Endocrine secretion of alpha-amylase by the pancreas

1981 ◽  
Vol 241 (2) ◽  
pp. G170-G175 ◽  
Author(s):  
K. Miyasaka ◽  
S. S. Rothman
Keyword(s):  
Acinar Cell ◽  
Digestive Enzyme ◽  
Alpha Amylase ◽  
Gastrointestinal Hormone ◽  
Amylase Secretion ◽  
Amylase Release ◽  
Applied Dose ◽  
Rabbit Pancreas ◽  
Order Of Magnitude ◽  
Endocrine Secretion

The effect of the gastrointestinal hormone, cholecystokinin-pancreozymin (CCK-PZ), on the flux of alpha-amylase across the basolateral surface of the pancreas into interstitial fluid was measured by following its appearance in the medium bathing whole rabbit pancreas in organ culture. CCK-PZ increased the rate of amylase release by about an order of magnitude for the maximum applied dose. The response was only observed at concentrations of CCK-PZ that were supramaximal for ductal enzyme secretion (320 pmol/l to 10 nmol/l). Over this range, amylase secretion into the bath varied widely with dose, whereas that into the duct remained relatively unchanged. These observations, in conjunction with others, suggest that the acinar cell, and not the duct system, is the direct source of this amylase and that there is a natural secretion of digestive enzyme from the acinar cell in the endocrine direction that is augmented by CCK-PZ or a homologous peptide.

Effects of staurosporine on protein kinase C and amylase secretion from pancreatic acini

1989 ◽  
Vol 257 (4) ◽  
pp. G548-G553 ◽  
Author(s):  
T. B. Verme ◽  
R. T. Velarde ◽  
R. M. Cunningham ◽  
S. R. Hootman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Digestive Enzyme ◽  
Amylase Secretion ◽  
Ionophore A23187 ◽  
Functional Protein ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Kinase C ◽  
Protein Kinase C Activity

The effects of staurosporine, a recently isolated microbial alkaloid, on amylase secretion and protein kinase C activity of guinea pig pancreatic acini were investigated. Staurosporine at a concentration of 1 microM completely inhibited both acinar protein kinase C activity (IC50 = 5.5 +/- 1.4 nM) and amylase secretion induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (IC50 = 4.1 +/- 0.4 nM). At this concentration, staurosporine reduced amylase secretion elicited by maximally effective concentrations of carbachol and cholecystokinin by approximately 50% but did not appreciably alter the potencies of the two secretagogues. In the presence of staurosporine, amylase secretion induced by carbachol was linear for at least 60 min. Staurosporine had no effect on amylase release elicited by the Ca2+ ionophore A23187. It did, however, inhibit secretion induced by vasoactive intestinal peptide, although with a reduced potency relative to its effects on amylase release stimulated by TPA, carbachol, and cholecystokinin (IC50 = 34 +/- 17 nM). These results indicate that staurosporine is a potent inhibitor of protein kinase C activity in pancreatic acini and that protein kinase C has an important role as an intracellular mediator of digestive enzyme secretion induced by cholecystokinin and carbachol in the acinar cell. In addition, a separate staurosporine-insensitive coupling pathway, most likely involving Ca2+, appears to be equally important and can maintain long-term secretion in the absence of functional protein kinase C activity.

Glutathione depletion inhibits amylase release in guinea pig pancreatic acini

1983 ◽  
Vol 244 (3) ◽  
pp. G273-G277
Author(s):  
W. F. Stenson ◽  
E. Lobos ◽  
H. J. Wedner
Keyword(s):  
Guinea Pig ◽  
Reduced Glutathione ◽  
Glutathione Depletion ◽  
Amylase Secretion ◽  
Ionophore A23187 ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Stimulus Secretion Coupling ◽  
Dose Dependent ◽  
Higher Doses

Isolated guinea pig pancreatic acini were specifically depleted of glutathione by treatment with 2-cyclohexene-1-one (2-CHX-1). Untreated acini contained 4.3 +/- 0.6 micrograms of glutathione per milligram protein. Incubation with 1 mM 2-CHX-1 for 5 min at 37 degrees C depleted glutathione to 17% of control values; 5 mM 2-CHX-1 depleted glutathione to less than 4% of control values. Incubation with 2-CHX-1 also impaired the ability of the isolated acini to secrete amylase in response to stimulation with carbachol and the ionophore A23187. The depletion of glutathione and the inhibition of amylase secretion by 2-CHX-1 were both dose dependent and time dependent. Incubation of acini with 2 mM 2-CHX-1 for 15 min at 37 degrees C reduced glutathione levels to 6.6% of control and reduced carbachol-stimulated amylase release to 63% of control. Higher doses of 2-CHX-1 or longer incubations resulted in greater depletion of glutathione and greater inhibition of carbachol-induced amylase release. These data indicate that specific depletion of glutathione impairs the ability of isolated acini to secrete amylase in response to physiological and pharmacologic stimuli and suggest that glutathione has a role in stimulus-secretion coupling in the exocrine pancreas.

