Usage Information
Abstract
Recent studies have demonstrated the existence of a novel family of calcium-independent plasmalogen-selective phospholipases A2 in canine myocardium that have been implicated as enzymic mediators of ischemic membrane damage. We now report that human myocardium contains two functionally distinct isoforms of cytosolic calcium-independent phospholipase A2. The major cytosolic phospholipase A2 isoform preferentially hydrolyzes plasmalogen substrate, possesses a pH optimum of 7.0, and is chromatographically resolvable from a minor cytosolic calcium-independent phospholipase A2 isoform that hydrolyzes plasmenylcholine and phosphatidylcholine substrates at similar rates and possesses a pH optimum of 8.5. The major cytosolic calcium-independent phospholipase A2 isoform was identified as a 40-kD polypeptide after its 182,000-fold purification by sequential column chromatographies to a final specific activity of 67 mumol/mg.min. The purified 40-kD human myocardial phospholipase A2 preferentially hydrolyzes plasmalogens containing arachidonic acid at the sn-2 position. Both reverse-phase HPLC and fast atom bombardment mass spectroscopic analysis of human myocardial ethanolamine and choline glycerophospholipids demonstrated that plasmenylethanolamine and plasmenylcholine molecular species containing arachidonic acid at the sn-2 position are prominent constituents of human myocardium. Collectively, these results identify and characterize the major human myocardial cytosolic calcium-independent phospholipase A2 activity, demonstrate the presence of functionally distinct human myocardial cytosolic calcium-independent phospholipase A2 isoforms, and document the abundance of arachidonoylated plasmalogen molecular species in human myocardium that serve as substrates.
Authors
S L Hazen, C R Hall, D A Ford, R W Gross
Usage data is cumulative from September 2025 through September 2026.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 332 | 21 |
| 173 | 13 | |
| Figure | 0 | 3 |
| Scanned page | 950 | 3 |
| Citation downloads | 207 | 0 |
| Totals | 1,662 | 40 |
| Total Views | 1,702 | |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)