Ca/sup 2 +/-stimulated catecholamine release from. cap alpha. -toxin-permeabilized PC12 cells: biochemical evidence for exocytosis and its modulation by protein kinase C and G protein

Journal Article · Tue Dec 01 00:00:00 EST 1987 · Biochemistry; (United States)

OSTI ID:5356017

Ahnert-Hilger, G; Braeutigam, M; Gratzl, M

Two possible cellular pathways of catecholamines from the chromaffin vesicles of PC12 cells to the surrounding medium are explored in this study. The direct one circumventing the cytoplasm can be activated in ..cap alpha..-toxin-permeabilized cells with micromolar levels of free Ca/sup 2 +/. Catecholamine metabolites formed in the cytoplasm (i.e., 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxyphenylethanol) are neither formed nor released from the cells under these conditions. However, when vesicular catecholamines were discharged into the cytoplasm by addition of the ionophore nigericin, such metabolites are formed and released into the medium independent of Ca/sup 2 +/. Both types of experiments provide direct evidence for the operation of Ca/sup 2 +/-induced exocytosis of dopamine and noradrenaline in permeabilized PC12 cells. The Ca/sup 2 +/ dependence of dopamine or noradrenaline release, as measured by the determination of the endogenous catecholamines using the high-performance liquid chromatography technique, exhibits two different phases. One is already activated below ..mu..M free Ca/sup 2 +/ and plateaus at 1-5 ..mu..M free Ca/sup 2 +/, while a second occurs in the presence of larger amounts of free Ca/sup 2 +/ (10-100 ..mu..M). Ca/sup 2 +/-induced catecholamine release from the permeabilized cells can be modulated in different ways: It is enhanced by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate and the diacylglycerol 1-oleyl-2-acetylglycerol provided Mg/sup 2 +//ATP is present, and it is inhibited by guanosine 5'-O-(3-thiotriphosphate). The latter effect is abolished by pretreatment of the cells with pertussis toxin but not by cholera toxin. Thus, it appears that Ca/sup 2 +/-induced exocytosis can be modulated via the protein kinase C system, as well as via GTP binding proteins.

• Research Organization: Universitaet Ulm, West Germany
• OSTI ID: 5356017
• Journal Information: Biochemistry; (United States), Vol. 26:24
• 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.
CATECHOLAMINES
PHAGOCYTOSIS
SECRETION
PHORBOL ESTERS
BIOLOGICAL EFFECTS
TRITIUM COMPOUNDS
CALCIUM COMPOUNDS
DOPAMINE
MAGNESIUM COMPOUNDS
METABOLITES
PERMEABILITY
PHOSPHOTRANSFERASES
PROTEINS
RATS
TOXINS
TUMOR CELLS
ALKALINE EARTH METAL COMPOUNDS
AMINES
ANIMAL CELLS
ANIMALS
ANTIGENS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARCINOGENS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DRUGS
ENZYMES
ESTERS
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
NEUROREGULATORS
ORGANIC COMPOUNDS
PHENOLS
PHOSPHORUS-GROUP TRANSFERASES
POLYPHENOLS
RODENTS
SYMPATHOMIMETICS
TOXIC MATERIALS
TRANSFERASES
VERTEBRATES
550301* - Cytology- Tracer Techniques
560300 - Chemicals Metabolism & Toxicology