Agonist-sensitive calcium pool in the pancreatic acinar cell. II. Characterization of reloading

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · Am. J. Physiol.; (United States)

OSTI ID:6769273

Muallem, S; Schoeffield, M S; Fimmel, C J; Pandol, S J

45Ca2+ fluxes and free cytosolic Ca2+ measurements in guinea pig pancreatic acini indicated that after agonist stimulation and the release of Ca2+ from the agonist-sensitive pool at least part of the Ca2+ is extruded from the cell, resulting in 45Ca2+ efflux. In the continued presence of agonist, the pool remains permeable to Ca2+ but partially refills with Ca2+. This reloading is dependent on the concentration of extracellular Ca2+. In the absence of extracellular Ca2+, the pool is completely depleted of Ca2+. However, with increasing concentrations of CaCl2 in the incubation solution (from 0.5 to 2.0 mM) there is increasing repletion of the pool with Ca2+ during agonist stimulation. With termination of agonist stimulation, the Ca2+ permeability of the agonist-sensitive pool is rapidly reduced to that measured in the unstimulated cell. As a result, the Ca2+ incorporated into the pool during the stimulation period is rapidly trapped within the pool and exchanges poorly with medium Ca2+. Subsequently, the pool completely refills with Ca2+. The rate of Ca2+ reloading at the termination of agonist stimulation is slower than the conversion of the pool to the impermeable state. In incubation media containing 1.3 mM CaCl2, the half-time for reloading at the termination of stimulation is 5 min. These observations demonstrate the characteristics of Ca2+ reloading of the agonist-sensitive pool both during stimulation and at the termination of stimulation.

• Research Organization: Cedars-Sinai Medical Center, Los Angeles, CA (USA)
• OSTI ID: 6769273
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 255; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ALKALOIDS
ANIMALS
ATROPINE
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHELATING AGENTS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DRUGS
EGTA
ELEMENTS
ENDOCRINE GLANDS
ETHERS
EVEN-ODD NUCLEI
GLANDS
GLYCOLS
GUINEA PIGS
HYDROXY COMPOUNDS
IN VITRO
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
METALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
PANCREAS
PARASYMPATHOLYTICS
PERMEABILITY
RADIOISOTOPES
RODENTS
TRACER TECHNIQUES
VERTEBRATES