High-intensity static magnetic fields modulate skin microcirculation and temperature in vivo

We investigated the acute effect of static magnetic fields of up to 8 T on skin blood flow and body temperature in anesthetized rats. These variables were measured prior to, during, and following exposure to a magnetic field in a superconducting magnet with a horizontal bore. The dorsal skin was tra nsversely incised for 1 cm to make a subcutaneous pocket. Probes of a laser Doppler flowmeter and a thermistor were inserted into the pocket and posit ioned at mid-dorsum to measure skin blood flow and temperature. Another the rmistor probe was put into the rectum to monitor rectal temperature. After baseline measurement outside the magnet, the rat was inserted into the bore for 20 min so that mid-dorsum was exactly positioned at the center, where the magnetic field was nearly homogeneous. Post-exposure changes were then recorded for 20 min outside the bore. Sham-exposed animals were submitted t o exactly the same conditions, except that the superconducting magnet was n ot energized. Skin blood flow and temperature decreased significantly durin g magnetic field exposure and recovered after removal of the animal from th e magnet. The rectal temperature showed a tendency to decrease while the an imal was in the magnet. The microcirculatory and thermal reactions in the p resent study were consistent and agreed with some of the predictions based on mathematical simulations and model experiments. (C) 2000 Wiley-Liss, Inc .