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The concentrations of guanidino compounds were determined in urine, plasma and cerebrospinal fluid of two patients with hyperargininemia during dietary therapy. alpha-Keto-delta-guanidinovaleric acid, N-alpha-acetylarginine, argininic acid and gamma-guanidinobutyric acid were increased in urine. In plasma, these compounds together with creatine, guanidinoacetic acid, arginine and homoarginine were also increased. In cerebrospinal fluid, only arginine, homoarginine and argininic acid were increased. Trace amounts of alpha-keto-delta-guanidinovaleric acid were found in cerebrospinal fluid of the patient treated with only a low-arginine diet. The concentrations of guanidinosuccinic acid are decreased in urine, plasma and cerebrospinal fluid. During a low-arginine diet, together with sodium benzoate therapy, the plasma and cerebrospinal fluid arginine values returned to normal. There was also a normalization of plasma guanidinoacetic acid and a marked decrease in plasma N-alpha-acetylarginine and argininic acid.

The levels of 12 guanidino compounds were determined in serum and brain of audiogenically sensitive rats with and without seizures. During audiogenic seizures the serum levels of creatine are significantly decreased, while those of guanidinoacetic acid, N-alpha-acetylarginine, creatinine, gamma-guanidinobutyric acid, arginine, guanidine and methylguanidine are significantly increased. In brain only creatinine and N-alpha-acetylarginine are markedly increased during seizure. These data demonstrate noticeable modifications of the levels of guanidino compounds in the blood during audiogenic seizure and also, in parallel, a creatinine increase in serum and brain.

The levels of 12 guanidino compounds were determined in the serum and brain of mouse, rat, rabbit, and man using cation-exchange column chromatography with the fluorescence ninhydrin detection method. A comparative study of these compounds was made in the four groups studied, for serum and brain. In rabbit and man the different guanidino compounds were also determined in various brain regions. This study provides basic analytical data that could facilitate the interpretation of further biochemical and neurochemical studies dealing with guanidino compounds that are identified as being toxins in hyperargininemia and uremia.