Effects of partial hepatectomy on the utilization of 3h-thymidine in mice

Abstract

1. 1. Thymidine availability and specificity for DNA synthesis in various organs of hepatectomized and intact mice and the magnitude of catabolism of administered 3H-thymidine were investigated. 2. 2. The serum thymidine radioactivity 5 min after administration was 1.5 % of the total administered dose. The radioactivity decreased rapidly and was reduced to 1 % of the 5 min value after 2hr. 3. 3. β-AIB accumulated m serum until 20 min after injection and then its level decreased. The levels of thymidine and β-AIB radioactivity were increased 2–3 times after partial hepatectomy. 4. 4. Volatile radioactivity constituted 90% of the total serum radioactivity 60 min after injection. 5. 5. The level of acid soluble radioactivity in liver and kidney was higher, whilst that in spleen, thymus and cerebrum was lower than the serum acid soluble radioactivity until 60 min after injection. Liver and kidney acid soluble radioactivity was increased, but that of spleen, thymus and cerebrum was unaffected by partial hepatectomy. 6. 6. Sixty minutes after injection, the radioactivity in RNA was 1–10% of that in DNA per gram of spleen, thymus and regenerating liver, but 25 and 50 % of that in kidney and intact liver respectively. Incorporation of 3H-activity into liver RNA was increased 48 hr after partial hepatectomy; no difference was obtained in other organs. 7. 7. The main incorporation of 3H-thymidine into DNA was confined to the first 20 min after injection. The DNA radioactivity of the spleen was 2.3 %, thymus 0.4%, kidney 0.2% and that of intact liver 0.6 % of the total injected dose 60 min after injection. Forty-eight hours after partial hepatectomy the DNA radioactivity in the liver was 5 times that of control liver. At 24–72 hr after resection, incorporation of 3H-thymidine into DNA/g of liver was in the same range as that of thymus and spleen. The radioactivity of thymus and kidney DNA was reduced while that of liver DNA was at a maximum.