Circadian variations of N-acetyl-beta-D-glucosamidase (NAG, EC 3.2.1.3
0) and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) were exam
ined in dogs. Urine and blood were collected at 4-hr intervals from ad
ult mongrel dogs (11 males, 11 females) weighing between 7 and 13 kg.
The collected urine and blood were used to measure creatinine, NAG and
gamma-GTP. The amount of urine was significantly higher (p<0.05) duri
ng the period from 12:00 to 16:00. Creatinine clearance did not show a
ny characteristic variations and creatinine excretion was significantl
y higher (p<0.05) during the period from 8:00 to 16:00. No characteris
tic variations were observed in the amounts excreted, activity, or NAG
and gamma-GTP creatinine index. There were high correlations between
creatinine excretion and creatinine clearance (r=0.693), gamma-GTP exc
retion and gamma-GTP creatinine index (r=0.724), NAG excretion and NAG
creatinine index (r=0.878), and between the NAG and gamma-GTP creatin
ine index of each 4-hr specimen and the NAG and gamma-GTP excretion of
the 24-hr specimens. These results suggest the diagnostic usefulness
measuring enzyme activity in non-periodically collected urine.