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

The effect of exposure to a 50-Hz horizontal magnetic field on the excretio n of urinary 6-sulphatoxymelatonin (aMT6s) into nocturnal urine of rats was studied. Two directions of the horizontal magnetic field, parallel and per pendicular to the magnetic north, were investigated in two separate experim ents. Twenty-two male Wistar rats were kept in metabolic cages under 9:15 l ight:dark conditions for 5 days; the nocturnal urine was collected daily. T he concentration of aMT6s in the rat urine was measured by I-125-radioimmun oassay. After the first 2 days, the rats were exposed to 100- or 1-mu T flu x 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 statis tically significant alteration during or after 50-Hz horizontal magnetic fi eld exposure of rats to 100 or 1 mu T flux density.