Ratio between arachidonic and linoleic acid of OFA (Sprague Dawley) rats during the exposure to ELF magnetic field in adult and aging animals. Data were estimated at day 1,15, 29, 36 and 50. The region between the dashed lines shows the period of 1 week when the field was turned off. Panel (A) shows the variation in each single rat: it can be observed the extreme variability of the individual response to the external stimulus enhanced for the aging rats. Panel (B) shows the averages of the panel (A) grouped in two subsets. Error bars are ± 1 standard deviation.