[The effect of distal transposition of the pancreatic duct on gastric motility]

The stomach motor activity activated by mashed meat and bread prior to and within 3 months after transposition of main pancreatic duct into the proximal portion of the jejunum, was studied in dogs with fistulae. The distal transposition of the pancreatic duct was found to reduce significantly the rate of the stomach contractions, to increase its tonus in later period and to be able to reduce the strength of the stomach contractions in delayed hours after feeding. The duodenal mechanisms of the regulation of the stomach motility were transformed in conditions of a distal shift of the pancreatic secret inflow into the intestine.

Anion selectivity and block of the small-conductance chloride channel on pancreatic duct cells

Rat and human pancreatic duct cells have small-conductance Cl- channels in their apical plasma membranes. These channels are regulated by secretin and adenosine 3',5'-cyclic monophosphate and may function in parallel with Cl(-)-HCO3- exchangers to allow HCO3- secretion from the duct cell. Using the patch-clamp technique, we have now determined the anion permeability sequence of the channel as NO3- greater than Br- approximately I- approximately Cl- much greater than HCO3- much greater than gluconate. From this we conclude 1) that anion permeation involves a weak interaction with charged sites inside the channel pore, 2) that because of the low HCO3-/Cl- permeability ratio it is unlikely that significant amounts of HCO3- could be secreted directly via the channel, and 3) that channel permeability may determine the anion selectivity of secretion. We also show that 5-nitro-2-(3-phenylpropylamino)benzoic acid blocks the small-conductance Cl- channel, whereas 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid has no effect.

Functional and morphological relationships between the feline main pancreatic and bile duct sphincters

To analyze the relationships between the bile duct and main pancreatic duct sphincters, the resistance to flow through these sphincters was studied simultaneously with perfusion techniques in anesthetized cats. Basal flow resistance was higher in the pancreatic sphincter than in the bile duct sphincter. The pressure in one duct system was not affected by the flow in the other. The muscular activities in the sphincters were usually well coordinated. Distention of the upper biliary tract or the pancreatic duct system reduced the flow resistance in both sphincters. Cholecystokinin-8 (0.01 micrograms), duodenal distention, and sublingual glyceryl trinitrate (0.4 mg) also relaxed both sphincters, whereas secretin in a dose that induced pancreatic secretion had no consistent effect. Morphine increased flow resistance in both systems. These functional studies indicate that the 2 sphincters share smooth muscle fibers at the level where the flow resistances arise, and there are thus no grounds for separate control of the sphincters. There was no evidence of a functionally common sphincter ampulla. The conclusions drawn from the manometric results were supported by morphological findings in this study.

An in vitro method for studying endocrine and exocrine secretion in the perfused isolated rabbit pancreas

This work describes a perfusion technique adapted to the isolated rabbit pancreas allowing investigation of both the endocrine and exocrine function. The pancreas-duodenum-stomach-spleen complex is removed and perfused with a modified Krebs Ringer Bicarbonate medium. The surgical steps leading to the removal of the complex are described. The endocrine response is studied by measuring insulin release when the pancreas is submitted to successive glucose stimulations and the exocrine function is evaluated by the alpha-chymotrypsin activity of the pancreatic juice harvested during the perfusion.

Cell features in pancreas of prediabetic and diabetic rabbits after Wirsung duct ligation. Histochemical and histoenzymatic studies

Kinetic studies of the histochemical and histoenzymatic behavior of rabbit pancreatic parenchymas were performed 5, 30 and 90 days after Wirsung duct ligation. In control pancreas, some enzyme activities (EA) were more prominent in Langerhans islets [glucose-6-phosphatase, glucose-6-phosphate dehydrogenase (DH), isocitrate DH, glycerol-3-phosphate DH, NADPH DH], others were strongly marked in acini and ducts (alkaline phosphatase, beta-glucuronidase, acid esterase aryl-sulfatase). Histochemical and enzyme abnormalities observed in experimental rabbits reflect the post-ligation degenerative and reactive processes in both exocrine and endocrine pancreas: (1) the decrease in Krebs cycle and pentose pathway linked EA and the increased lysosomal and acid phosphatase EA reflect early (day 5) degeneration and necrosis of islets and acini (day 30); (2) proliferative processes in developed ductal epithelia are shown by an increase in both glycolytic and lysosomal EA (days 30 and 90); (3) connective tissue neogenesis and interstitial fibrosis occurred as shown by activated beta-glucuronidase, aryl-sulfatase, alkaline phosphatase and increased ribonucleoproteins and glycoaminoglycans contents (day 30); (4) on day 90, the neoformed cell clusters presenting glucose-6-phosphatase positivity (B-cell marker) are seen in the pancreas remnant. At the same time, blood insulin level increases correlated with a decrease of hyperglycemia.

