Abstract
Blood flowing in microvessels is one possible site of action of static magnetic fields (SMFs). We evaluated SMF effects on capillary flow of red blood cells (RBCs) in unanesthetized hamsters, using a skinfold chamber technique for intravital fluorescence microscopy. By this approach, capillary RBC velocities (vRBC), capillary diameters (D), arteriolar diameters (Dart), and functional vessel densities (FVD) were measured in striated skin muscle at different magnetic flux densities. Exposure above a threshold level of about 500 mT resulted in a significant (P < 0.001) reduction of vRBC in capillaries as compared to the baseline value. At the maximum field strength of 587 mT, vRBC was reduced by more than 40%. Flow reduction was reversible when the field strength was decreased below the threshold level. In contrast, mean values determined at different exposure levels for the parameters D, Dart, and FVD did not vary by more than 5%.
Blood flow through capillary networks is affected by strong SMFs directed perpendicular to the vessels. Since the influence of SMFs on blood flow in microvessels directed parallel to the field as well as on collateral blood supply could not be studied, our findings should be carefully interpreted with respect to the setting of safety guidelines.
G.B. and S.S. both contributed equally to thie study. This paper is dedicated to Prof. Dr. Wolfgang Weiss on the occasion of 60th birthday. The authors would like to thank R. Matthes (chairman of the standing committee on physics & engineering of the International Commission on Non-Ionizing Radiation Protection, ICNIRP) and G. Ziegelberger (scientific secretary of ICNIRP) helpful discussions as well as S. Dutz (Department of Biomedical Engineering, University of Applied Sciences, Jena) for technical assistance.