ACUTE TREATMENT WITH PULSED ELECTROMAGNETIC-FIELDS AND ITS EFFECT ON FAST AXONAL-TRANSPORT IN NORMAL AND REGENERATING NERVE

The mechanism whereby low-frequency electromagnetic fields accelerate axonal regrowth and regeneration of peripheral nerve after crush lesio n is not known. One candidate is an alteration in axonal transport. In this study we exposed unoperated rats for 15 min/day, and rats that h ad undergone a crush lesion of the sciatic nerve, for 1 hr/day for 2 d ays, to 2-Hz pulsed electromagnetic fields, To label fast transported proteins, [H-3]-proline was microinjected into the spinal cord, and th e sciatic nerves were removed 2, 3.5, and 5 hr later. The rates of fas t axonal transport were obtained for animals in all groups by counting sequential 2-mm segments of nerves. The following transport rates wer e found: in unoperated normal sciatic nerve not exposed to PEMF, 373 /- 14 mm/day; in unoperated normal nerve exposed to PEMF, 383 +/- 14 m m/day; in sham crush nerves not exposed to PEMF, 379 +/- 19 mm/day; in sham crush nerve exposed to PEMF, 385 +/- 17 mm/day; in crushed nerve s not exposed to PEMF, 393 +/- 16 mm/day; and in crushed nerves expose d to PEMF, 392 +/- 15 mm/day. The results of these experiments indicat e that 1) a crush injury to the sciatic nerve does not alter the rate of fast axonal transport, and 2) low-frequency pulsed electromagnetic fields do not alter fast axonal transport rates in operated (crush) or unoperated sciatic nerves. (C) 1995 Wiley-Liss, Inc.