Pancreatic and biliary pressure changes during ERCP

Injection of contrast is a prerequisite for endoscopic retrograde cholangiopancreatography. Such injection into the biliary and pancreatic duct systems may require considerable force. This paper reports the changes in pressure that result within the duct systems and highlights the significant pressure rise that occurs within the pancreatic duct.

Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis

Absorbed and processed mucosal neutral lipid has been shown to be composed of at least two pools of triacylglycerol. One is likely to subserve chylomicron formation, and the other appears to be transported from the intestine via a nonlymphatic route. In the present study, 50 +/- 5% of the mucosal lipid pellets was centrifuged at 75,000 g.min [low-speed pellet (LSP)]. Discontinuous sucrose density gradient centrifugation of LSP showed that 61 +/- 7% of the lipid banded at the 0.25-0.86 M sucrose interface. Neutral lipid analysis showed that this subfraction was only 58% triacylglycerol, suggesting it was undergoing hydrolysis. Active lipolytic activity in vitro was found on incubation. The lipase had an alkaline pH optimum (pH 8.5) and persisted despite pancreatic ductular diversion. Lipolysis in vivo in a LSP fraction was shown by infusing [14C]glyceryltrioleate for 3.5 h followed by [3H]glyceryltrioleate for 30 min. Discontinuous sucrose density centrifugation of the LSP followed by an analysis of the lipids at the 0.25-0.86 M sucrose interface showed that 14C-neutral lipids were only 70 +/- 6% triacylglycerol, whereas 3H-neutral lipids were 88 +/- 2% triacylglycerol. 3H entered LSP slowly compared with the floating lipid in the same centrifuge tube. These studies suggest both in vivo and in vitro mucosal lipolysis by a specific, alkaline-active lipase. The turnover rate of LSP is likely to be slow by comparison with neutral lipid floating to the top of the centrifuge tube.

Experimental chronic pancreatitis in the pig

Chronic pancreatitis was induced in 22 piglets by dividing all pancreatic attachments to the duodenum; five sham-operated piglets served as controls. Two piglets died of postoperative complications. The animals were autopsied 2, 4, or 6 weeks postoperatively. All operated animals developed chronic pancreatitis. Concomitant with the development of interstitial fibrosis, an increasing progressive atrophy of the exocrine parenchyma occurred, with preservation of the islets of Langerhans. This atrophy and fibrosis were considerable already after 2 weeks. In one piglet only there was some acute inflammation and fat necrosis, whereas all showed at least moderate chronic inflammation, which did not change with time. The growth of the piglets stopped, and all had diarrhoea, which was thought to reflect exocrine insufficiency. Two animals (9%) developed a large pancreatic pseudocyst, and all animals had wide pancreatic ducts. The endocrine function was undisturbed. Intravenous glucose tolerance tests showed that the animals did not become diabetic. This model is appropriate for the study of experimental pancreatitis.

Two types of chloride channel on duct cells cultured from human fetal pancreas

Using the patch-clamp technique, we have identified two types of chloride channel on duct cells cultured from human fetal pancreas. The channel we observed most frequently exhibited slight outward rectification, had a conductance of 4-7 pS in cell-attached patches, and was present on the apical plasma membrane where it usually occurred in clusters. Its open-state probability was not markedly voltage dependent but was increased up to threefold by exposing duct cells to secretin (10 nM), dibutyryl cyclic AMP (1 mM), or forskolin (1 microM). The other type of chloride channel was only rarely observed. Its current-voltage relationship exhibited marked outward rectification, giving chord conductances of 19 pS for inward currents and 53 pS for outward currents. Although this channel could be activated by sustained depolarization of excised patches, once activated the open state probability was not voltage dependent. While the physiological role of these channels is not firmly established, the small-conductance channel might function in parallel with a Cl- -HCO-3 exchanger to provide a mechanism for electrogenic bicarbonate secretion from the duct cell.

