Abstract 12699: Microparticles from Endothelial Cells Serve as Circulating NO Donor
Introduction: Eukaryotic cells release fine vesicles called microparticles (MPs) from plasma membrane. Endothelial cells (ECs) also release MPs into the blood, but the physiological significance is unclear. Here we show that eNOS in the MPs released from ECs still sustained its functional activity as in ECs.
Methods and Results: Cultured bovine aortic ECs were washed and exchanged with serum free medium, then incubated for 15 min. The medium was collected and cell debris was removed. Expression of eNOS was confirmed in MPs obtained from the medium by western blotting. The cell-debris-free conditioned medium was divided to several portions and added ATP or ionomycin or/and NOS inhibitor L-NAME, or centrifuged to remove MPs. To these media NO fluorescent indicator DAF2 was applied to measure NO concentration and it was found that NO was significantly increased in response to either ATP or ionomycin (1.20 ± 0.06 and 1.29 ± 0.12 times that of control, respectively) in the medium. This NO production was sensitive to L-NAME treatment and MPs elimination. Production of cGMP in rat smooth muscle cells (SMCs) by applying ECs’ conditioned medium was examined in presence or absence of MPs. The cGMP production in SMCs was almost double when conditioned medium contains MPs.
Conclusions: ECs release MPs which contain eNOS and produce NO in the circulating fluid to cause vasodilatation. Our results suggest that MPs from ECs would function as NO donor in circulatory dynamics.
- © 2013 by American Heart Association, Inc.