The effects of 2′-deoxycoformycin on the action of cordycepin on nuclear RNA synthesis in regenerating liver

Abstract

The effect of the adenosine deaminase inhibitor, 2′-deoxycoformycin, upon the inhibitory action of cordycepin on nuclear RNA synthesis was tested in regenerating rat liver 18 hr after partial hepatectomy. The 50% inhibitory effect (ID50) of 2′-deoxycoformycin on adenosine deaminase activity was 6–7 μg/kg in both normal and regenerating liver. Cordycepin inhibited nuclear ribosomal RNA, non-poly(A) heterogeneous nuclear RNA, and poly(A) heterogeneous nuclear RNA at ID50 doses of 15, 18, and 17 mg/kg, respectively, 45 min after treatment. Pretreatment for 10 min with 2′-deoxycoformycin results in a 27–53% decrease in the ID50 of cordycepin for all three species of nuclear RNA. Maximum potentiation by 2′-deoxycoformycin was achieved at 4 hr after cordycepin treatment for nuclear ribosomal RNA and non-poly(A) heterogeneous nuclear RNA and at 45 min for poly(A) heterogeneous nuclear RNA. These results suggest that the deamination of cordycepin is not a highly significant factor in regenerating liver.