title: Metabolism and excretion of exogenous adenosine 3':5'-monophosphate and guanosine 3':5'-monophosphate. Studies in the isolated perfused rat kidney and in the intact rat.
abstract: Isolated rat kidneys were perfused with a recirculating medium containing exogenous adenosine 3':5'-monophosphate (cyclic AMP) or guanosine 3':5'-monophosphate (cyclic GMP) at an initial concentration of 0.1 mM. Both cyclic nucleotides were rapidly removed from the perfusate. Urinary excretion accounted for about 20% and 40% of the respective cyclic AMP and cyclic GMP lost from the perfusate. The metabolism of the cyclic nucleotides was studied by 14C-labeled cyclic nucleotides in the perfusate. During 60 min, 30% of added cyclic [14C]AMP was metabolized to renal [14C]adenine nucleotides (ATP, ADP, and AMP) and 30% to perfusate [14C]uric acid. Similarly, 20% of cyclic[14C]GMP was metabolized to renal [14C]guanine nucleotides (GTP, GDP, and GMP) and 30% to perfusate [14C]uric acid. Urine contained principally unchanged 14C-labeled cyclic nucleotide. Addition of 0.1 mM cyclic AMP to the perfusate elevated the renal ATP and ADP contents 2-fold. Addition of 0.1 mM of either cyclic AMP or cyclic GMP to the perfusate also elevated the renal production of uric acid 2- to 3-fold. The production and distribution of metabolites of exogenous cyclic nucleotides were also studied in the intact rat. Within 60 min after injection, 3.3 mumol of either 14C-labeled cyclic AMP or cyclic GMP was cleared from the plasma. Kidney cortex and liver were the principal tissues for 14C accumulation. Urinary excretion accounted for about 20 and 45% of the cyclic [14C]AMP and cyclic [14C]GMP lost from the plasma, respectively. The 14C found in the kidney and liver was present almost entirely as the respective purine mono-, di-, and trinucleotides. The other principal metabolite was [14C]allantoin, found in the urine and, to a lesser extent, the liver. The urine contained mostly unchanged 14C-labeled cyclic nucleotide. Unlike the findings with the perfused kidney, [14C]uric acid was not a significant metabolite of the 14C-labeled cyclic nucleotides in these in vivo experiments.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000481:Allantoin / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism* / Q000652:urine; D006152:Cyclic GMP / Q000378:metabolism* / Q000652:urine; D007042:Hypoxanthines / Q000378:metabolism; D066298:In Vitro Techniques; D007288:Inosine / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D010477:Perfusion; D051381:Rats; D014970:Xanthines / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D007042:Hypoxanthines; D014970:Xanthines; D000481:Allantoin; D007288:Inosine; D000242:Cyclic AMP; D006152:Cyclic GMP