Caerulein causes translocation of protein kinase C in rat acini without increasing cytosolic free Ca2+

Details

Serval ID
serval:BIB_D0B259B05182
Type
Article: article from journal or magazin.
Collection
Publications
Title
Caerulein causes translocation of protein kinase C in rat acini without increasing cytosolic free Ca2+
Journal
American Journal of Physiology
Author(s)
Bruzzone  R., Regazzi  R., Wollheim  C. B.
ISSN
0002-9513 (Print)
0193-1857
ISSN-L
0193-1857
Publication state
Published
Issued date
07/1988
Volume
255
Number
1 Pt 1
Pages
G33-9
Notes
In Vitro Journal Article Research Support, Non-U.S. Gov't --- Old month value: Jul
Abstract
We investigated the relationships between changes in cytosolic free Ca2+ ([Ca2+]i) and amylase secretion in dispersed rat pancreatic acini. Although 10 pM caerulein did not raise [Ca2+]i, higher concentrations (1 nM) of the peptide elicited a prompt, marked, but transient (2-3 min) elevation of [Ca2+]i. Both concentrations of caerulein caused an almost identical release of amylase over a 30-min period. To investigate the mechanism(s) underlying Ca2+-independent secretion, we measured the effect of the secretagogue on protein kinase C activity and found that both caerulein concentrations caused a significant translocation of protein kinase C from the cytosolic to the microsomal fraction. Because 1 nM caerulein induced a greater enzyme secretion than 10 pM caerulein during the first 2-5 min of stimulation, we explored further the role of [Ca2+]i transients during the first minutes of secretion. Addition of ionomycin in the presence of 10 pM caerulein resulted in a rise in [Ca2+]i and enhanced secretion as a result of caerulein in a near additive fashion during the first 2 min of stimulation. Second, we pretreated acini for 5 min with 1 microM 12-O-tetradecanoylphorbol-13-acetate. This maneuver inhibited both caerulein-induced inositol trisphosphate formation and [Ca2+]i elevation. These findings were paralleled by a similar inhibition of caerulein-stimulated amylase release only during the first 5 min of secretion. These results indicate that 1) caerulein can stimulate amylase secretion independently of a concomitant [Ca2+]i rise, possibly by activation of protein kinase C, and 2) an elevation of [Ca2+]i serves as a trigger to enhance amylase release only during the initial phase of secretion.
Keywords
Amylases/metabolism Animals Benzofurans Caerulein/*pharmacology Calcium/*metabolism Fura-2 Inositol 1,4,5-Trisphosphate Inositol Phosphates/metabolism Male Pancreas/drug effects/*enzymology Protein Kinase C/*metabolism Rats Rats, Inbred Strains Tetradecanoylphorbol Acetate/pharmacology
Pubmed
Web of science
Create date
24/01/2008 14:30
Last modification date
20/08/2019 15:50
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