Stimulation of pancreatic amylase release is associated with a parallel sustained increase of cytoplasmic calcium

The effects of Na+ on the in vitro release of amylase from mouse pancreas were studied. Replacement of Na+ in the medium by Tris, choline, or sucrose blocked the stimulation of amylase release by bethanechol and caerulein, whereas replacement by Li+ was without effect. The inhibiton was rapid and reversible, with stimulated amylase release linearly related to the log of the medium Na+ concentration over the range of 20-100 mM Na+. In contrast to the inhibition of amylase release stimulated by physiological secretagogues, enzyme release stimulated by the Ca2+ ionophore A23187 was unaffected by removal of Na+ from the medium. Tissue and intracellular Na+ and K+ contents were unchanged after stimulation of secretion by physiological stimulants. It is concluded that Na+ may be important in the early steps of stimulus-secretion coupling leading to the putative rise in intracellular Ca2+ that triggers pancreatic enzyme release.

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Cholinergic stimulation of pancreatic amylase release and muscarinic receptors: Effect of ionophore A23187

Life Sciences ◽

10.1016/0024-3205(85)90651-4 ◽

1985 ◽

Vol 37 (3) ◽

pp. 255-261 ◽

Cited By ~ 2

Author(s):

Louise Larose ◽

Jean Morisset

Keyword(s):

Muscarinic Receptors ◽

Ionophore A23187 ◽

Pancreatic Amylase ◽

Cholinergic Stimulation ◽

Amylase Release ◽

Stimulation Of

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Ca++ and pancreatic amylase release

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.228.6.1729 ◽

1975 ◽

Vol 228 (6) ◽

pp. 1729-1732 ◽

Cited By ~ 34

Author(s):

JA Williams ◽

D Chandler

Keyword(s):

Pancreatic Enzyme ◽

Enzyme Release ◽

Pancreatic Amylase ◽

Release Process ◽

Amylase Release ◽

Mouse Pancreas ◽

Cholinergic Agonist ◽

45Ca Efflux ◽

Total Tissue ◽

Stimulation Of

The effects of Ca'++ on release of amylase by mouse pancreas in vitri was studied.The cholinergic agonist bethanechol was depressed about 50% in O Ca'++ medium.When pancreatic fragments were superfused with O Ca'++ medium, bethanechol still produced a normal stimulation of amylase release after half of the total tissue Ca'++ was washed out. This Ca'++ loss included both extracellular and some intracellularCa'++. Uptake and equilibration of '45Ca'++ into pancreatic fragments was multiphasic, with total equilibration with stable Ca'++ still not reached after 3 h. Addition of bethanechol had no effect on the rate of '45Ca uptake and equilibration. '45Ca'++ efflux was not influenced by superfision in O Ca'++ medium, while thestimulation of '45Ca'++ efflux by bethanechol was enhanced. It is concluded that extracellular Ca'++ and/or Ca'++ influx is not of major importance in triggering pancreatic enzyme release, but that extracellular Ca'++ may regulate the release process thus accounting for the parallel changes in unstimulated and stimulated amylase release.

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Evaluation of Pancreatic Amylase mRNA upon Cholinergic Stimulation of Secretion

Journal of Histochemistry & Cytochemistry ◽

10.1177/002215540505300111 ◽

2005 ◽

Vol 53 (1) ◽

pp. 93-103 ◽

Cited By ~ 1

Author(s):

Diane Gingras ◽

Moïse Bendayan

Keyword(s):

Pancreatic Amylase ◽

Cholinergic Stimulation ◽

Stimulation Of

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Stimulation of vagal pulmonary C fibers by inhaled wood smoke in rats

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.1.30 ◽

1998 ◽

Vol 84 (1) ◽

pp. 30-36 ◽

Cited By ~ 59

Author(s):

C. J. Lai ◽

Y. R. Kou

Keyword(s):

Hydroxyl Radical ◽

Combined Treatment ◽

Wood Smoke ◽

Radical Scavenger ◽

C Fibers ◽

Hydroxyl Radical Scavenger ◽

C Fiber ◽

Delayed Phase ◽

Stimulation Of ◽

Sustained Increase

Lai, C. J., and Y. R. Kou. Stimulation of vagal pulmonary C fibers by inhaled wood smoke in rats. J. Appl. Physiol. 84(1): 30–36, 1998.—This study investigated the stimulation of vagal pulmonary C fibers (PCs) by wood smoke. We recorded impulses from PCs in 58 anesthetized, open-chest, and artificially ventilated rats and delivered 6 ml of wood smoke into the lungs. Within 1 or 2 s after the smoke delivery, an intense and nonphasic burst of discharge [Δ = +7.4 ± 0.7 (SE) impulses/s, n = 68] was evoked in 60 of the 68 PCs studied and lasted for 4–8 s. This immediate stimulation was usually followed by a delayed and more sustained increase in C-fiber activity (Δ = +2.0 ± 0.4 impulses/s). The overall stimulation was not influenced by removal of smoke particulates ( n = 15) or by pretreatment with vehicle ( n = 8) for dimethylthiourea (DMTU; a hydroxyl radical scavenger) or indomethacin (Indo; a cyclooxygenase inhibitor). The immediate-phase stimulation was not affected by pretreatment with Indo ( n= 8) but was largely attenuated by pretreatment with DMTU ( n = 12) or by a combined treatment with DMTU and Indo (DMTU+Indo; n = 8). Conversely, the delayed-phase stimulation was partially suppressed either by DMTU or by Indo but was totally abolished by DMTU+Indo. These results suggest that 1) the stimulation of PCs is linked to the gas phase of wood smoke and 2) hydroxyl radical, but not cyclooxygenase products, is involved in the immediate-phase stimulation, whereas both metabolites are responsible for evoking the delayed-phase stimulation.

