In Situ Electrostimulation Drives a Regenerative Shift in the Zone of Infarcted Myocardium

Subthreshold High-Frequency Electrical Field Stimulation Induces VEGF Expression in Cardiomyocytes

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.

Effects of electroacupuncture on recovery of the electrophysiological properties of the rabbit gastrocnemius after contusion: an in vivo animal study

Background

Our preliminary studies indicated that electroacupuncture (EA) at the ST36 and Ashi acupoints could promote regeneration of the rabbit gastrocnemius (GM) by improving microcirculation perfusion, promoting the recovery of myofiber structures, and inhibiting excessive fibrosis. However, the effects of EA on recovery of the electrophysiological properties of the GM after contusion are not yet clear. Thus, the purpose of this study was to investigate the effects of EA at the Zusanli (ST36) and Ashi acupoints with regard to recovery of the electrophysiological properties of the rabbit GM after contusion.

Methods

Forty-five rabbits were randomly divided into three groups: normal, contusion, and EA. After an acute GM contusion was produced (in rabbits in the contusion and EA groups), rabbits in the EA group were treated with electrostimulation at the ST36 and Ashi acupoints with 0.4 mA (2 Hz) for 15 min. The contusion group received no EA treatment. At different time points (7, 14, and 28 days) after contusion, we performed surface electromyography (EMG) and measured the nerve conduction velocity (NCV) of the GM and the GM branch of the tibial nerve. We also examined acetylcholinesterase (AchE) and Agrin expression in the neuromuscular junction (NMJ) via immunohistochemistry.

Results

Compared with the contusion group, the EMG amplitude and NCV in rabbits in the EA group were significantly higher at all time points after contusion. AchE and Agrin expression in the EA group were significantly higher than those in the contusion group.

Conclusions

Our results showed that EA at the ST36 and Ashi acupoints effectively promoted recovery of the electrophysiological properties of the rabbit GM after contusion. The effects of EA were realized by promotion of the regeneration of myofibers and nerve fibers, as well as acceleration of NMJ reconstruction by upregulation of AchE and Agrin expression in the motor endplate area.