Secretin differentially sensitizes rat pancreatic acini to the effects of supramaximal stimulation with caerulein

Supramaximal stimulation of the rat pancreas with CCK, or its analog caerulein, triggers acute pancreatitis and a number of pancreatitis-associated acinar cell changes including intracellular activation of digestive enzyme zymogens and acinar cell injury. It is generally believed that some of these various acinar cell responses to supramaximal secretagogue stimulation are interrelated and interdependent. In a recent report, Lu et al. showed that secretin, by causing generation of cAMP and activation of PKA, sensitizes acinar cells to secretagogue-induced zymogen activation, and, as a result, submaximally stimulating concentrations of caerulein can, in the presence of secretin, trigger intracellular zymogen activation. We found that secretin also sensitizes acinar cells to secretagogue-induced cell injury and to subapical F-actin redistribution but that it did not alter the caerulein concentration dependence of other pancreatitis-associated changes such as the induction of a peak plateau intracellular [Ca(2+)] rise, inhibition of secretion, activation of ERK1/2, and activation of NF-kappaB. The finding that secretin sensitizes acinar cells to both intracellular zymogen activation and cell injury is consistent with the concept that these two early events in pancreatitis are closely interrelated and, possibly, interdependent. On the other hand, the finding that, in the presence of secretin, caerulein can trigger subapical F-actin redistribution without inhibiting secretion challenges the concept that disruption of the subapical F-actin web is causally related to high-dose secretagogue-induced inhibition of secretion in pancreatic acinar cells.     

Hepatic bile and pancreatic exocrine secretions evoked by gastrointestinal peptides in sheep

The secretory response of hepatic bile and exocrine pancreas to gastrointestinal peptides has been studied in chronically cannulated sheep. Pancreatic juice flow and protein output were evoked dose dependently by intraportal injection of secretin, CCK-8, caerulein, VIP and neurotensin. However, biliary secretion was evoked by only secretin. Biliary and pancreatic exocrine secretions were enhanced by delivered gastric juice into the duodenum as followed by the increased plasma concentration of immunoreactive secretin (IRS). Results suggest that secretin is the major peptide that regulates pancreatic exocrine secretion and hepatic bile production in the sheep.     

The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro.

BACKGROUND: Recent studies clearly demonstrate that Helicobacter pylori (H. pylori) infection of the stomach causes persistent elevation of ammonia (NH3) in gastric juice leading to hypergastrinemia and enhanced pancreatic enzyme secretion. METHODS: The aim of this study is to evaluate the influence of NH4OH on plasma gastrin level and exocrine pancreatic secretion in vivo in conscious dogs equipped with chronic pancreatic fistulas and on secretory activity of in vitro isolated acini obtained from the rat pancreas by collagenase digestion. The effects of NH4OH on amylase release from pancreatic acini were compared with those produced by simple alkalization of these acini with NaOH. RESULTS: NH4OH given intraduodenally (i.d.) in increasing concentrations (0.5, 1.0, 2.0, 4.0, or 8.0 mM/L) resulted in an increase of pancreatic protein output, reaching respectively 9%, 10%, 19%, 16% and 17% of caerulein maximum in these animals and in a marked increase in plasma gastrin level. NH4OH (8 x 0 mM/L, i.d.) given during intravenous (i.v.) infusion of secretin (50 pmol/kg-h) and cholecystokinin (50 pmol/kg-h) reduced the HCO3 and protein outputs by 35% and 37% respectively, as compared to control obtained with infusion of secretin plus cholecystokinin alone. When pancreatic secretion was stimulated by ordinary feeding the same amount of NH4OH administered i.d. decreased the HCO3- and protein responses by 78% and 47% respectively, and had no significant effect on postprandial plasma gastrin. In isolated pancreatic acini, increasing concentrations of NH4OH (10(-7)-10(-4) M) produced a concentration-dependent stimulation of amylase release, reaching about 43% of caerulein-induced maximum. When various concentrations of NH4OH were added to submaximal concentration of caerulein (10(-12) M) or urecholine (10(-5) M), the enzyme secretion was reduced at a dose 10(-5) M of NH4OH by 38% or 40%, respectively. Simple alkalization with NaOH of the incubation medium up to pH 8.5 markedly stimulated basal amylase secretion from isolated pancreatic acini, whereas the secretory response of these acini to pancreatic secretagogues was significantly diminished by about 30%. LDH release into the incubation medium was not significantly changed in all tests indicating that NH4OH did not produce any apparent damage of pancreatic acini and this was confirmed by histological examination of these acini. CONCLUSIONS: 1. NH4OH affects basal and stimulated pancreatic secretion. 2. The excessive release of gastrin may be responsible for the stimulation of basal pancreatic enzyme secretion in conscious animals, and 3. The inhibitory effects of NH4OH on stimulated secretion might be mediated, at least in part, by its direct action on the isolated pancreatic acini possibly due to the alkalization of these acini.     

