title: Subthreshold High-Frequency Electrical Field Stimulation Induces VEGF Expression in Cardiomyocytes.
abstract: Subthreshold electrical stimulation (SES) has been shown to induce an improvement of angiogenesis in ischemic and nonischemic skeletal muscles, mediated by increased VEGF expression. VEGF plays a key role in physiological and pathological angiogenesis. Cardiomyocytes possess the ability to synthesize and secrete VEGF. Thus, we thought to investigate the effect of SES on VEGF regulation in cultured neonatal rat ventricular myocytes (NRVMs), in the aim to reveal new techniques for therapeutic angiogenesis in ischemic heart disease. Cell cultures of NRVMs were electrically stimulated with field strengths below the myocyte depolarization threshold (0.5 V/cm with 1 ms bipolar impulse duration). Frequencies ranging from 5 Hz up to 25, 50, and 99 Hz were applied over a period of 48 h. The expression of VEGF and its receptor KDR was determined with Western blot and ELISA. To reveal the biological activity of the secreted VEGF amount, cultured human coronary artery endothelial cells (HCAECs) were treated with the cell culture supernatant of NRVMs exposed to SES. A dominant effect of SES was observed at 25 Hz. Within this particular frequency the VEGF protein amount in the cytoplasm as well as in the cell culture supernatant increased significantly. In parallel, the protein expression of the KDR receptor decreased in a significant manner. Moreover, cell culture supernatant of NRVMs exposed to SES augmented the growth of HCAECs. Cardiomyocytes respond to SES with an increase in biologically active VEGF expression that promotes cell proliferation of HCAECs. This mechanism may provide new approaches to develop therapeutic angiogenesis in the ischemic heart.
authors.affiliation: Department of Cardiology, University Hospital, Aachen, Germany.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Rackauskas
authors.forename: Erol
authors.initials: E
authors.lastname: Saygili
authors.forename: Obaida R
authors.initials: OR
authors.lastname: Rana
authors.forename: Esra
authors.initials: E
authors.lastname: Saygili
authors.forename: Christopher
authors.initials: C
authors.lastname: Gemein
authors.forename: Aleksandras
authors.initials: A
authors.lastname: Laucevicius
authors.forename: Audrius
authors.initials: A
authors.lastname: Aidietis
authors.forename: Germanas
authors.initials: G
authors.lastname: Marinskis
authors.forename: Pranas
authors.initials: P
authors.lastname: Serpytis
authors.forename: Jurgita
authors.initials: J
authors.lastname: Plisiene
authors.forename: Dainius H
authors.initials: DH
authors.lastname: Pauza
authors.forename: Patrick
authors.initials: P
authors.lastname: Schauerte
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004558:Electric Stimulation; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2