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

Biochemical Journal ◽

10.1042/bj2350139 ◽

1986 ◽

Vol 235 (1) ◽

pp. 139-143 ◽

Cited By ~ 46

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.

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Calcium fluxes in isolated pancreatic acini: effects of secretagogues

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1981.240.1.g38 ◽

1981 ◽

Vol 240 (1) ◽

pp. G38-G49 ◽

Cited By ~ 1

Author(s):

R. L. Dormer ◽

J. H. Poulsen ◽

V. Licko ◽

J. A. Williams

Keyword(s):

Time Course ◽

Calcium Content ◽

Total Calcium ◽

Good Correspondence ◽

Amylase Release ◽

Pancreatic Acini ◽

Kinetic Component ◽

Rapid Drop ◽

Single Exponential ◽

Stimulation Of

45Ca2+ exchange and total calcium content were measured in isolated mouse pancreatic acini. 45Ca2+ uptake could be described as the sum of a constant and a single exponential kinetic component; about 60% of total acinar calcium was exchangeable. Stimulation by bethanechol increased 45Ca2+ uptake, but the time course of uptake could be fit only by the addition of a more rapid kinetic component without any change in the total exchangeable Ca2+. 45Ca2+ washout after 1-h loading could be fit as the sum of two exponential components. Stimulation increased the rate of 45Ca2+ washout with the appearance of a third and more rapid kinetic component. There was not, however, a good correspondence between the exponential constants measured in uptake and washout protocols in unstimulated acini. Exponential constants were also affected by the concentration of calcium in the medium, further indicating the presence of nonlinearities in 45Ca2+ exchange. The dose-response relationships were similar for bethanechol stimulation of 45Ca2+ uptake and amylase release, whereas stimulation of 45Ca2+ washout reached a maximum at a higher concentration of bethanechol. Both 45Ca2+ uptake and analytical measurement of total Ca2+ showed a rapid drop in acinar Ca2+ content followed by a gradual reuptake on stimulation by bethanechol. It is concluded that the initial primary effect of secretagogues is to increase Ca2+ efflux, which is interpreted to be the result of release of sequestered calcium into the cytosol.

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A new CCK analogue differentiates two functionally distinct CCK receptors in rat and mouse pancreatic acini

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.257.4.g594 ◽

1989 ◽

Vol 257 (4) ◽

pp. G594-G600 ◽

Cited By ~ 5

Author(s):

T. Matozaki ◽

J. Martinez ◽

J. A. Williams

Keyword(s):

Competitive Inhibition ◽

Inhibitory Effect ◽

Leucine Incorporation ◽

Amylase Release ◽

Pancreatic Acini ◽

Cck Receptors ◽

Partial Agonists ◽

Low Concentrations ◽

Phenylalanine Residue ◽

Stimulation Of

Analysis of the competitive inhibition of 125I-labeled cholecystokinin octapeptide (CCK-8) binding to isolated rat or mouse pancreatic acini showed that in both species CCK-8 interacts with two different affinity sites. A newly synthesized CCK analogue modified at the COOH-terminal phenylalanine residue totally inhibited 125I-CCK binding. This interaction occurred with sites of a single affinity in rat acini but with two different affinity sites in mouse acini. When acini were incubated with increasing concentrations of CCK-8, a biphasic stimulation of amylase release was observed. By use of rat acini, the analogs stimulated amylase release but caused no inhibition at supramaximal concentrations. By contrast, in mouse pancreatic acini, analogues showed a biphasic stimulation of amylase release similar to CCK-8. Both CCK-8 and the analogue stimulated [3H]leucine incorporation into protein at low concentrations in rat pancreatic acini. Higher concentrations of CCK-8 profoundly inhibited [3H]leucine incorporation, whereas the analogue had no inhibitory effect. Moreover, the analogue at higher concentrations blocked the inhibition of [3H]leucine incorporation caused by CCK-8 but did not affect carbamylcholine-induced inhibition. In mouse acini, however, the CCK analogue inhibited [3H]leucine incorporation similar to the effect of CCK-8. The results support the concept that occupancy of distinct affinity sites or states of the CCK receptor is associated with specific biological actions. A model of the CCK receptor is proposed in which two interchangeable affinity states exist. By occupying all the receptors in only one state, the new CCK analogues serve as partial agonists of some and antagonists of other actions of CCK.

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