BAY-K-8644-stimulated amylase secretion from pancreatic acinar cells

1988 ◽  
Vol 66 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Seymour Heisler ◽  
Diane Desjardins ◽  
Marthe Belles-Isles
Keyword(s):  
Calcium Channel ◽  
Acinar Cell ◽  
Acinar Cells ◽  
Secretory Response ◽  
Bay K 8644 ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Calcium Channel Antagonists ◽  
Calcium Channel Activator ◽  
Cgmp Synthesis

Pancreatic acinar cells do not contain depolarization-sensitive calcium channels. Nonetheless, in the current study, the calcium channel activator, BAY-K-8644, was found to stimulate a time- and concentration-dependent increase in the spontaneous release of amylase. Secretion was dependent on the presence of extracellular calcium in the incubation medium. Racemic BAY-K-8644 and (or) its S(−)optical isomer did not enhance the secretory response to either carbachol or cholecystokinin octapeptide; however, when co-applied with either phorbol ester, vasoactive intestinal peptide, or forskolin, they potentiated amylase secretion. Nifedipine and the R(+)isomer of BAY-K-8644, which are both calcium channel antagonists, did not alter basal or forskolin-stimulated amylase secretion, and [3H]nitrendipine did not bind to acinar cell membranes. Neither atropine nor dibutyryl cGMP, inhibitors of cholinergic and cholecystokininergic receptors, respectively, affected BAY-K-8644-induced amylase secretion. While BAY-K-8644 stimulated concentration-dependent cGMP synthesis in acinar cells, it had no effect on basal or forskolin-stimulated cAMP formation. The data suggest that BAY-K-8644 may bind to acinar cell sites that are not functional calcium channel proteins but are coupled nevertheless to the secretory response, and that calcium channel antagonists do not bind to these sites. The mechanism of the secretagogue action of BAY-K-8644 remains to be elucidated.

scholarly journals Enhanced Secretion of Amylase from Exocrine Pancreas of Connexin32-deficient Mice

1998 ◽  
Vol 141 (5) ◽  
pp. 1267-1275 ◽  
Author(s):  
Marc Chanson ◽  
Marjorie Fanjul ◽  
Domenico Bosco ◽  
Eric Nelles ◽  
Susanne Suter ◽  
...  
Keyword(s):  
Acinar Cell ◽  
Intercellular Communication ◽  
Plaque Assay ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Wild Type ◽  
Patch Clamp Recording ◽  
Junctional Communication

To determine whether junctional communication between pancreatic acinar cells contributes to their secretory function in vivo, we have compared wild-type mice, which express the gap junctional proteins connexin32 (Cx32) and connexin26, to mice deficient for the Cx32 gene. Pancreatic acinar cells from Cx32 (−/−) mice failed to express Cx32 as evidenced by reverse transcription–PCR and immunolabeling and showed a marked reduction (4.8- and 25-fold, respectively) in the number and size of gap junctions. Dye transfer studies showed that the extent of intercellular communication was inhibited in Cx32 (−/−) acini. However, electrical coupling was detected by dual patch clamp recording in Cx32 (−/−) acinar cell pairs. Although wild-type and Cx32 (−/−) acini were similarly stimulated to release amylase by carbamylcholine, Cx32 (−/−) acini showed a twofold increase of their basal secretion. This effect was caused by an increase in the proportion of secreting acini, as detected with a reverse hemolytic plaque assay. Blood measurements further revealed that Cx32 (−/−) mice had elevated basal levels of circulating amylase. The results, which demonstrate an inverse relationship between the extent of acinar cell coupling and basal amylase secretion in vivo, support the view that the physiological recruitment of secretory acinar cells is regulated by gap junction mediated intercellular communication.

scholarly journals Cholecystokinin octapeptide inhibits Ca2+-dependent amylase secretion from permeabilized pancreatic acini by blocking the MgATP-dependent priming of exocytosis

1998 ◽  
Vol 330 (1) ◽  
pp. 329-334 ◽  
Author(s):  
J. Philip PADFIELD ◽  
Ninder PANESAR
Keyword(s):  
Acinar Cells ◽  
Secretory Response ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Rapid Phase ◽  
Pancreatic Acini ◽  
Cholecystokinin Octapeptide ◽  
Cholecystokinin Receptor ◽  
Specific Antagonist