Effect of pancreatic juice diversion on secretin release in rats

We investigated a possible role of secretin in the mechanism of exocrine pancreatic secretion after exclusion of pancreatic juice from the intestine in anesthetized rats. Diversion of pancreatic juice from the duodenum resulted in a significant increase in plasma secretin concentration from 0.76 +/- 0.39 pM at 0 time to 3.09 +/- 0.30 pM at 4 h after diversion. This increase in secretin coincided with a steady but significant increase in pancreatic secretion of volume and bicarbonate. Intraduodenal administration of fresh pancreatic juice completely reversed the diversion-induced increases in both plasma secretin and pancreatic secretion. Intravenous injection of a rabbit-antisecretin serum blocked the increase of pancreatic secretion during diversion of pancreatic juice from the duodenum. Thus, we conclude that endogenous secretin is involved in a hormonal mechanism regulating increased pancreatic exocrine secretion in pancreatic juice-diverted rats.

[Evacuatory activity and motor periodicity of the stomach after transposition of the pancreatic duct into the jejunum]

The transposition of the pancreatic duct into the jejunum accelerated the evacuation of acid solution from the stomach while decelerating that of bicarbonate solution. The motor periodicity of the stomach obviously changed, at that: the duration of working and resting phases, the rate and the strength of the stomach contractions. The data obtained suggest regulatory effects of the pancreatic juice from the duodenum upon the stomach motor-evacuatory activity.

Long-term canine duct-occluded segmental pancreatic autografts: endocrine function

This study examines the endocrine function of duct-obliterated canine segmental autografts for periods up to 5 years posttransplant. Overall the response profile of autografted animals was subnormal. After intravenous glucose tolerance tests K-values in transplanted animals (2.8 +/- 0.9%/min) were significantly lower than normal (4.6 +/- 1.2% min, p less than 0.001). After oral glucose stimulation, blood glucose in the autografted dogs reached a mean peak of 10.6 +/- 2.8 mmol/L whereas in normal dogs the peak value was 6.0 +/- 1.0 mmol/L (p less than 0.002). The mean insulin response in autografted dogs showed lower insulin concentrations in the early stages of the test, whereas insulin secretion after glucagon stimulation was significantly reduced in autografted dogs. Intravenous glucose tolerance tests were analyzed by calculating K value or measuring a single blood glucose concentration 40 min after glucose injection. This value had a high correlation with the K value (r = 0.967). No progressive deterioration of graft function up to 5 years was found. Glycosylated hemoglobin levels were measured in autografted (646 +/- 59 pmol/mg) and normal dogs (620 +/- 85 pmol/mg) and no significant difference was found. In conclusion, duct-occluded segmental pancreatic autografts were shown to have a reduced functional capacity but there was no deterioration of function up to 5 years after duct-occlusion and grafting. The degree of metabolic control may be sufficient to prevent diabetic complications.

Quantitative assessment of long-term changes in insulin secretion after canine duct-obliterated pancreas transplantation

In this study, we have quantitatively assessed the changes in insulin-secreting capacity after duct-obliterated segmental pancreatic autotransplantation in dogs. To this end, we have used a technique for the sampling of the complete and undiluted pancreatic venous blood with simultaneous flow measurement, by which means the actual insulin-secreting capacity was determined in a direct fashion. Histologic changes were analyzed in addition in order to address the underlying mechanisms of the changes in insulin-secreting capacity. Intraoperative glucose-stimulated insulin secretion of the left pancreatic lobe was measured before (group I, n = 8), at 6 weeks (group II, n = 5), and at 18-24 months (group III, n = 7) after duct-obliterated segmental pancreatic autotransplantation. At all 3 intervals, histologic analysis was performed. Since the experiments in groups I-III were performed under general anesthesia, a 4th group of dogs (group IV, n = 6) was studied in addition in order to determine the effect of general anesthesia on glucose metabolism. K-values appeared to be reduced to 1/5 and peripheral insulin response (AUC) to about 1/3 of the values obtained from fasting conscious dogs. Although all animals in groups I-III had normal fasting glucose levels and normal K-values at each test interval, a 75% reduction of insulin secretion after duct-obliterated transplantation was observed. Insulin secretion not only showed marked quantitative changes but significant qualitative alterations in glucose-stimulated insulin response were found. Disturbance of functional islet architecture appears to be the main causative factor in the decrease in insulin secretion. If applicable to man, our results indicate that especially the duct-obliterated graft, with its borderline endocrine capacity, is prone to loss of sufficient graft function by the damage induced by eventual rejection crises.

