Phorbol 12,13-dibutyrate and 1-oleyl-2-acetyldiacylglycerol stimulate inositol trisphosphate dephosphorylation in human platelets.
Inositol trisphosphate (IP3) is formed in response to specific agonists that cause activation of phospholipase C and degradation of phosphatidylinositol bisphosphate. IP3 is a second messenger that releases Ca2+ from the dense tubular system to the cytosol in stimulated platelets. Our present information indicates that [3H]IP3 is dephosphorylated to [3H]inositol bisphosphate (IP2) and [3H]inositol monophosphate (IP) by human platelets treated with 0.05-0.10% Triton X-100. This dephosphorylation of [3H]IP3 to [3H]IP2 and [3H]IP is also observed when platelets are permeabilized by electrical stimulation or by 20 micrograms/ml saponin. These detergents or electropermeabilization allow IP3 to access cytosolic IP3 phosphatase. Pretreatment of intact platelets with phorbol dibutyrate and 1-oleyl-2-acetyldiacylglycerol for 30 s, at concentrations that maximally activate protein kinase C, stimulates the conversion of IP3 to IP2 and IP. This suggests a role for protein kinase C in the regulation of IP3 degradation.
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology*; D005989:Glycerides / Q000494:pharmacology*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000097:blood*; D007700:Kinetics; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology*; D010766:Phosphorylation; D013403:Sugar Phosphates / Q000097:blood*; D014316:Tritium
D004075:Diglycerides; D005989:Glycerides; D007295:Inositol Phosphates; D010703:Phorbol Esters; D013403:Sugar Phosphates; D014316:Tritium; D015240:Phorbol 12,13-Dibutyrate; D015544:Inositol 1,4,5-Trisphosphate; C038237:1-oleoyl-2-acetylglycerol