Metabolism of acetylcholine in human erythrocytes

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5671105

Chapman, E S

In order to examine the possible role of erythrocyte acetylcholinesterase in the maintenance of membrane phospholipid content and membrane fluidity, experiments were performed to monitor the activity of the enzyme and follow the fate of one of its hydrolytic products, choline. Intact human erythrocytes were incubated with acetylcholine (choline methyl-{sup 14}C). The incubation resulted in the hydrolysis of acetylcholine to acetate and choline; the reaction was catalyzed by membrane acetylcholinesterase. The studies demonstrate the further metabolism of choline. Experiments were carried out to determine rate of hydrolysis of acetylcholine, uptake of choline, identification of intracellular metabolites of choline, and identification of radiolabeled membrane components. Erythrocytes at a 25% hematocrit were incubated in an isoosmotic bicarbonate buffer pH 7.4, containing glucose, adenosine, streptomycin and penicillin with 0.3 {mu}Ci of acetylcholine (choline methyl-{sup 14}C), for 24 hours. Aliquots of the erythrocyte suspension were taken throughout for analysis. Erythrocytes were washed free of excess substrate, lysed, and the hemolysate was extracted for choline and its metabolites. Blank samples containing incubation buffer and radiolabeled acetylcholine only, and erythrocyte hemolysate extracts were analyzed for choline content, the difference between blank samples and hemolysate extracts was the amount of choline originating from acetylcholine and attributable to acetylcholinesterase activity. The conversion of choline to {sup 14}C-betaine is noted after several minutes of incubation; at 30 minutes, more than 80% of {sup 14}C-choline is taken up and after several hours, detectable levels of radiolabeled S-adenosylmethionine were present in the hemolysate extract.

• Research Organization: University of Medicine and Dentistry of New Jersey, Newark, NJ (United States)
• OSTI ID: 5671105
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ACETYLCHOLINE
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOLOGICAL FUNCTIONS
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBOXYLESTERASES
CARBOXYLIC ACID SALTS
CELL CONSTITUENTS
CELL MEMBRANES
CHOLINE
CHOLINESTERASE
DRUGS
ENZYMES
ERYTHROCYTES
ESTERASES
ESTERS
HYDROLASES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPIDS
LIPOTROPIC FACTORS
MAMMALS
MAN
MATERIALS
MEMBRANES
METABOLISM
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PARASYMPATHOMIMETICS
PHOSPHOLIPIDS
PRIMATES
QUATERNARY COMPOUNDS
SYNTHESIS
TRACER TECHNIQUES
VERTEBRATES