The interaction of secretin with pancreatic membranes.

1. 125I-labelled secretin bound rapidly and specifically to membranes from cat pancreas. Binding of labelled hormone was competitively inhibited by unlabelled secretin in the same range of concentrations that stimulated pancreatic adenylate cyclase in these membranes. The dissociation constant of the membrane binding sites for unlabelled secretin as evaluated by these displacement experiments was 4.1-10(-9) M and the number of binding sites 1.0 pmol per mg of membrane protein. 2. Studies using different concentrations of [125I]secretin (at a constant ratio of labelled to unlabelled hormone) revealed a similar value of 4-4-10(-9) M for the dissociation constant. 3. Both the association and dissociation rate constants of [125I]secretin binding were temperature sensitive; the dissociation rate constant increased more rapidly with increase in temperature. The ratio k-1/k+1 (at 22 degrees C) gave a dissociation constant of 3.7-10(-9)M which agrees closely with the figure obtained from equilibrium data. These data indicate that 125I-labelled secretin and unlabelled secretin bind to the same binding site on pancreatic membranes, with high affinity. 4. Unlabelled secretin stimulated pancreatic adenylate cyclase with an apparent Km of 8.4-10(-9) M, while [125I]secretin apparently did not stimulate the adenylate cyclase. Together with the binding data this might suggest that different portions of the secretin molecule are responsible for binding and adenylate cyclase activation. 5. Studies on the specificity of [125I]secretin binding carried out with various peptide hormones (glucagon, human gastrin, pancreozymin and caerulein) which are all inefficient in stimulating pancreatic fluid secretin, showed that these hormones have no influence on the binding of [125I]secretin. In contrast, vasoactive intestinal polypeptide, which stimulates pancreatic fluid and bicarbonate secretion, showed a competitive inhibition of secretin binding to the plasma membrane preparation.     

The secretion of adenosin 3',5'-monophosphate after hydrokinetic and ecbolic stimulation in the canine pancreas (author's transl)

The secretion of cAMP is studied in vivo and in the isolated perfused canine pancreas after administration of secretin and CCK or caerulein in comparison with hydrokinetic or ecbolic secretory events as well as with the magnitude and time course of changes in tissue cAMP. 1) The total output of cAMP and pancreatic juice shows a significant and positive correlation after stimulation with secretin. The linear correspondence between cAMP concentration and secretory rates of pancreatic juice beyond 3 ml/5 min and their non-linear, reciprocal correlation at lower rates of fluid secretion point to an active as well as to a passive secretory mechanism for cAMP. 2) CCK and caerulein increase secretion of cAMP too. The output of cAMP however neither corresponds to the time course of protein secretion nor correlates quantitatively with the latter. 3) The behaviour of cAMP secretion and concentration in the pancreatic juice after administration of secretin and CCK or caerulein as well as differs from the changes in tissue cAMP levels. The respective maximum of cAMP output after addition of secretin or ecbolic secretagogues during the greatest decrease in cellular cAMP levels yields on the average about 1% of the estimated reduction in total tissue cAMP content. The results indicate a functional coherence in secretion of pancreatic juice and cAMP but oppose the assumption, that essential amounts of cAMP are released during exocytosis of zymogen granules. The secretion of cAMP may be possibly influenced by cytoplasmatic cAMP levels, but neither reflects the present changes in cellular cAMP nor seems to be of a regulatory importance for the latter.     

