Urinary 6-sulphatoxymelatonin excretion of rats is not changed by 24 hours of exposure to a horizontal 50-Hz, 100-μT magnetic field

The effect of exposure to a 50-Hz horizontal magnetic field on the excretion of urinary 6-sulphatoxymelatonin (aMT6s) into nocturnal urine of rats was studied. Two directions of the horizontal magnetic field, parallel and perpendicular to the magnetic north, were investigated in two separate experiments. Twenty-two male Wistar rats were kept in metabolic cages under 9:15 light:dark conditions for 5 days; the nocturnal urine was collected daily. The concentration of aMT6s in the rat urine was measured by I-125-radioimmunoassay. After the first 2 days, the rats were exposed to 100- or 1-mu T flux density magnetic fields for 24 h. On the fourth and fifth days, the urine collection was continued without exposure. It was found that the excretion of aMT6s, the primary urinary metabolite of melatonin, did not show statistically significant alteration during or after 50-Hz horizontal magnetic field exposure of rats to 100 or 1 mu T flux density.