Evidence that dl-propranolol increases thymidine kinase activity, cell mitosis, and beta-adrenoceptors during rat liver regeneration.
BACKGROUND
Adrenoceptor stimulation has been described as an important factor in liver regeneration. We examined the effects of the beta-adrenoceptor antagonist, dl-propranolol, during early steps of regeneration after partial hepatectomy in rat.


METHODS
Thymidine kinase (TK) activity, cell mitosis, and beta-adrenoceptors were measured after a single intraperitoneal (i.p.) injection of dl-propranolol (10 mg/kg) immediately following 70% partial hepatectomy. Enzyme activity was measured as [3H] thymidine (dThd) monophosphate; mitotic index was determined after tissue staining, and beta-adrenoceptors were quantified by saturation binding of [3H] dihydroalprenolol. Liver regeneration was followed for 3 days.


RESULTS
dl-Propranolol increased TK activity as early as 12 h postsurgery, after which it leveled off at 24 h and declined at later times; mitotic index increased from 12 to 48 h after injection and beta-adrenoceptors augmented at 24 h compared to partial hepatectomy alone.


CONCLUSIONS
dl-Propranolol up-regulated beta-adrenoceptors early after partial hepatectomy with an increase in TK activity and augmented hepatocyte mitosis. These data may suggest that dl-propranolol modulates, probably via beta-adrenoceptor blockade, early steps of liver regeneration.
Reyes-Salcido
Verónica
V
Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Sede Sur, Mexico City, Mexico.
Villalobos-Molina
Rafael
R
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D022781:Hepatocytes / Q000378:metabolism; D008099:Liver / Q000473:pathology / Q000502:physiology*; D008938:Mitosis; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012038:Regeneration / Q000187:drug effects*; D013937:Thymidine Kinase / Q000378:metabolism*; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D013937:Thymidine Kinase