In-vivo stimulation of rat pancreatic acinar cells by infusion of secretin

Summary Infusion of synthetic secretin in conscious unrestricted rats for periods up to 24 h was used to study the structural and functional adaptation of pancreatic acinar cells to this secretagogue. Initial dose-response studies established 16 clinical units (CU) per kg and h (corresponding to 4.64 ug x kg^-1 x h^-1) as optimal dose for persistent stimulation of enzyme discharge. Infusion of this dose led to a slow but progressive depletion of enzyme stores with minimal content by 12 h stimulation. As a result of persistent stimulation total protein synthesis in the acinar cells increased after a lag period of 3 h and reached maximal values 90% above controls by 6 and 12 h secretin infusion. No structural equivalent for pronounced fluid and bicarbonate secretion was observed for either acinar or duct cells over the entire dose range (1 to 64 CU x kg^-1 x h^-1) and infusion period (1–24 h), except an increased number of coated vesicles in duct cells.Discharge of enzymes from acinar cells was paralleled by a high frequency of exocytotic images at the luminal plasma membrane and was accompanied by the occurrence of membrane fragments in the luminal space, especially after 3 and 6 h secretin infusion. An increased number of lysosomal bodies at these time points especially in the vicinity of the Golgi complex was interpreted in relation to membrane recycling following massive exocytosis. This pattern of structural and functional adaptation of acinar cells following secretin infusion corresponds to previously described changes following caerulein and carbamylcholine stimulation.Supported by a grant from Deutsche Forschungsgemeinschaft (Ke 113/15-1)     

Nonparallel secretion of enzymes by the rabbit pancreas

Since nonparallel secretion of enzymes by the exocrine pancreas has been demonstrated with several experimental models, we were interested in verifying a recent claim that enzyme secretion remained strictly proportional (parallel) upon stimulation of the in vivo rabbit pancreas. Pancreatic juice was collected by extraduodenal cannulation of the pancreatic duct, in two different protocols. In the first protocol the administration of pentobarbital induces a mild anesthesia. Under this condition, amylase and chymotrypsin secretion remained parallel after cholecystokinin stimulation. In a second protocol, a deeper and constant anesthesia was attained with Fluothane resulting in a lower basal protein output than in the first protocol. Pancreatic secretion was collected under intravenous secretin perfusion (4.5 clinical units X kg-1 X h-1). After stabilization and basal collection periods, pancreatic secretion was stimulated with an i.v. bolus injection of either cholecystokinin (2 Ivy dog units/kg), caerulein (0.1 micrograms/kg), or carbachol (6 micrograms/kg). Upon stimulation of the pancreas, protein output increased an average of 30-fold and there was a concomitant 20-25% decrease in the ratio of the specific activities of amylase to chymotrypsin which resulted from a greater increase in the specific activity of chymotrypsin in pancreatic juice after stimulation of secretion. Thus, under appropriate conditions, nonparallel secretion of enzymes by the exocrine pancreas can be demonstrated in yet another experimental model. Furthermore, the proportion of amylase and chymotrypsin activities in pancreatic juice are once more shown to be dependent, up to a threshold, upon the rate of protein output by this exocrine gland.     

The effect of a synthetic anticholinergic agent, N-methyl hyoscine methyl sulfate, on the exocrine pancreatic secretion of the alert dog]

The inhibitory action of N-methyl hyoscine methyl sulphate (N-methyl scopolamine, an anticholinergic drug) has been studied on the exocrine pancreatic secretion stimulated by secretin + caerulein on the conscious dog provided with Thomas cannulae. The dose-response curve shows an "all or nothing" effect on protein secretion since 0.38 microgram/kg. The inhibition of water and bicarbonate secretion is only observed from 12 micrograms/kg. The inhibitory effect of this drug was much greater than that obtained with similar molar quantities of atropine and no central effect has been observed.     

Comparison of enkephalin and atropine in the inhibition of vagally stimulated gastric and pancreatic secretion and gastrin and pancreatic polypeptide release in dogs

Enkephalins have been detected in vagal nerves and myenteric plexus neurons but no study has been performed to determine their action on vagally stimulated gastric and pancreatic secretion. In this study we infused IV methionine-enkephalin (Met-enk) alone, naloxone (a pure opiate antagonist) alone, or their combination before, during and after vagal stimulation in 4 dogs with esophageal, gastric and pancreatic fistulas. For the comparison, atropine was given before, during and after vagal stimulation in the same animals. Vagal stimulation was obtained by 15 min sham-feeding, which produced an increase in gastric H⁺ output to a peak of about 75% of the maximal response to pentagastrin and pancreatic protein secretion amounting to about 71% of the maximal response to caerulein. It was accompanied by a significant rise in serum gastrin and pancreatic polypeptide (PP) levels. Met-enk inhibited significantly both gastric H⁺ and pancreatic protein secretion and reduced plasma PP but not gastrin levels. Similar effects were obtained after the administration of atropine. The effects of Met-enk were partly reversed by the addition of naloxone. We conclude that (1) enkephalin suppresses vagally stimulated gastric and pancreatic secretion and plasma PP release; (2) these secretory effects of enkephalin seem to be mediated by opiate receptors and could be explained by its inhibitory action on acetylcholine release (“anticholinergic” action) in the stomach and the pancreas.     

Effect of a new CCK-A receptor antagonist,dexloxiglumide, on the exocrine pancreas in the rat

The effect of dexloxiglumide, a new potent cholecystokinin (CCK) antagonist, on pancreatic enzyme secretion and growth was studied in the rat. Pancreatic exocrine secretion was studied both in vitro (isolated and perfused pancreatic segments) and in vivo (anaesthetized animals with cannulation of the common bile duct) whereas the trophic effect was investigated after short-term (7 days) administration of the CCK-agonist, caerulein, or camostate (a potent trypsin inhibitor), with or without dexloxiglumide. CCK-8 stimulated amylase release from in vitro pancreatic segments in a concentration-dependent manner. Dexloxiglumide displaced the concentration response curves to CCK-8 to the right without affecting the maximum response, suggesting a competitive antagonism. The Schild plot analysis of data gave a straight line with a slope (0.90±0.36) not significantly different from unity. The calculated pA₂ for dexloxiglumide was 6.41 ± 0.38. In vivo experiments confirmed results from in vitro studies since intravenous dexloxiglumide reduced pancreatic exocrine secretion induced by submaximal CCK-8 stimulation (0.5 nmol/kg/h) in a dose-dependent manner, the ID₅₀ being 0.64 mg/kg. Both exogenous and endogenous (released by camostate) CCK increased the weight of the pancreas, the total pancreatic protein and DNA, trypsin and amylase content. Dexloxiglumide (25 mg/kg), administered together with caerulein (1 μg/kg), reduced the peptide-induced increase in pancreatic weight, protein and enzyme content. Similarly, when dexloxiglumide was given together with camostate (200 mg/kg), all the observed changes were reduced by concomitant administration of the antagonist. These results demonstrate the ability of dexloxiglumide to antagonize the effects of CCK on pancreatic secretion and growth, suggesting that this compound is a potent and selective antagonist of CCK-A-receptors in the pancreas.     

Glucocorticoids effects on exocrine pancreatic secretion in caerulein-induced acute pancreatitis in the rat.

The present work reports on exocrine pancreatic secretion in control rats, adrenalectomized rats and hydrocortisone-treated (10 mg/Kg/d) rats during 7 days, under normal conditions and after induction of acute pancreatitis with caerulein (20 micrograms/Kg) by 4 subcutaneous injections at hourly intervals. Pancreatic secretion was seen to be affected by the procedure of adrenalectomy, which led to a marked reduction in the secretion of proteins and amylase with respect to control values. This was probably due to the decrease occurring in the zymogen granules in the acinar cells of the exocrine pancreas, a phenomenon which also led to a decrease in pancreatic weight observed in these animals. Treatment with hydrocortisone induced a decrease in the secretion of proteins and amylase, as well as an increase in pancreatic weight. This agrees with the accepted hypothesis that large amounts glucocorticoids stimulate the synthesis and storage of proteins in the exocrine pancreas, reducing the secretory phase. The administration of high doses of caerulein under these conditions led to acute pancreatitis in the three groups of animals. This was paralleled by a dramatic decrease in protein and amylase secretion and by severe interstitial edema of the pancreas and by increases in serum amylase values. In the case of the animals treated previously with hydrocortisone, the latter were tripled with respect to the control animals. The conclusion is offered that since the storage of enzyme proteins is governed by glucocorticoids, which furthermore increase the sensitivity of the acinar cells to stimulation by secretagogues, the administration of these substances during the development of pancreatic lesions such as acute pancreatitis is highly compromising to the organism.     

