pancreas of chronic (95 wk) dietary exposure to protease inhibitors from soy and potato were compared in rats and mice. Soy and potato trypsin inhibitor (TI) concentrates were prepared from defatted raw soy flour and potato juice, respectively, by selective precipitation and ultrafiltration. Animals were fed a diet in which casein supplied approximately 20% protein. Each concentrate (less than 1% of the diet) was added to provide 100 and 200 mg of trypsin inhibitor activity per 100 g of diet. In short-term (28 d) experiments in rats, both sources of TI decreased the apparent nutritional quality of casein and produced pancreatic hypertrophy consistent with a hormonally mediated feedback mechanism for pancreatic adaptation to diet that is interactive with the nutritional status of the animal. After long-term feeding (95 wk), soy and potato TI produced dose-related pancreatic pathology in rats consisting of nodular hyperplasia and acinar adenoma, which was typical of that associated with raw soy flour. Although mice responded similarly to rats to soy TI in short-term (28-d) feeding experiments, they were resistant to the formation of these lesions following long-term feeding. This considerable species variation in propensity to develop preneoplastic and neoplastic lesions of the pancreas is not predicted by the short-term hypertrophic and hyperplastic response of the pancreas to TI.

Effect of a low-molecular weight serine proteinase inhibitor (camostate) on amylase release from isolated pancreatic acini

Oral administration of the proteinase inhibitor camostate to rats results in a characteristic regulation of pancreatic enzyme synthesis and release. These effects are thought to be mediated by an endogenous cholecystokinin release in answer to camostate feeding. An additional direct effect of the compound could be exerted directly on the acinar cell. We evaluated in the present study whether the acute or chronic influence of camostate alters the basal or cerulein-stimulated enzyme release from isolated rat acini. Neither basal nor cerulein-induced (10(-12) to 10(-8) M) amylase release from acini of non-pretreated donor rats were influenced in the presence of 5, 50, or 500 microM camostate. After oral feeding of camostate (200 mg/kg b.wt. daily) over 5 days pancreatic growth occurred. In experiments with acini obtained from the camostate-pretreated rats highly significant reductions of the cerulein-induced amylase release were found as compared to controls. Our findings exclude a direct effect of camostate on the secretory process of pancreatic acinar cells. However, after repeated oral pretreatment of donor rats a "desensitization" of acini against cerulein stimulation occurs. This latter effect is ascribed to elevated endogenous cholecystokinin which was released in response to camostate feeding.

Influence of a small molecular weight proteinase inhibitor, gabexate mesilate (FOY), on insulin receptor function in vitro

The effects of the low molecular weight serine proteinase inhibitor FOY (gabexate mesilate) upon insulin action was studied in three different experimental systems. Placenta membranes containing insulin receptors preincubated with FOY (10 microM) showed a reduction of insulin-stimulated tyrosine kinase activity (p less than 0.01). However, FOY (0.1-100 microM) did not affect the insulin-stimulated tyrosine kinase activity in a preparation of solubilized and partially purified insulin receptors from placental membranes. Isolated adipocytes were used to study the effect of FOY on intact cells. FOY neither altered the insulin induced inhibition of the catecholamine-stimulated lipolysis nor (at the low concentration of 0.1 mM) the stimulation of glucose transport by the hormone. High concentrations (0.5 mM) of FOY decreased the effect of insulin on the hexose transport.