Chewing bread: impact on alpha-amylase secretion and oral digestion

2017 ◽  
Vol 8 (2) ◽  
pp. 607-614 ◽  
Author(s):  
Marianne Joubert ◽  
Chantal Septier ◽  
Hélène Brignot ◽  
Christian Salles ◽  
Maud Panouillé ◽  
...  
Keyword(s):  
Alpha Amylase ◽  
Amylase Secretion ◽  
Food Bolus

During chewing, saliva helps in preparing the food bolus by agglomerating the formed particles, and it initiates enzymatic food breakdown.

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.

scholarly journals Functional role of J domain of cysteine string protein in Ca2+-dependent secretion from acinar cells

2009 ◽  
Vol 296 (5) ◽  
pp. G1030-G1039 ◽  
Author(s):  
Ning Weng ◽  
Megan D. Baumler ◽  
Diana D. H. Thomas ◽  
Michelle A. Falkowski ◽  
Leigh Anne Swayne ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Secretory Pathway ◽  
Digestive Enzyme ◽  
Family Members ◽  
Protective Role ◽  
Amylase Secretion ◽  
Zymogen Granule ◽  
Hsp70 Family ◽  
Cysteine String Protein ◽  
J Domain

The heat shock protein 70 family members Hsc70 and Hsp70 are known to play a protective role against the onset of experimental pancreatitis, yet their molecular function in acini is unclear. Cysteine string protein (CSP-α) is a zymogen granule (ZG) membrane protein characterized by an NH2-terminal “J domain” and a central palmitoylated string of cysteine residues. The J domain functions as a cochaperone by modulating the activity of Hsc70/Hsp70 family members. A role for CSP-α in regulating digestive enzyme exocytosis from pancreas was investigated by introducing CSP-α truncations into isolated acini following their permeabilization with Perfringolysin O. Incubation of acini with CSP-α1-82, containing the J domain, significantly augmented Ca2+-stimulated amylase secretion. Effects of CSP-α1-82 were concentration dependent, with a maximum 80% increase occurring at 200 μg/ml of protein. Although CSP-α1-82 had no effects on basal secretion measured in the presence of ≤10 nM free Ca2+, it did significantly augment GTP-γS-induced secretion under basal Ca2+ conditions by ∼25%. Mutation of the J domain to abolish its cochaperone activity failed to augment Ca2+-stimulated secretion, implicating the CSP-α/Hsc70 cochaperone system as a regulatory component of the secretory pathway. CSP-α physically associates with vesicle-associated membrane protein 8 (VAMP 8) on ZGs, and the CSP-α-VAMP 8 interaction was dependent on amino acids 83-112 of CSP-α. Immunofluorescence analysis of acinar lobules or purified ZGs confirmed the CSP-α colocalization with VAMP 8. These data establish a role for CSP-α in regulating digestive enzyme secretion and suggest that CSP-α and Hsc70 modulate specific soluble N-ethylmaleimide-sensitive attachment receptor interactions necessary for exocytosis.

Amylase secretion by isolated pancreatic acini after acute cholecystokinin treatment in vivo

1984 ◽  
Vol 246 (4) ◽  
pp. G419-G425 ◽  
Author(s):  
M. Otsuki ◽  
Y. Okabayashi ◽  
A. Ohki ◽  
S. R. Hootman ◽  
S. Baba ◽  
...  
Keyword(s):  
Binding Sites ◽  
Amylase Secretion ◽  
Response Curves ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Cholecystokinin Receptor ◽  
Isolated Pancreatic Acini ◽  
And Control ◽  
Quinuclidinyl Benzilate

A single dose of synthetic cholecystokinin octapeptide (CCK8, 5 micrograms/kg) in a depot carrier was injected subcutaneously into rats 2 and 14 h before the removal of the pancreas and the preparation of isolated pancreatic acini. CCK8 treatment induced no significant change in body weight or total amount of pancreatic DNA, but pancreatic weight, total pancreatic protein and amylase, and the concentration of amylase and total protein relative to DNA were significantly decreased. In acini prepared from CCK8-pretreated rats, responsiveness to maximal and supramaximal concentrations of CCK8 was significantly increased, irrespective of whether the amount of amylase released was expressed relative to DNA or calculated as a percentage of the acinar content. The dose-response curves for CCK8 were similarly shaped in both CCK8-pretreated and control rats but shifted threefold toward higher concentrations of CCK8 2 or 14 h after CCK8 treatment. Specific 125I-CCK binding was significantly increased only for high-affinity binding sites. Although these observations suggest that alterations in pancreatic amylase release could be due to changes at the cholecystokinin receptor, the secretory responsiveness to maximal and supramaximal concentrations of carbachol was also increased without any change in the sensitivity. Moreover, in contrast to the cholecystokinin receptor, there was no change in the number of muscarinic receptors or in their affinity for either agonists or antagonists measured with [3H]quinuclidinyl benzilate.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Caerulein and carbamoylcholine stimulate pancreatic amylase release at resting cytosolic free Ca2+