Different patterns of proteins are secreted by the pig pancreas when stimulated by secretin alone or in combination with caerulein

The protein compositions of pig pancreatic secretions collected under stimulation by secretin alone or in combination with caerulein were compared by SDS polyacrylamide gel electrophoresis. Different sets of proteins were observed in these two different conditions. One of the major proteins secreted under secretin alone was immunologically similar to the 92 kDa glycoprotein characteristic of the pig zymogen granule membrane. Since its proportion in the two secretions was drastically different and since this protein is exclusively found in the acinar cell, these observations support the view that the proteins released by the pig pancreas under secretin stimulation alone, and under the combination of secretin + caerulein do not originate from the same intracellular pool of the acinar cell and that the secretin-induced secretion does not derive from zymogen granules.     

THE EFFECTS OF SECRETAGOGUES ON THE INCORPORATION OF [2-3H]MYOINOSITOL INTO LIPID IN CYTOLOGICAL FRACTIONS IN THE PANCREAS OF THE GUINEA PIG IN VIVO

Stimulation of enzyme secretion in the pancreas on injection of a single dose of the cholinergic drug, pilocarpine, was associated with an increased incorporation of [2-³H]myoinositol into a lipid, which was previously characterized as phosphatidylinositol. Stimulation of enzyme secretion by hourly injection of the pancreozymin congener, caerulein, led to more increased phosphatidylinositol synthesis than with a single injection of pilocarpine. The amylase level of the pancreas remained at a low level as long as caerulein was injected, indicating continued stimulation of enzyme secretion even though increased phosphatidylinositol synthesis ceased after 6 h. Feeding gave the same stimulation of phosphatidylinositol synthesis as caerulein. The major synthesis of phosphatidylinositol in controls and the stimulation of phosphatidylinositol synthesis by pilocarpine was entirely confined to the microsome fraction throughout the experiments (up to 18 h). This shows that there is no flow of microsomal membrane (smooth- or rough-surfaced endoplasmic reticulum) to other membranous structures throughout the secretory cycle and beyond. It is concluded that the stimulation of phosphatidylinositol synthesis by pancreatic secretagogues is confined to microsomal elements and does not play any role in membrane flow.     

In vitro stimulation of prostaglandin synthesis in the rat pancreas by carbamylcholine, caerulein and secretin

Rat pancreas pieces spontaneously released PGE₂ (2.3 ng/100 mg × 45 min) and PGF_2α (7.6 ng/100 mg × 45 min). This release corresponds probably to a neo-synthesis since it was abolished by indomethacin. Carbamylcholine (≥ 10 μM), caerulein (≥ 10 nM) and secretin (≥ 10 nM) stimulated the release of PGE₂ and PGF_2α : the concentrations of stimulators required to increase PGs release were thus much higher than those which trigger enzyme secretion. Atropine specifically inhibited the cholinergic stimulation, whereas indomethacin blocked the stimulatory effects of all secretagogues. Stimulation of PGE₂ and PGF_2α release was reduced in a Ca⁺⁺-free medium, abolished by EGTA and mimicked by the ionophore A23187, underscoring the crucial role of Ca⁺⁺ in the regulation of PGs synthesis by the pancreas. Neither PGE₂ nor PGF_2α stimulated enzyme secretion in this system and indomethacin did not inhibit the secretory effect of carbamylcholine. Increased synthesis of prostaglandins in response to pancreatic secretagogues does not appear to be involved in the process of enzyme secretion.     

Effects of some gastrointestinal peptides on pancreatic growth in rats (preliminary results)

The purpose of this study was to estimate the effects of cholecystokinin (CCK), somatostatin (SS) pancreatic polypeptide (PP) and their interaction with each other, given them in single doses, on pancreatic secretion and pancreatic growth after long-term treatment in rats. The acute secretory effects of the above mentioned peptides were studied on conscious rats supplied with pancreatic, gastric and jugular vein cannulae. The pancreatic growth was characterized by measurements of pancreatic weight, desoxyribonucleic acid (DNA), protein, trypsin and amylase content after 5 days treatment. Amylase output was increased by caerulein alone, and given it in combination with somatostatin (SS), while its value decreased by SS alone. After 5 days treatment, the pancreatic weight, trypsin and amylase activity (hypertrophy) was increased by caerulein, and these values were not altered by S alone. In combinative administration of caerulein with somatostatin, the stimulatory effect by caerulein was decreased. PP given alone or in combination with caerulein decreased both the basal and stimulated amylase output. PP given for 5 days decreased pancreatic trypsin and amylase contents and counteracted the stimulatory effect by caerulein to these enzymes' contents. It has been concluded that: 1. caerulein stimulates both pancreatic enzyme secretion and pancreatic growth; 2. somatostatin inhibits the pancreatic secretion and caerulein induced pancreatic growth, but it does not affect the spontaneous growth of pancreas; 3. pancreatic polypeptide inhibits the pancreatic secretion and decreases pancreatic trypsin and amylase contents.     

