Nutrient and hormone-neurotransmitter stimuli induce hydrolysis of polyphosphoinositides in rat pancreatic islets
Preincubation of rat pancreatic islets with /sup 3/H-inositol, and subsequent exposure, in the presence of LiCl, to either glucose or carbamylcholine resulted in a rapid stimulation of /sup 3/H-inositol 1,4,5-triphosphate and /sup 3/H-myo-inositol 1,4-bisphosphate formation, the level of which reached a plateau after about 5 min of stimulation. Both stimuli also caused an approximately linear accumulation of /sup 3/H-myo-inositol 1-phosphate. The amounts of /sup 3/H-inositol phosphates formed were dependent on the concentration of LiCl. Studies of /sup 32/P-labeling of islet ATP, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), and phosphatidylinositol 4-phosphate revealed that these approached isotopic equilibrium after about 240-min incubation, whereas /sup 32/P-labeling of phosphatidylinositol, phosphatidic acid, phosphatidylcholine, and phosphatidylethanolamine proceeded at a lower rate. Carbamylcholine provoked an immediate fall in /sup 32/P-PtdIns(4,5)P2 and, to a lesser extent, /sup 32/P-phosphatidylinositol 4-phosphate. Glucose caused a similar response although, in this case, the most marked decline was in a more polar /sup 32/P-labeled lipid. Cholecystokinin-pancreozymin was also found to induce /sup 32/P-PtdIns(4,5)P2 hydrolysis, although the ionophore A23187 was without effect. Both carbamylcholine and glucose induced an increase in /sup 32/P-phosphatidic acid. The results provide two independent pieces of evidence suggesting that phospholipase C-mediated hydrolysis of polyphosphoinositides occurs as an early response in rat islets to either nutrient or neurotransmitter secretagogues.
- Research Organization:
- Brussels Free Univ., Belgium
- OSTI ID:
- 6006012
- Journal Information:
- Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 115:5; ISSN ENDOA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALDEHYDES
ALKALI METAL COMPOUNDS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
ATP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BODY
CARBOHYDRATES
CARBOXYLESTERASES
CHEMICAL REACTIONS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CHOLINE
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DIGESTIVE SYSTEM
DRUGS
ENDOCRINE GLANDS
ENZYMES
ESTERASES
GLANDS
GLUCOSE
HALIDES
HALOGEN COMPOUNDS
HEXOSES
HYDROGEN ISOTOPES
HYDROLASES
HYDROLYSIS
HYDROXY COMPOUNDS
INOSITOL
INOSITOLS
ISOTOPE APPLICATIONS
ISOTOPES
KININS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPASE
LIPOTROPIC FACTORS
LITHIUM CHLORIDES
LITHIUM COMPOUNDS
LITHIUM HALIDES
LYSIS
MAMMALS
MONOSACCHARIDES
NUCLEI
NUCLEOTIDES
NUTRIENTS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PANCREAS
PEPTIDES
PHOSPHATES
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
POLYPEPTIDES
PROTEINS
QUATERNARY COMPOUNDS
RADIOISOTOPES
RATS
RESPONSE MODIFYING FACTORS
RODENTS
SACCHARIDES
SOLVOLYSIS
TRACER TECHNIQUES
TRITIUM
VERTEBRATES
YEARS LIVING RADIOISOTOPES