G protein in stimulation of PI hydrolysis by CCK (cholecystokinin) in isolated rat pancreatic acinar cells
- Kobe Univ. School of Medicine (Japan)
To clarify the possible role of a guanine nucleotide-binding protein (G protein) in the signal transducing system activated by cholecystokinin (CCK), actions of CCK on rat pancreatic acini were compared with those of fluoride, a well-known activator of stimulatory (G{sub s}) or inhibitory (G{sub i}) G protein. When acini were incubated with increasing concentrations of either CCK-octapeptide (CCK8) or NaF, a maximal stimulation of amylase release from acini occurred at 100 pM CCK8 or 10 mM NaF, respectively; this secretory rate decreased as CCK8 or NaF concentration was increased. NaF caused an increase in cytoplasmic Ca{sup 2+} concentration from the internal Ca{sup 2+} store and stimulated accumulation of inositol phosphates in acini, as observed with CCK. Guanylimidodiphosphate activated the generation of inositol phosphates in the ({sup 3}H)inositol-labeled pancreatic acinar cell membrane preparation, with half-maximal and maximal stimulation at 1 and 10 {mu}M, respectively. Furthermore, the effects of submaximal CCK concentrations on inositol phosphate accumulation in membranes were markedly potentiated in the presence of 100 {mu}M GTP, which alone was ineffective. Combined findings of the present study strongly suggest that pancreatic CCK receptors are probably coupled to the activation of polyphosphoinositide (PI) breakdown by a G protein, which appears to be fluoride sensitive but is other than G{sub s}- or G{sub i}-like protein.
- OSTI ID:
- 6230081
- Journal Information:
- American Journal of Physiology; (USA), Vol. 255:5; ISSN 0002-9513
- Country of Publication:
- United States
- Language:
- English
Similar Records
Multiple sources of 1,2-diacylglycerol in isolated rat pancreatic acini stimulated by cholecystokinin. Involvement of phosphatidylinositol bisphosphate and phosphatidylcholine hydrolysis
Preparation and characterization of a probe for the cholecystokinin octapeptide receptor, N/sup. cap alpha. / (/sup 125/I-desaminotyrosyl)CCK-8, and its interactions with pancreatic acini
Related Subjects
INOSITOLS
HYDROLYSIS
KININS
BIOLOGICAL EFFECTS
PROTEINS
RECEPTORS
AMYLASE
PANCREAS
RATS
SODIUM FLUORIDES
TRITIUM COMPOUNDS
ALKALI METAL COMPOUNDS
ANIMALS
BODY
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
DIGESTIVE SYSTEM
ENDOCRINE GLANDS
ENZYMES
FLUORIDES
FLUORINE COMPOUNDS
GLANDS
GLYCOSYL HYDROLASES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROLASES
LYSIS
MAMMALS
MEMBRANE PROTEINS
MONOSACCHARIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
POLYPEPTIDES
RODENTS
SACCHARIDES
SODIUM COMPOUNDS
SOLVOLYSIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques