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Thrombin and PAF stimulate formation of inositol triphosphate from similar pools of phosphatidylinositol-4,5-bisphosphate in platelets

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:7108712
;

During platelet activation phospholipase C cleaves phosphatidylinositol-4,5-bisphosphate (PIP/sub 2/) to generate diacylglycerol and inositol triphosphate (IP/sub 3/). Production of IP/sub 3/ was therefore used as a probe to differentiate between thrombin and platelet activating factor (PAF) sensitive pools of PIP/sub 2/. Stimulation of (/sup 3/H)inositol labelled rabbit platelets (0.5 x 10/sub 9/ cells/ml containing 0.1 mM EGTA and 2 mM LiCl) with thrombin (1 U/ml) caused a maximum 3 to 10 fold increase in (/sup 3/H)IP/sup 3/ in 5 min. Treatment with PAF (1 x 10/sup -9/ M) led to a maximum 3 to 5 fold increase in (/sup 3/H)IP/sub 3/ in 5 s followed by a decrease to basal level in 30 s. Addition of thrombin for 5 min followed by PAF for 5 s showed no further increase in (/sup 3/H)IP/sub 3/ over that obtained with thrombin alone. Various other sequential treatments with thrombin and PAF showed negligible cumulative effect. Simultaneous addition of thrombin and PAF showed a partial additive production of (/sup 3/H)IP/sub 3/ at short time periods but these levels never significantly exceeded those obtained by thrombin at 5 min or PAF at 5 s. It is concluded that in platelets thrombin and PAF (a) differentially activate PIP/sub 2/-phosphodiesterase and (b) stimulate production of IP/sub 3/ from similar pools of PIP/sub 2/.

Research Organization:
UMHSC, Columbia, MO
OSTI ID:
7108712
Report Number(s):
CONF-8606151-
Journal Information:
Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CARBOHYDRATES
CARBOXYLESTERASES
COAGULANTS
DRUGS
ENZYMES
ESTERASES
ESTERS
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROLASES
INOSITOL
INOSITOLS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPASE
LIPIDS
MATERIALS
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHATES
PHOSPHOLIPIDS
PHOSPHORUS COMPOUNDS
REACTION KINETICS
SACCHARIDES
SERINE PROTEINASES
THROMBIN
TRACER TECHNIQUES
TRITIUM COMPOUNDS