Electrophoretic and cytological evidence for heterogeneity of pancreatic acinar cell responsiveness to carbachol,caerulein and secretin

Summary Incubation of rat pancreatic lobules for 90 min with optimal concentrations of caerulein, carbachol or secretin caused the release of about 30% of the amylase content. Combination of secretin with carbachol or caerulein increased the amylase output to about 40%. With secretin, as with carbachol or caerulein, heterogeneity of cellular responsiveness was observed, some acini being partially or completely depleted of their zymogen granules, whereas others appeared to be resting. When secretin was combined with carbachol or caerulein, granule depletion, originally confined to small groups of neighbouring acini, spread to form large areas of degranulated cells, sometimes comprising a whole section of a lobule.In dispersed acini, under the same conditions, carbachol caused the release of about 60% of the amylase content, and secretin 40%. When both secretagogues were combined, a significant increase to 78% was observed. Under these conditions, there was some important cellular damage, as indicated by the release of 20% of the amylase content and between 6 and 12% of lactate dehydrogenase into the media, in the absence of stimulus. These results were corroborated by cytological observations. On the basis of their secretory response two groups of acini can be distinguished, those that respond to carbachol, caerulein or secretin and those that respond to the combination of secretin with carbachol or caerulein. Electrophoretic patterns of secretory proteins released by lobules stimulated by these different types of secretagogues were essentially similar. The pattern was quite different, however, in the absence of a stimulus. The most striking feature was the presence of a band at 63 Kd whereas a 73.5 Kd band was found only under conditions of stimulation. The latter results support the view that under resting and stimulated conditions secretory proteins are released from distinct compartments in the acinar cell.Abbreviations used PMSF phenylmethylsulfonyl fluoride - Carbachol carbamylcholine chloride - SBTI soybean trypsin inhibitor     

Isoelectric focusing studies of human pancreatic secretion

Pure bile, pancreatic and duodenal human juices have been analyzed by isoelectric focusing, either at rest or upon stimulation with caerulein. In rats, stimulation has also been performed with secretin. Twenty bands have been resolved and quantified in the pancreatic secretion. By developing zymograms, a number of isozymes have been identified: 6 isoamylases [pI's 7.2, 7.1 and 6.6 (major) and pI's 7.4, 6.7 and 5.8 (minor)], 3 lipases [pI's 7.0 and 6.8 (major) and 6.4 (minor)], two major alkaline proteases (pI's 9.8 and 8.4) and one major acidic protease (pI 4.3) and one band of RNAase activity (pI 8.6). The stimulation kinetics follow a mechanism according to Palade, indicating uniform response to secretogogues, parallel intracellular transport and parallel discharge of pancreatic exocrine proteins.     

Neurotensin interacts with carbachol, secretin, and caerulein in the stimulation of the exocrine pancreas of the rat in vitro

In the present investigation the effect of neurotensin on pancreatic secretion of isolated pancreatic lobules from the rat was examined. We found a dose- and time-dependent stimulation of amylase release beginning with a concentration of 10(-9) M neurotensin. This response was potentiated by the cholinergic agonist carbachol, the gastrointestinal peptide secretin, and the CCK analogue caerulein. As we found neurotensin-immunoreactive nerves within the pancreas and as neurotensin-like immunoreactivity is present in the circulation (found previously), neurotensin may well be a further peptide taking part in the regulation of exocrine pancreatic secretion either as a hormone or a neurotransmitter. Neurotensin would then cooperate with cholinergic mechanisms, secretin, and CCK.     

A new, rapid, method for preparation of dispersed pancreatic acini.

A new method for the preparation of pancreatic acini is described. The method is simple and much more rapid than previously described techniques, the time required for preparation of pancreatic acini being 20 min from removal of the pancreas. Acini prepared with this method perform in a superior manner when stimulated by either caerulein or secretin. Thus this new technique would be ideal for use in binding and secretion studies.