At present little is known about how the low-affinity cholecystokinin receptor inhibits secretagogue-stimulated amylase secretion from pancreatic acinar cells. To examine this question we have determined how cholecystokinin octapeptide (CCK8) influences Ca2+-dependent amylase secretion from α-toxin-permeabilized pancreatic acini. CCK8 significantly inhibited Ca2+-stimulated amylase secretion. The inhibitory actions of CCK8 were completely blocked by the addition of JMV-180, a specific antagonist for the low-affinity CCK8 receptor. Previous studies have shown that Ca2+-dependent amylase secretion from α-toxin-permeabilized acini has two distinct phases [Padfield and Panesar (1997) Am. J. Physiol. 36, G655-660]. There is an initial rapid phase of secretion which represents release from exocytotic sites primed by MgATP prior to permeabilization. This is followed by a slower sustained phase of secretion which, in part, reflects the MgATP-dependent repriming of the exocytotic machinery. CCK8 did not influence the initial rapid phase of the Ca2+-dependent secretory response, but inhibited the second slower sustained phase. Moreover, CCK8 was shown to inhibit the MgATP-dependent priming of exocytosis in the acini. These results indicate that the low-affinity CCK receptor blocks stimulated amylase secretion by inhibiting the MgATP-dependent repriming of exocytosis.

Calmodulin antagonists inhibit dihydropyridine calcium channel activator (BAY-K-8644) induced cGMP synthesis in pituitary tumor cells

1986 ◽  
Vol 64 (6) ◽  
pp. 760-763 ◽  
Author(s):  
Seymour Heisler
Keyword(s):  
Calcium Channel ◽  
Bay K 8644 ◽  
Dependent Manner ◽  
Calmodulin Antagonists ◽  
Concentration Dependent Manner ◽  
Calcium Channel Activator ◽  
Cgmp Formation ◽  
Cgmp Synthesis ◽  
Channel Activator

The dihydropyridine calcium channel activator, BAY-K-8644, stimulates cGMP formation in ACTH-secreting mouse AtT-20 clonal corticotrophs. The recent report that calmodulin antagonists could inhibit dihydropyridine binding in several tissues suggested that these agents might also affect the cyclic nucleotide response to BAY-K-8644. In fact, TMB-8, trifluoperazine, and melittin, described as in vitro antagonists of calmodulin-dependent enzyme activities, all inhibited BAY-K-8644 induced cGMP synthesis in a concentration-dependent manner. The antagonists had no effect on cGMP formation stimulated by sodium nitroprusside or sodium azide. The calcium channel antagonist, nifedipine, did not stimulate cGMP formation nor did it alter the effect of BAY-K-8644 on accumulation of the nucleotide; one explanation thus is that the cyclase involved in cGMP formation is coupled to a low affinity binding site for BAY-K-8644, which is less accessible to other dihydropyridines. The relation of cyclic GMP formation to the function of the calcium channel in AtT-20 cells remains unknown.

Forskolin potentiates calcium-dependent amylase secretion from rat pancreatic acinar cells

1983 ◽  
Vol 61 (10) ◽  
pp. 1168-1176 ◽  
Author(s):  
Seymour Heisler
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Acinar Cells ◽  
Secretory Response ◽  
Pancreatic Acinar Cells ◽  
Secretory Process ◽  
Amylase Secretion ◽  
Primary Role ◽  
Amylase Release ◽  
Calcium Dependent

The cellular and molecular effects of forskolin, a direct, nonhormonal activator of adenylate cyclase, were assessed on the enzyme secretory process in dispersed rat pancreatic acinar cells. Forskolin stimulated adenylate cyclase activity in the absence of guanyl nucleotide. It promoted a rapid and marked increase in cellular accumulation of cyclic AMP alone or in combination with vasoactive intestinal peptide (VIP) but was itself a weak pancreatic agonist and did not increase the secretory response to VIP or other cyclic AMP dependent agonists. Somatostatin was a partial antagonist of forskolin stimulated cyclic AMP synthesis and forskolin plus cholecystokinin-octapeptide (CCK-OP) induced amylase release. Forskolin potentiated amylase secretion in response to calcium-dependent agonists such as CCK-OP, carbachol and A-23187, but did not affect the ability of CCK-OP and (or) carbachol to mobilize 45Ca from isotope preloaded cells; forskolin alone did not stimulate 45Ca release. In calcium-poor media, the secretory response to forskolin and CCK-OP was reduced in a both absolute and relative manner. The data suggests that calcium plays the primary role as intracellular mediator of enzyme secretion and that the role of cyclic AMP may be to modulate the efficiency of calcium utilization.

scholarly journals Dietary-induced changes in the fatty acid profile of rat pancreatic membranes are associated with modifications in acinar cell function and signalling

2004 ◽  
Vol 91 (2) ◽  
pp. 227-234 ◽  
Author(s):  
Maria D. Yago ◽  
Ricardo J. Diaz ◽  
Rolando Ramirez ◽  
Maria A. Martinez ◽  
Mariano Mañas ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Acinar Cell ◽  
Cell Function ◽  
Acinar Cells ◽  
Dietary Lipids ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Pancreatic Cell ◽  
Pancreatic Acini

