Possible cyclic AMP-dependence of the prereplicative surge of cytosolic calmodulin in proliferatively activated rat liver cells.
The infusion of a solution containing triiodothyronine, amino acids, glucagon, and heparin (TAGH solution) triggered rat liver cell proliferation. It also induced a transient prereplicative surge of cytosolic calmodulin (between 6 and 20 hr postinfusion) similar to that observed in liver cells proliferatively activated by partial hepatectomy. The injection of the beta-adrenergic blocker dl-propanolol (20 mg/kg of body weight) at the time of the infusion prevented this transient rise of cytosolic calmodulin and also inhibited the early prereplicative surge of total liver cyclic AMP, which usually occurred between 1 and 4 hr after infusion. Propanolol also inhibited the early prereplicative surge of cyclic AMP and the increase of calmodulin in liver cells proliferatively activated by partial hepatectomy. The infusion of a solution containing cyclic AMP (5 mumoles) and theophylline (10 mg) into normal rats produced an increase of cytosolic calmodulin similar to that observed after infusion of TAGH solution or after partial hepatectomy. Thus it seems that the prereplicative rise of cytosolic calmodulin observed in proliferatively activated liver cells may be regulated by the early prereplicative surge of cyclic AMP.
Soriano
M
M
Departamento de Biologia Celular, Facultad de Medicina, Universidad de Barcelona, Spain.
Pujol
M J
MJ
Bachs
O
O
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D007700:Kinetics; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008115:Liver Regeneration; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013806:Theophylline / Q000494:pharmacology
D002147:Calmodulin; D011433:Propranolol; D013806:Theophylline; D000242:Cyclic AMP