1986 ◽  
Vol 235 (1) ◽  
pp. 139-143 ◽  
Author(s):  
R Bruzzone ◽  
T Pozzan ◽  
C B Wollheim
Keyword(s):  
Fold Increase ◽  
Free Calcium ◽  
Amylase Secretion ◽  
Rapid Phase ◽  
Secretory Rate ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Significant Stimulation ◽  
Phase 0 ◽  
Stimulation Of

Cytosolic free calcium concentrations ([Ca2+]i) and amylase secretion were measured in isolated rat pancreatic acini loaded with the intracellularly trapped fluorescent indicator quin2. Both caerulein and carbamoylcholine caused a rapid increase in [Ca2+]i, with a maximal 3-fold increase at 10(-9) M-caerulein and 10(-4) M-carbamoylcholine. However, caerulein (10(-12) M and 10(-11) M) as well as carbamoylcholine (10(-7) M) caused a significant stimulation of amylase release, while not inducing any detectable rise in [Ca2+]i. Changes in [Ca2+]i after addition of either secretagogue were transient and did not last more than 2-3 min. By contrast, when amylase secretion was monitored as a function of time, two distinct secretory phases could be observed upon addition of either carbamoylcholine (10(-5) M) or caerulein (10(-10) M). An initial, rapid phase (0-5 min) which caused a 6-7-fold increase above basal, followed by a sustained (5-30 min), but less marked, secretory rate (2-3-fold above basal). Addition of atropine (10(-4) M) 5 min after carbamoylcholine (10(-5) M) (i.e. after termination of the rise in [Ca2+]i and of the first secretory phase) did not cause any significant change in [Ca2+]i, while significantly inhibiting amylase secretion from 5 to 30 min to the same rate observed in the absence of the secretagogue. These results show that caerulein and carbamoylcholine, two agents thought to activate secretion mainly through mobilization of Ca2+ from intracellular stores, are capable of eliciting amylase secretion independently of a concomitant rise in [Ca2+]i. Furthermore, with both secretagogues the rise in [Ca2+]i, when observed, was only transient, while the stimulation of amylase release was sustained.

scholarly journals Jasmonate-independent regulation of digestive enzyme activity in the carnivorous butterwort Pinguicula × Tina

2020 ◽  
Vol 71 (12) ◽  
pp. 3749-3758 ◽  
Author(s):  
Ondřej Kocáb ◽  
Jana Jakšová ◽  
Ondřej Novák ◽  
Ivan Petřík ◽  
René Lenobel ◽  
...  
Keyword(s):  
Jasmonic Acid ◽  
Enzyme Activities ◽  
Digestive Enzymes ◽  
Defense Mechanisms ◽  
Prey Capture ◽  
Digestive Enzyme ◽  
Carnivorous Plants ◽  
Alpha Amylase ◽  
Jasmonate Signaling ◽  
Digestive Enzyme Activities

Abstract Carnivorous plants within the order Caryophyllales use jasmonates, a class of phytohormone, in the regulation of digestive enzyme activities. We used the carnivorous butterwort Pinguicula × Tina from the order Lamiales to investigate whether jasmonate signaling is a universal and ubiquitous signaling pathway that exists outside the order Caryophyllales. We measured the electrical signals, enzyme activities, and phytohormone tissue levels in response to prey capture. Mass spectrometry was used to identify proteins in the digestive secretion. We identified eight enzymes in the digestive secretion, many of which were previously found in other genera of carnivorous plants. Among them, alpha-amylase is unique in carnivorous plants. Enzymatic activities increased in response to prey capture; however, the tissue content of jasmonic acid and its isoleucine conjugate remained rather low in contrast to the jasmonate response to wounding. Enzyme activities did not increase in response to the exogenous application of jasmonic acid or coronatine. Whereas similar digestive enzymes were co-opted from plant defense mechanisms among carnivorous plants, the mode of their regulation differs. The butterwort has not co-opted jasmonate signaling for the induction of enzyme activities in response to prey capture. Moreover, the presence of alpha-amylase in digestive fluid of P. × Tina, which has not been found in other genera of carnivorous plants, might indicate that non-defense-related genes have also been co-opted for carnivory.

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