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Title Agonist-sensitive calcium pool in the pancreatic acinar cell. I. Permeability properties
Creator/Author Muallem, S. ; Schoeffield, M.S. ; Fimmel, C.J. ; Pandol, S.J.
Publication Date1988 Aug 01
OSTI IdentifierOSTI ID: 6864650
Other Number(s)CODEN: AJPHA
Resource TypeJournal Article
Resource RelationAm. J. Physiol. ; Vol/Issue: 255
Research OrgCedars-Sinai Medical Center, Los Angeles, CA (USA)
Subject550201 -- Biochemistry-- Tracer Techniques; CALCIUM-- MEMBRANE TRANSPORT;CELL MEMBRANES-- PERMEABILITY; ATROPINE;BIOCHEMICAL REACTION KINETICS;CALCIUM 45;DOSE-RESPONSE RELATIONSHIPS;ETHERS;GUINEA PIGS;IN VITRO;KININS;PANCREAS;PARASYMPATHOMIMETICS;TRACER TECHNIQUES
Related SubjectALKALINE EARTH ISOTOPES;ALKALINE EARTH METALS;ALKALOIDS;ANIMALS;AUTONOMIC NERVOUS SYSTEM AGENTS;BETA DECAY RADIOISOTOPES;BETA-MINUS DECAY RADIOISOTOPES;BODY;CALCIUM ISOTOPES;CELL CONSTITUENTS;DAYS LIVING RADIOISOTOPES;DIGESTIVE SYSTEM;DRUGS;ELEMENTS;ENDOCRINE GLANDS;EVEN-ODD NUCLEI;GLANDS;INTERMEDIATE MASS NUCLEI;ISOTOPE APPLICATIONS;ISOTOPES;KINETICS;MAMMALS;MEMBRANES;METALS;NUCLEI;ORGANIC COMPOUNDS;ORGANIC OXYGEN COMPOUNDS;ORGANS;PARASYMPATHOLYTICS;PEPTIDES;POLYPEPTIDES;PROTEINS;RADIOISOTOPES;REACTION KINETICS;RODENTS;VERTEBRATES
Description/Abstract 45Ca2+ fluxes and free cytosolic Ca2+ (( Ca2+)i) were used to describe the Ca2+ permeability and Ca2+ reloading of the agonist-sensitive pool at rest, during stimulation, and at termination of stimulation.^A sequence of stimulation with carbachol, inhibition with atropine (cycling), and restimulation with cholecystokinin octapeptide (CCK-8) was used to follow Ca2+ reloading.^Reloading of the pool required extracellular Ca2+ and was measured as an increased rate and extent of 45Ca2+ uptake into the acini.^The 45Ca2+ incorporated into cycled acini could be completely released with CCK-8.^The dose-response curves for 45Ca uptake and release were identical to those of the hormonally evoked (Ca2+)i increase.^The increased 45Ca2+ uptake during reloading was not due to an expansion of any intracellular pool size but reflects the labeling of the pool to isotopic equilibrium in cycled acini.^The rate constant of Ca2+ efflux from the pool of resting cells was approximately 0.67 +/- 0.01/h.^With stimulation, the Ca2+ permeability of the pool membrane rapidly increased, resulting in Ca2+ release into the cytosol and an increase in (Ca2+)i.^With termination of stimulation, the Ca2+ permeability of the pool membrane rapidly decreased while the pool continued to reload with extracellular Ca2+.^Labeling of the pool to isotopic equilibrium allowed determination of the amount of Ca2+ released from the pool, which was 2.94 +/- 0.06 nmol/mg protein.^This indicates that total Ca2+ concentration in the pool is in the millimolar range.
Country of PublicationUnited States
LanguageEnglish
FormatPages: G221-G228
System Entry Date2001 May 13

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