Abstract TP262: Pulsed Electromagnetic Field (PEMF) Increases Microvascular Flow And Tissue Oxygenation In the Normal Rat Brain

Abstract

Introduction: Pulsed Electromagnetic Field (PEMF) treatment has been shown to improve wound healing through increased nitric oxide levels. Thus, we hypothesized that PEMF improves microvascular (MV) flow and tissue oxygenation in the brain. Methods: Using in-vivo 2-photon laser scanning microscopy (2PLSM) over the parietal cortex of the normal rat brain, we measured MV red blood cell (RBC) flow velocity, diameters (range 3 to 15 μm which includes arterioles and venules), and tissue oxygenation (NADH fluorescence) before, during 30 minutes PEMF treatment and for three hours thereafter (three sessions with 30 min intervals). Doppler flux (0.9 mm probe diameter), arterial blood pressure, intracranial pressure, and arterial blood gases were concurrently monitored. Results: Microvascular flow velocities and diameters increased after PEMF treatment. Average MV diameters (300 MV measured in each of six rats) increased from 9.1±1.8 μm before to 9.4±2.1 μm during PEMF treatment (n=6, p<0.05). Blood flow velocities also increased by 4.4±1.3 and 2.3±1.1 % during and after PEMF treatment respectively in comparison to baseline (p<0.05). PEMF treatment decreased NADH autofluorescence indicating better tissue oxygenation and increased blood supply (96.1±2.4 and 98.2±1.3 % during and after PEMF treatment, respectively, compared to the baseline, p<0.05). Laser Doppler flux averaged over a brain volume of 1 mm3 was unchanged before and during PEMF treatment. Conclusions: Thirty minutes of PEMF treatment induced MV dilation, increased RBC velocity and tissue oxygenation that persisted for 3 hours. Within the 3-hour period, however, MV diameters and RBC velocities gradually returned to baseline. Whether the effects observed are nitric oxide induced remains to be determined.