Modulation of cytosolic free calcium levels by extracellular phosphate and lanthanum

Journal Article · Sun Mar 01 00:00:00 EST 1987 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.84.5.1282· OSTI ID:6372501

Korc, M; Schoeni, M H

The effects of extracellular phosphate and lanthanum on cytosolic free Ca/sup 2 +/ ((Ca/sup 2 +/)/sub i/) levels were studied in isolated rat pancreatic acini. In the presence of 1.28 mM Ca/sup 2 +/ and 1.0 mM phosphate, the mean resting (Ca/sup 2 +/)/sub i/ level was 120 nM. Omission of phosphate from incubation medium significantly lowered this value to 94 nM. The gastrointestinal hormone cholecystokinin octapeptide (CCK-8) rapidly enhanced both (Ca/sup 2 +/)/sub i/ levels and /sup 45/Ca/sup 2 +/ efflux, irrespective of the presence or absence of phosphate. Lanthanum (0.1 mM), a compound known to block transmembrane Ca/sup 2 +/ fluxes, attenuated both actions of CCK-8, but only in the absence of extracellular phosphate. There was a concomitant decrease in amylase secretion induced by 0.1 nM CCK-8 but not by 10 nM CCK-8, without a significant change in cellular ATP levels. The inhibitory actions of lanthanum on CCK-8-stimulated (Ca/sup 2 +/)/sub i/ levels were very rapid and were mimicked only by prolonged incubation of acini in Ca/sup 2 +/-free medium supplemented with EGTA. Omission of phosphate from incubation medium also lowered basal (Ca/sup 2 +/)/sub i/ levels in IM-9 lymphocytes. These findings suggest that extracellular phosphate may modulate resting (Ca/sup 2 +/)/sub i/ levels in pancreatic acini and other cell types and that mobilization of intracellular Ca/sup 2 +/ may partly depend on the availability of a lanthanum-sensitive pool of cell-surface Ca/sup 2 +/ that is not readily removed by EGTA.

• Research Organization: Univ. of Arizona, Tucson, AZ (United States)
• OSTI ID: 6372501
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:5
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CALCIUM 45
MEMBRANE TRANSPORT
LANTHANUM
BIOCHEMISTRY
SODIUM PHOSPHATES
AMYLASE
CALCIUM COMPOUNDS
CATIONS
LYMPHOCYTES
METABOLIC DISEASES
PANCREAS
RATS
SODIUM CHLORIDES
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CALCIUM ISOTOPES
CHARGED PARTICLES
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DISEASES
ELEMENTS
ENDOCRINE GLANDS
ENZYMES
EVEN-ODD NUCLEI
GLANDS
GLYCOSYL HYDROLASES
HALIDES
HALOGEN COMPOUNDS
HYDROLASES
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPES
LEUKOCYTES
MAMMALS
MATERIALS
METALS
NUCLEI
O-GLYCOSYL HYDROLASES
ORGANS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
RADIOISOTOPES
RARE EARTHS
RODENTS
SODIUM COMPOUNDS
SOMATIC CELLS
VERTEBRATES
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