title: Early increase in diadenosine tetraphosphate in regenerating rat liver.
abstract: Diadenosine tetraphosphate (Ap4A), a candidate for a signal molecule in the induction of DNA synthesis, was measured in regenerating livers of young adult rats at 12 and 24 h and of older rats at 24 h after partial hepatectomy. dATP and dTTP levels, which indicate the degree of proliferation in the livers, were determined by high-performance liquid chromatography and an enzymatic method, respectively. The Ap4A levels were increased in the beginning of DNA synthesis. In young rats the levels were about 140% of those of unoperated rats and in older rats about 300%. This increase was considerably smaller than that found in another study comprising two regenerating rat livers excised 20 h after partial hepatectomy, but still supports the hypothesis that Ap4A might take part in the onset of proliferation. The greater Ap4A increase in older rats may suggest a possible need for a stronger triggering mechanism to start proliferation in aged tissue. However, the experiments do not prove a function for Ap4A in the induction of DNA synthesis and it cannot be excluded that Ap4A is a product of an independent reaction.
authors: Department of Zoophysiology, University of Lund, Sweden.
authors: M
authors: M
authors: Andersson
authors: L
authors: L
authors: Lewan
mesh_terms: D000227:Adenine Nucleotides / Q000096:biosynthesis*; D000818:Animals; D002455:Cell Division; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000096:biosynthesis; D003838:Deoxyadenine Nucleotides / Q000032:analysis; D015226:Dinucleoside Phosphates; D008099:Liver / Q000378:metabolism*; D008115:Liver Regeneration; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013942:Thymine Nucleotides / Q000032:analysis; D014544:Uridine Triphosphate / Q000032:analysis
chemical_list: D000227:Adenine Nucleotides; D003838:Deoxyadenine Nucleotides; D015226:Dinucleoside Phosphates; D013942:Thymine Nucleotides; C020733:diadenosine tetraphosphate; D004247:DNA; C026600:2'-deoxyadenosine triphosphate; C024157:thymidine 5'-triphosphate; D014544:Uridine Triphosphate