Multiple sources of 1,2-diacylglycerol in isolated rat pancreatic acini stimulated by cholecystokinin. Involvement of phosphatidylinositol bisphosphate and phosphatidylcholine hydrolysis

Journal Article · Tue Sep 05 04:00:00 EDT 1989 · Journal of Biological Chemistry; (USA)

OSTI ID:5345830

Matozaki, T; Williams, J A ^[1]

---

1. Univ. of Michigan, Ann Arbor (USA)

Changes in the cellular content of 1,2-diacylglycerol (DAG) in isolated rat pancreatic acini in response to agonist stimulation were studied using a sensitive mass assay. When acini were stimulated by 10 nM COOH-terminal cholecystokinin-octapeptide (CCK8), the increase in DAG was biphasic, consisting of an early peak at 5 s and a second, larger, gradual increase that was maximal by 15 min. The basal level of DAG in acini was 1.04 nmol/mg of protein, which was increased to 1.24 nmol/mg of protein at 5 s and 2.76 nmol/mg of protein at 30 min. In comparison, the increase in DAG stimulated by 30 pM CCK8, a submaximal concentration for amylase release, was monophasic, increasing without an early peak but sustained to 60 min. Other Ca2+-mobilizing secretagogues such as carbamylcholine and bombesin increased DAG in acini, whereas vasoactive intestinal peptide, which acts to increase cAMP, had no effect. Phorbol ester and Ca2+ ionophore also stimulated DAG production. Analysis of the mass level of inositol 1,4,5-trisphosphate (1,4,5-IP3) showed that the generation of 1,4,5-IP3 stimulated by 10 nM CCK8 peaked at 5 s, a finding consistent with the early peak of DAG. The basal level was 4.7 pmol/mg of protein, which was increased to 144.6 pmol/mg of protein at 5 s by 10 nM CCK8. The levels of 1,4,5-IP3 then returned toward basal in contrast to the gradual and sustained increase of DAG. The dose dependencies of 1,4,5-IP3 and DAG formation at 5 s with respect to CCK8 were almost identical. This suggests that phosphatidylinositol 4,5-bisphosphate hydrolysis is a major source of the early increase in DAG but not of the sustained increase in DAG. Therefore, a possible contribution of phosphatidylcholine hydrolysis to DAG formation was examined utilizing acini prelabeled with (3H)choline. CCK8 (1 nM) maximally increased (3H)choline metabolite release by 133% of control at 30 min.

• OSTI ID: 5345830
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 264:25; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOSYNTHESIS
BODY
CARCINOGENS
CHEMICAL REACTIONS
CHOLINE
DECOMPOSITION
DIGESTIVE SYSTEM
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ENDOCRINE GLANDS
ESTERS
GLANDS
GLYCEROL
HYDROGEN COMPOUNDS
HYDROLYSIS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
KININS
LIPIDS
LIPOTROPIC FACTORS
LYSIS
MAMMALS
METABOLISM
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PANCREAS
PEPTIDES
PHORBOL ESTERS
PHOSPHOLIPIDS
POLYPEPTIDES
PROTEINS
QUATERNARY COMPOUNDS
RATS
REACTION KINETICS
RODENTS
SOLVOLYSIS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES