Open AccessCirculating Microparticles Carry a Functional Endothelial Nitric Oxide Synthase That Is Decreased in Patients With Endothelial Dysfunction
Author(s) -
Horn Patrick,
CorteseKrott Miriam Margherita,
Amabile Nicolas,
Hundsdörfer Claas,
Kröncke KlausDietrich,
Kelm Malte,
Heiss Christian
Publication year - 2013
Publication title -
journal of the american heart association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.494
H-Index - 85
ISSN - 2047-9980
DOI - 10.1161/jaha.112.003764
Subject(s) - enos , nitric oxide synthase type iii , western blot , nitric oxide synthase , endothelial dysfunction , nitric oxide , medicine , enzyme , endothelium , citrulline , endothelial stem cell , endothelial nitric oxide synthase , endothelial nos , platelet , biochemistry , arginine , biology , in vitro , gene , amino acid
Background Microparticles ( MP s) are circulating membrane particles of less than a micrometer in diameter shed from endothelial and blood cells. Recent literature suggests that MP s are not just functionally inert cell debris but may possess biological functions and mediate the communication between vascular cells. As a significant proportion of MP s originate from platelets and endothelial cells, we hypothesized that MP s may harbor functional enzymes including an endothelial NO synthase ( eNOS ). Methods and Results Using immunoprecipitation and W estern blot analysis, we found that human circulating MP s carry an eNOS . Ca 2+ and l ‐arginine‐dependent NOS activity of crude enzyme extract from MP s was determined by measuring the conversion of [ 3 H]‐L‐arginine to [ 3 H]‐citrulline and NOS ‐dependent nitrite production. NOS ‐dependent NO production in intact MP s was assessed by the NO ‐specific fluorescent probe MNIP ‐Cu. In patients with cardiovascular disease, endothelial dysfunction was associated with an increase in the total number of circulating MP s as well as a significant decrease in the expression and activity of eNOS in MP s. No difference in reactive oxygen species was noted in MP s isolated from either group. Conclusions Our data further support the concept that circulating MP s may not only retain phenotypic markers but also preserve the functionality of enzymes of the cells they originate from, including eNOS .