pyrophosphate and Ascites

The concentration of 99mTc-pyrophosphate was determined in the lower extremities of rabbits (normal, abacterial and bacterial affected soft tissues), in osteoarthritis of the hip joint (capsule and muscle) as well as in knee joint effusions. Compared with the 85Sr-concentration, reflecting the calcification capacity, concentrations of 99mTc-pyrophosphate in soft tissues were found to be lower 2 hours p.i., but were up to elevenfold higher 24 hours p.i. These findings should be due to a fixation of 99mTc-pyrophosphate in collagen containing tissues as in the soft tissue tumors (myosarcoma, synvialioma, breast cancer) presented. A mechanism of delayed equilibration could explain augmented uptake in lymph-edema, ascites and effusions in florid osteoarthritis of the knee joint. The possible dependence of 99mTc-pyrophosphate concentration in bone and soft tissue on collagenous contents is discussed.

Topics: Animals; Ascites; Bone and Bones; Breast Neoplasms; Diphosphates; Disease Models, Animal; Extremities; Freund's Adjuvant; Hip; Humans; Joint Diseases; Joint Prosthesis; Joints; Knee; Osteoarthritis; Phosphates; Rabbits; Rhabdomyosarcoma; Sarcoma, Synovial; Strontium; Strontium Radioisotopes; Technetium; Tibial Fractures; Time Factors; Tin

1. The formation of adenosine 5'-phosphate, guanosine 5'-phosphate and inosine 5'-phosphate from [8-(14)C]adenine, [8-(14)C]guanine and [8-(14)C]hypoxanthine respectively in the presence of 5-phosphoribosyl pyrophosphate and an extract from Ehrlich ascites-tumour cells was assayed by a method involving liquid-scintillation counting of the radioactive nucleotides on diethylaminoethylcellulose paper. The results obtained with guanine were confirmed by a spectrophotometric assay which was also used to assay the conversion of 6-mercaptopurine and 5-phosphoribosyl pyrophosphate into 6-thioinosine 5'-phosphate in the presence of 6-mercaptopurine phosphoribosyltransferase from these cells. 2. At pH 7.8 and 25 degrees the Michaelis constants for adenine, guanine and hypoxanthine were 0.9 mum, 2.9 mum and 11.0 mum in the assay with radioactive purines; the Michaelis constant for guanine in the spectrophotometric assay was 2.6 mum. At pH 7.9 the Michaelis constant for 6-mercaptopurine was 10.9 mum. 3. 25 mum-6-Mercaptopurine did not inhibit adenine phosphoribosyltransferase. 6-Mercaptopurine is a competitive inhibitor of guanine phosphoribosyltransferase (K(i) 4.7 mum) and hypoxanthine phosphoribosyltransferase (K(i) 8.3 mum). Hypoxanthine is a competitive inhibitor of guanine phosphoribosyltransferase (K(i) 3.4 mum). 4. Differences in kinetic parameters and in the distribution of phosphoribosyltransferase activities after electrophoresis in starch gel indicate that different enzymes are involved in the conversion of adenine, guanine and hypoxanthine into their nucleotides. 5. From the low values of K(i) for 6-mercaptopurine, and from published evidence that ascites-tumour cells require supplies of purines from the host tissues, it is likely that inhibition of hypoxanthine and guanine phosphoribosyltransferases by free 6-mercaptopurine is involved in the biological activity of this drug.

Topics: Adenine; Adenine Nucleotides; Adenosine Monophosphate; Animals; Ascites; Carcinoma, Ehrlich Tumor; Diphosphates; Electrophoresis; Enzyme Inhibitors; Glucosyltransferases; Guanine; Guanine Nucleotides; Hypoxanthines; Kinetics; Mercaptopurine; Nucleotides; Pharmacology; Purines; Research; Spectrophotometry; Transferases; Xanthines

Topics: Adenine; Adenosine Triphosphate; Animals; Antimetabolites; Ascites; Carbon Isotopes; Diphosphates; Metabolism; Mice; Neoplasms; Neoplasms, Experimental; Nucleosides; Nucleotides; Phosphoribosyl Pyrophosphate; Research; Tissue Culture Techniques; Xylose

Topics: Adenosine Triphosphate; Animals; Ascites; Carbohydrate Metabolism; Carbohydrates; Carcinoma; Carcinoma, Ehrlich Tumor; Diphosphates; Erythrocytes; Glucose; Insulin; Metabolism; Neoplasms, Experimental; Pharmacology; Poultry; Research

Topics: Adenosine Triphosphate; Animals; Ascites; Carcinoma; Carcinoma, Ehrlich Tumor; Diphosphates; Mice; Radiation-Sensitizing Agents; Vitamin K

Topics: Animals; Ascites; Carcinoma, Ehrlich Tumor; Diphosphates; Mice; Neoplasms, Experimental; Radiation-Sensitizing Agents; Vitamin K