Glucose and carbachol activate phospholipase C in digitonin-permeabilized islets

Conference · Fri May 01 00:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5904209

Wolf, B A; Florholmen, J; Turk, J; McDaniel, M L

Stimulation of intact islets with D-glucose, the major insulin secretagogue, or with carbachol, a muscarinic agonist, results in the accumulation of inositoltrisphosphate (IP/sub 3/) suggesting that activation of phospholipase C (PLC) has a major role in stimulus-secretion coupling. Carbachol activation of PLC is an example of receptor-mediated activation in islets, whereas, the mechanism of glucose activation of PLC is controversial since a glucose receptor has not been identified. They have measured PLC activity in digitonin-permeabilized islets. Islets were labeled with /sup 3/H-inositol, permeabilized and IP/sub 3/ accumulation measured by HPLC. Carbachol, in the presence of ATP, GTP and 1 ..mu..M free Ca/sup 2 +/ released two-fold more Ins 1,3,4-P/sub 3/ than control in a time-dependent manner. Glucose, under the same conditions also significantly released more Ins 1,3,4-P/sub 3/ than control. This effect was not due to metabolism of glucose nor to an effect on the IP/sub 3/-phosphomonoesterase. Preliminary Ca/sup 2 +/-dependency studies indicate that PLC is not activated by Ca/sup 2 +/ in the submicromolar range. In conclusion, these studies show that Ca/sup 2 +/ does not activate PLC, and furthermore, that D-glucose may be recognized directly by PLC.

• Research Organization: Washington Univ. School of Medicine, St. Louis, MO
• OSTI ID: 5904209
• Report Number(s): CONF-870644-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 46:6; ISSN FEPRA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
ALKALINE EARTH METAL COMPOUNDS
ATP
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CALCIUM COMPOUNDS
CARBOHYDRATES
CARBOXYLESTERASES
CHROMATOGRAPHY
DRUGS
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
GLUCOSE
HEXOSES
HYDROLASES
INOSITOL
INOSITOLS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPASE
LIPIDS
LIQUID COLUMN CHROMATOGRAPHY
MEMBRANE PROTEINS
MONOSACCHARIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PARASYMPATHOMIMETICS
PERMEABILITY
PHOSPHOLIPIDS
PROTEINS
REACTION KINETICS
RECEPTORS
SACCHARIDES
SEPARATION PROCESSES
SYNTHESIS
TIME DEPENDENCE
TRACER TECHNIQUES
TRITIUM COMPOUNDS