Morphologic evidence of interactions between adult ductal epithelium of pancreas and fetal foregut mesenchyme

First, tissue recombinants were used to determine the residual capability of adult endodermal pancreatic ductal epithelium to form islets. Second, adult epithelium was challenged by placing it between adult stroma and fetal mesenchyme to investigate the epithelial response (subsequently called challenge grafts). Trypsin was used to isolate adult mouse (heteroplastic) or rat (homoplastic) pancreatic ductal epithelium and fetal rat mesenchyme. All the adult epithelium was maximally stressed with alloxan to control for beta-cell contamination. Fetal mesenchyme was layered with epithelium in vitro for at least 48 h. Subsequently, the recombinants were grafted into nude mice and allowed to develop for 4-6 wk. To assess development, grafts were removed and fixed for both light and electron microscopy. In general, the grafts became organized into vesicles, tubules, and buds, many of which were in the form of vascularized isletlike structures. Epithelium responded with mitosis and intercellular adhesion. the range of cytodifferentiation varied. Culture time, age, and adhesiveness of the fetal mesenchyme and the amount of adult epithelium used in making the recombinants influenced the degree of differentiation. Analysis of fine structure of isletlike structures revealed cells with small electron-dense granules. These observations provide evidence for activation of endodermal epithelium taken from an adult mammal.

The pancreatic duct cell: proliferative capabilities, specific characteristics, metaplasia, isolation, and culture

The pancreatic duct cell, although a minor cell type of the pancreas, plays an important role in fluid/electrolyte and mucin secretion, and has been implicated in the development of pancreatic cancer, alcoholic pancreatitis, and cystic fibrosis. In the normal pancreas, the duct cell has the same low proliferative rate as acinar and endocrine cells. Under certain pathological circumstances, duct cells, as well as acinar and islet cells, may be stimulated to proliferate more rapidly. Pancreatic duct cells exhibit certain features not shared by acinar and/or endocrine cells, including a variety of antigens, mucins, enzymes, and morphological features. Adult duct cells resemble fetal pancreatic duct-like cells morphologically, but they have differentiated to at least a limited extent from their precursor cell type. Although there is no evidence that duct cells differentiate into acinar cells after pancreatic morphogenesis is complete, some islet cells develop from duct epithelium in the early postnatal period. Some pathological conditions may lead to the postnatal formation of islet cells from duct cells and may cause acinar cells to become duct-like in morphology or to die and be replaced by duct cells. A better understanding of duct cells is now possible because of the development of techniques for their isolation and culture free from other cell types. Several such techniques are reviewed.

Properties of the luminal membrane of isolated perfused rat pancreatic ducts. Effect of cyclic AMP and blockers of chloride transport

The aim of the present study was to investigate by what transport mechanism does HCO-3 cross the luminal membrane of pancreatic duct cells, and how do the cells respond to stimulation with dibutyryl cyclic AMP (db-cAMP). For this purpose a newly developed preparation of isolated and perfused intra- and interlobular ducts of rat pancreas was used. Responses of the epithelium to inhibitors and agonists were monitored by electrophysiological techniques. Addition of HCO-3/CO2 to the bath side of nonstimulated ducts depolarized the PD across the basolateral membrane (PDbl) by about 9 mV, as also observed in a previous study [21]. This HCO-3 effect was abolished by Cl- channel blockers or SITS infused into the lumen of the duct: i.e. 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB, 10(-5) M) hyperpolarized PDbl by 8.2 +/- 1.6 mV (n = 13); 3',5-dichlorodiphenylamine-2-carboxylic acid (DCl-DPC, 10(-5) M) hyperpolarized PDbl by 10.3 +/- 1.7 mV (n = 10); and SITS hyperpolarized PDbl by 7.8 +/- 0.9 mV (n = 4). Stimulation of the ducts with db-cAMP in the presence of bath HCO-3/CO2 resulted in depolarization of PDbl, the ductal lumen became more negative and the fractional resistance of the luminal membrane decreased. Together with forskolin (10(-6) M), db-cAMP (10(-4) M) caused a fast depolarization of PDbl by 33.8 +/- 2.5 mV (n = 6). When db-cAMP (5 x 10(-4) M) was given alone in the presence of bath HCO-3/CO2, PDbl depolarized by 25.3 +/- 4.2 mV (n = 10).(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in carbohydrate metabolism after major resection of the pancreas, with special reference to the fibrotic pancreas caused by ligation of the pancreatic duct]

