Effect of magnetic field on the contractility and glycogen content in neuromuscular preparation

The influence of static homogeneous magnetic fields, ranging from zero to 10,000 Oe, was measured on isolated frog neuromuscular preparation. On the fatigue curve, exposure of 10,000 Oe caused the tension development to intensify gradually for the first 1-3 min and the time reached to a fatigued-muscle, not responsive to electrical stimulation, was reduced significantly (P less than 0.05) in comparison with control. No change in muscle surface temperature or in decrease in the rate of glycogen contents could be obtained either in exposed-muscle or in control. Calcium pumping action on the intracellular membrane of exposed-muscle was discussed.