Related Experiment Video

Updated: Sep 29, 2026

Primary Culture of Adult Rat Heart Myocytes
11:44

Primary Culture of Adult Rat Heart Myocytes

Published on: June 15, 2009

Stimulation of different phospholipase A2 isoforms by TNF-alpha and IL-1beta in adult rat ventricular myocytes

S J Liu1, J McHowat

  • 1Department of Biopharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.

The American Journal of Physiology
|September 24, 1998
PubMed

We previously showed that in adult rat ventricular myocytes interleukin (IL)-1beta activates a membrane-associated, Ca2+-independent phospholipase A2 (iPLA2). In this study, we examined the possible existence of different PLA2 isoforms and effects of tumor necrosis factor (TNF)-alpha on iPLA2 activities. Western blot analysis identified iPLA2 in both membrane (approximately 82 kDa) and cytosolic (approximately 40 kDa) fractions and identified Ca2+-dependent PLA2 (cPLA2) only in cytosolic fractions. With plasmenylcholine or alkylacyl glycerophosphorylcholine as substrate, TNF-alpha elicited a twofold transient increase in cytosolic iPLA2 activity accompanied by an increase in arachidonic acid release and decreased membrane-associated iPLA2 activity with plasmenylcholine. With phosphatidylcholine as substrate, TNF-alpha decreased both cytosolic and membrane-associated iPLA2 activities. TNF-alpha-induced increases in cytosolic iPLA2 activity and arachidonic acid release were completely blocked by methyl arachidonyl fluorophosphonate (MAFP) but not by bromoenol lactone (BEL). TNF-alpha and IL-1beta together enhanced synergistically cytosolic and membrane PLA2 activities and arachidonic acid release that were blocked differentially by MAFP and BEL, respectively, and inhibited completely by MAFP plus BEL. These results suggest that TNF-alpha and IL-1beta act on different PLA2 isoforms in ventricular myocytes.

More Related Videos

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS07:33

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS

Published on: December 21, 2011

Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes07:32

Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes

Published on: May 25, 2022

Related Concept Videos

Amplifying Signals via Second Messengers01:15

Amplifying Signals via Second Messengers

Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
IP3/DAG Signaling Pathway01:11

IP3/DAG Signaling Pathway

Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the  phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...