The effects of 50 Hz magnetic fields on opioid peptide mediated inhibition of guinea pig ileum

Strips of guinea pig ileum were mounted in a tissue bath within the poles of a magnet capable of generating a 50 Hz field of intensity up to 1 mT. In the absence of magnetic field the preparations were stimulated transmurally at tetanic frequency (10 Hz). The post-tetanic inhibition was antagonised by naloxone. When this inhibitory phase was repeated in the presence of a magnetic field of 0.5 mT there was a small but significant increase in the inhibition when compared with paired controls.