The effects of dietary lipids on the fatty acid composition of rat pancreatic membranes and acinar cell function were investigated. Weaning rats were fed for 8 weeks on one of two diets which contained 100 g virgin olive oil (OO) or sunflowerseed oil (SO)/kg. Pancreatic plasma membranes were isolated and fatty acids determined. Amylase secretion and cytosolic concentrations of Ca2+and Mg2+were measured in pancreatic acini. Membrane fatty acids were profoundly affected by the diets; the rats fed OO had higher levels of 18:1n-9 (42·86 (sem 1·99) %) and total MUFA compared with the animals fed SO (25·37 (sem 1·11) %). Reciprocally, the SO diet resulted in greater levels of total andn-6 PUFA than the OO diet. The most striking effect was observed for 18:2n-6 (SO 17·88 (sem 1·32) %; OO 4·45 (sem 0·60) %), although the levels of 20:4n-6 were also different. The proportion of total saturated fatty acids was similar in both groups, and there was only a slight, not significant (P=0·098), effect on the unsaturation index. Compared with the OO group, acinar cells from the rats fed SO secreted more amylase at rest but less in response to cholecystokinin octapeptide, and this was paralleled by reduced Ca2+responses to the secretagogue. The results confirm that rat pancreatic cell membranes are strongly influenced by the type of dietary fat consumed and this is accompanied by a modulation of the secretory activity of pancreatic acinar cells that involves, at least in part, Ca2+signalling.

scholarly journals Inhibitory effect of high leucine concentration on α-amylase secretion by pancreatic acinar cells: possible key factor of proteasome

2018 ◽  
Vol 38 (6) ◽  
Author(s):  
Long Guo ◽  
Baolong Liu ◽  
Chen Zheng ◽  
Hanxun Bai ◽  
Hao Ren ◽  
...  
Keyword(s):  
Amylase Activity ◽  
Acinar Cells ◽  
Inhibitory Effect ◽  
Proteasome Activity ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
High Concentration ◽  
Amylase Release ◽  
Cholecystokinin Receptor ◽  
Key Factor

The present study aimed to investigate whether leucine affects the pancreatic exocrine by controlling the antisecretory factor (AF) and cholecystokinin receptor (CCKR) expression as well as the proteasome activity in pancreatic acinar cells of dairy calves. The pancreatic acinar cells were isolated from newborn Holstein bull calves and cultured using the Dulbecco’s modified Eagle’s medium/nutrient mixture F12 Ham’s liquid (DMEM/F12). There were six treatments of leucine dosage including 0 (control), 0.23, 0.45, 1.35, 4.05, and 12.15 mM, respectively. After culture for 3 h, the samples were collected for subsequent analysis. As the leucine concentration increased from 0 to 1.35 mM, the α-amylase activity in media decreased significantly (P<0.05), while further increase in leucine concentration did not show any decrease in α-amylase activity. Addition of leucine inhibited (P<0.05) the expression of AF and CCKR, and decreased the activity of proteasome (P<0.05) by 76%, 63%, 24%, 7%, and 9%, respectively. Correlation analysis results showed α-amylase secretion was negatively correlated with leucine concentration (P<0.01), and positively correlated with proteasome activity (P<0.01) and the expression of CCK1R (P<0.01) and AF (P<0.05). The biggest regression coefficient was showed between α-amylase activity and proteasome (0.7699, P<0.001). After inhibition of proteasome by MG-132, low dosage leucine decreased (P<0.05) the activity of proteasome and α-amylase, as well as the expression of CCK1R. In conclusion, we demonstrated that the high-concentration leucine induced decrease in α-amylase release was mainly by decreasing proteasome activity.

Regulation of CCK-induced amylase release by PKC-δ in rat pancreatic acinar cells

2004 ◽  
Vol 287 (4) ◽  
pp. G764-G771 ◽  
Author(s):  
Chenwei Li ◽  
Xuequn Chen ◽  
John A. Williams
Keyword(s):  
Acinar Cells ◽  
Adenoviral Vectors ◽  
Dominant Negative ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Wild Type ◽  
Amylase Release ◽  
Pkc Isoforms ◽  
Chemical Inhibitors ◽  
Dominant Negative Variant

