with the aid of three basic organic compounds , 2-pyrazinoylguanidine , 3-amino-2-pyrazinoylguanidine , and 3,5-diamino-6-fluoro-2-pyrazinoylguanidine , urea was shown to be secreted by the renal tubules of the dog both from the lumen and into the lumen independent of urine flow .
C0029224
organic compounds
C0041942
urea