Methylguanidine, guanidinoacetic acid and guanidinosuccinic acid are e
ndogenous substances in body tissues. Extremely high levels,of these s
ubstances are known to be related to the pathogenesis of epilepsy and
renal failure such as uremia. In this study it was demonstrated that m
ethylguanidine, guanidinoacetic acid and guanidinosuccinic acid, acid
arginine generate hydroxyl radicals in aqueous solution. These finding
s suggest that a high level of guanidino compounds accumulating near o
r within cells such as neurons (in an epileptogenic focus) or nephrons
(in uremic patients) may cause free radical damage leading to these c
linical disorders. Arginine may have a similar role in the pathogenesi
s of hyperarginemia.