PKC is known to be activated by pancreatic secretagogues such as CCK and carbachol and to participate along with calcium in amylase release. Four PKC isoforms, α, δ, ε, and ζ, have been identified in acinar cells, but which isoforms participate in amylase release are unknown. To identify the responsible isoforms, we used translocation assays, chemical inhibitors, and overexpression of individual isoforms and their dominant-negative variants by means of adenoviral vectors. CCK stimulation caused translocation of PKC-α, -δ, and -ε, but not -ζ from soluble to membrane fraction. CCK-induced amylase release was inhibited ∼30% by GF109203X, a broad spectrum PKC inhibitor, and by rottlerin, a PKC-δ inhibitor, but not by Gö6976, a PKC-α inhibitor, at concentrations from 1 to 5 μM. Neither overexpression of wild-type or dominant-negative PKC-α affected CCK-induced amylase release. Overexpression of PKC-δ and -ε enhanced amylase release, whereas only dominant-negative PKC-δ inhibited amylase release by 25%. PKC-δ overexpression increased amylase release at all concentrations of CCK, but dominant-negative PKC-δ only inhibited the maximal concentration; both similarly affected carbachol and JMV-180-induced amylase release. Overexpression of both PKC-δ and its dominant-negative variant affected the late but not the early phase of amylase release. GF109203X totally blocked the enhancement of amylase release by PKC-δ but had no further effect in the presence of dominant-negative PKC-δ. These results indicate that PKC-δ is the PKC isoform involved with amylase secretion.

Crambene induces pancreatic acinar cell apoptosis via the activation of mitochondrial pathway

2006 ◽  
Vol 291 (1) ◽  
pp. G95-G101 ◽  
Author(s):  
Yang Cao ◽  
Sharmila Adhikari ◽  
Abel Damien Ang ◽  
Marie Véronique Clément ◽  
Matthew Wallig ◽  
...  
Keyword(s):  
Acinar Cell ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Fas Ligand ◽  
Annexin V ◽  
Acinar Cells ◽  
Mitochondrial Pathway ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Pancreatic Acini

We investigated the apoptotic pathway activated by crambene (1-cyano-2-hydroxy-3-butene), a plant nitrile, on pancreatic acinar cells. As evidenced by annexin V-FITC staining, crambene treatment for 3 h induced the apoptosis but not necrosis of pancreatic acini. Caspase-3, -8, and -9 activities in acini treated with crambene were significantly higher than in untreated acini. Treatment with caspase-3, -8, and -9 inhibitors inhibited annexin V staining, as well as caspase-3 activity, pointing to an important role of these caspases in crambene-induced acinar cell apoptosis. The mitochondrial membrane potential was collapsed, and cytochrome c was released from the mitochondria in crambene-treated acini. Neither TNF-α nor Fas ligand levels were changed in pancreatic acinar cells after crambene treatment. These results provide evidence for the induction of pancreatic acinar cell apoptosis in vitro by crambene and suggest the involvement of mitochondrial pathway in pancreatic acinar cell apoptosis.

scholarly journals CaMKII/proteasome/cytosolic calcium/cathepsin B axis was present in tryspin activation induced by nicardipine

2019 ◽  
Vol 39 (7) ◽  
Author(s):  
Juan Xiao ◽  
Houmin Lin ◽  
Binggang Liu ◽  
Junfei Jin
Keyword(s):  
Acute Pancreatitis ◽  
Calcium Channel ◽  
Cathepsin B ◽  
Acinar Cells ◽  
Proteasome Inhibition ◽  
Cytosolic Calcium ◽  
Pancreatic Acinar Cells ◽  
Prolonged Treatment ◽  
Early Event ◽  
Trypsinogen Activation

Abstract Premature trypsinogen activation is the early event of acute pancreatitis. Therefore, the studies on the processes of trypsinogen activation induced by compounds are important to understand mechanism underly acute pancreatitis under various conditions. Calcium overload in the early stage of acute pancreatitis was previously found to cause intracellular trypsinogen activation; however, treatment of acute pancreatitis using calcium channel blockers did not produced consistent results. Proteasome activity that could be inhibited by some calcium channel blocker has recently been reported to affect the development of acute pancreatitis; however, the associated mechanism were not fully understood. Here, the roles of nicardipine were investigated in trypsinogen activation in pancreatic acinar cells. The results showed that nicardipine could increase cathepsin B activity that caused trypsinogen activation, but higher concentration of nicardipine or prolonged treatment had an opposite effect. The effects of short time treatment of nicardipine at low concentration were studied here. Proteasome inhibition was observed under nicardipine treatment that contributed to the up-regulation in cytosolic calcium. Increased cytosolic calcium from ER induced by nicardipine resulted in the release and activation of cathepsin B. Meanwhile, calcium chelator inhibited cathepsin B as well as trypsinogen activation. Consistently, proteasome activator protected acinar cells from injury induced by nicardipine. Moreover, proteasome inhibition caused by nicardipine depended on CaMKII. In conclusion, CaMKII down-regulation/proteasome inhibition/cytosolic calcium up-regulation/cathepsin B activation/trypsinogen activation axis was present in pancreatic acinar cells injury under nicardipine treatment.

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