Fibrotic pancreas was caused by ligation of the pancreatic ducts in mongrel dogs. Four weeks later, reconstruction of the pancreatic duct and major pancreatic resection were performed. Changes of carbohydrate metabolism and functional and morphological changes of islet cells in the remnant pancreas were investigated. 1) Immediately after resection of more than 84% of the fibrotic pancreas, diabetes developed, and insulin and glucagon secretion decreased, accompanied with marked degeneration of B, A and D cells in the islets. 2) During the early periods after 63 to 84% pancreatectomy, secretion of both insulin and glucagon decreased, and then showed a tendency to recover, but later the secretion gradually decreased again and so-called Sandmeyer's diabetes developed. The size of the islets and the number of B cells decreased, but the rate of A and D cells in the islets increased relatively in the remnant pancreas. 3) After resection of less than 63% of the fibrotic pancreas, secretion of both insulin and glucagon decreased temporarily with subsequent recovery. Diabetes did not develop. There were no marked morphological changes in the islets, nor significant changes in the distribution of B, A and D cells of the islets in the remnant pancreas. Diabetes developed after resection of more than 63% of the fibrotic pancreas 4 weeks after ligation of the pancreatic duct, while it developed after resection of more than 74% of the normal pancreas in dogs. Therefore, with regard to carbohydrate metabolism, resectability of the fibrotic pancreas was about 10% less than that of the normal pancreas in dogs.

Electrophysiological study of transport systems in isolated perfused pancreatic ducts: properties of the basolateral membrane

In order to study the mechanism of pancreatic HCO3- transport, a perfused preparation of isolated intra- and interlobular ducts (i.d. 20-40 microns) of rat pancreas was developed. Responses of the epithelium to changes in the bath ionic concentration and to addition of transport inhibitors was monitored by electrophysiological techniques. In this report some properties of the basolateral membrane of pancreatic duct cells are described. The transepithelial potential difference (PDte) in ducts bathed in HCO3(-)-free and HCO3(-)-containing solution was -0.8 and -2.6 mV, respectively. The equivalent short circuit current (Isc) under similar conditions was 26 and 50 microA . cm-2. The specific transepithelial resistance (Rte) was 88 omega cm2. In control solutions the PD across the basolateral membrane (PDbl) was -63 +/- 1 mV (n = 314). Ouabain (3 mmol/l) depolarized PDbl by 4.8 +/- 1.1 mV (n = 6) within less than 10 s. When the bath K+ concentration was increased from 5 to 20 mmol/l, PDbl depolarized by 15.9 +/- 0.9 mV (n = 50). The same K+ concentration step had no effect on PDbl if the ducts were exposed to Ba2+, a K+ channel blocker. Application of Ba2+ (1 mmol/l) alone depolarized PDbl by 26.4 +/- 1.4 mV (n = 19), while another K+ channel blocker TEA+ (50 mmol/l) depolarized PDbl only by 7.7 +/- 2.0 mV (n = 9). Addition of amiloride (1 mmol/l) to the bath caused 3-4 mV depolarization of PDbl. Furosemide (0.1 mmol/l) and SITS (0.1 mmol/l) had no effect on PDbl. An increase in the bath HCO3- concentration from 0 to 25 mmol/l produced fast and sustained depolarization of PDbl by 8.5 +/- 1.0 mV (n = 149). It was investigated whether the effect of HCO3- was due to a Na+-dependent transport mechanism on the basolateral membrane, where the ion complex transferred into the cell would be positively charged, or whether it was due to decreased K+ conductance caused by lowered intracellular pH. Experiments showed that the HCO3- effect was present even when the bath Na+ concentration was reduced to a nominal value of 0 mmol/l. Similarly, the HCO3- effect remained unchanged after Ba2+ (5 mmol/l) was added to the bath. The results indicate that on the basolateral membrane of duct cells there is a ouabain sensitive (Na+ + K+)-ATPase, a Ba2+ sensitive K+ conductance and an amiloride sensitive Na+/H+ antiport. The HCO3- effect on PDbl is most likely due to rheogenic anion exit across the luminal membrane.

Effect of K+ and K+ channel blockers on pancreatic HCO3-transport

The present study investigated whether there is a K+ conductive pathway on the basolateral membrane of pancreatic duct cells. Small inter- and intralobular ducts were isolated from rat pancreas and perfused in vitro. Duct cells were impaled and the potential across the basolateral membrane (PDbl) was measured. The resting potential was -61 +/- 1 mV. Ouabain (3 mmol/l) depolarized PDbl by 11 mV. Increase in the bath K+ concentration from 5 to 20 mmol/l depolarized PDbl by 15-16 mV. The effect of K+ channel blockers was tested. Ba2+ (1 mmol/l) added to the bath depolarized PDbl by 23-26 mV, whereas TEA+ (50 mmol/l) depolarized PDbl only by 7-8 mV. Dibutyryl cyclic AMP (0.5 mmol/l) depolarized PDbl by 20-30 mV. The results show that on the basolateral membrane of pancreatic duct cells there is a (Na+ + K+)-ATPase and a K+ conductive pathway sensitive to Ba2+.