Electrophysiological studies on the effect of age on caudal nerve of the rat.

The effect of age on electrophysiologic parameters was studied on the caudal nerve of 374 male Sprague-Dawley rats (age 24 to 630 days) and on 83 Fischer 344 rats (age 29 to 900 days). For Sprague-Dawley rats nerve conduction velocity and nerve action potential amplitude were both a parabolic function of age, increasing to 1 year and then declining. For Fischer 344 rats the same parameters increased progressively to 1.5 years and then declined. In contrast, for both Sprague-Dawley and Fischer 344 rats, resistance to ischemic conduction failure was a hyperbolic function of age reaching an asymptote at 1.5 to 2 years of age. These age-related changes in caudal nerve parallel the electrophysiologic alterations with age in human peripheral nerve more closely than previous reports in rodent limb nerves.