Membrane depolarization and carbamoylcholine stimulate phosphatidylinositol turnover in intact nerve terminals

Journal Article · Fri Apr 01 04:00:00 EST 1988 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.85.8.2859· OSTI ID:6208293

Audigier, S M.P.; Wang, J K.T.; Greengard, P

Synaptosomes, purified from rat cerebral cortex, were prelabeled with (/sup 3/H)inositol to study phosphatidylinositol turnover in nerve terminals. Labeled synaptosomes were either depolarized with 40 mM K/sup +/ or exposed to carbamoylcholine (carbachol). K/sup +/ depolarization increased the level of inositol phosphates in a time-dependent manner. The inositol bisphosphate level also increased rapidly, but its elevated level was sustained during continued depolarization. The elevated level of inositol bisphosphate was reversed upon repolarization of the synaptosomes. The level of inositol monophosphate increased slowly to 120-130% of control. These effects of K/sup +/ depolarization depended on the presence of Ca/sup 2 +/ in the incubation medium. Carbachol stimulated the turnover of phosphatidylinositol in a dose- and time-dependent manner. The level of inositol bisphosphate increased to 210% of control, and this maximal response was seen from 15 to 60 min. Accumulation of inositol monophosphate was larger than that of inositol bisphosphate, but its time course was slower. Atropine and pirenzepine inhibited the carbachol effect with high affinities. These data show that both Ca/sup 2 +/ influx and M/sub 1/ muscarinic receptor activation stimulate phospholipase C activity in synaptosomes, suggesting that phosphatidylinositol turnover may be involved in regulating neurotransmitter release from nerve terminals.

• Research Organization: Rockefeller Univ., New York, NY (USA)
• OSTI ID: 6208293
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 85:8; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALKALI METAL COMPOUNDS
ALKALOIDS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
ATROPINE
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
CHOLINE
DAYS LIVING RADIOISOTOPES
DEPOLARIZATION
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ENZYMES
HYDROXY COMPOUNDS
INOSITOLS
IONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
METABOLISM
MONOSACCHARIDES
NERVES
NERVOUS SYSTEM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PARASYMPATHOLYTICS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
POTASSIUM COMPOUNDS
PROTEINS
QUATERNARY COMPOUNDS
RADIOISOTOPES
RATS
RECEPTORS
RODENTS
SACCHARIDES
TIME DEPENDENCE
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES