Little vessels react to magnetic switch

From San Diego, at the Experimental Biology 2003 meeting

In laboratory animals, a magnet can act like a switch to either open or constrict tiny blood vessels, researchers report. Although preliminary, their study suggests the prospect of using magnets to alter blood flow in damaged tissue.

To look for vascular responses to magnets, biomedical engineer Thomas Skalak of the University of Virginia in Charlottesville obtained a grant from the National Institutes of Health and recruited electrical engineer Cassandra E. Morris, also at U. Va. “I was initially quite skeptical” of finding an effect, says Morris.

In the experiments, she cut thin layers of rat muscle and folded them away from the body so that blood vessels, just 10 to 100 micrometers in diameter, continued to nourish them. Next, she measured the blood vessels’ diameters before and after 15-minute exposures to a static, 700-gauss magnetic field.

Initially, “it looked like nothing happened,” Morris says, because the overall blood flow didn’t appear altered. On closer inspection, however, she found that vessels that had initially been dilated became constricted, and those that had been constricted were dilated. Her team is now trying to find the mechanism for the switch.

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