Alpha 1-adrenergic receptors in liver regeneration.
The alpha 1-adrenergic receptor mediates the effects of catecholamines on DNA synthesis, as observed in rat liver following a 2/3 partial hepatectomy and in serum-free primary cultures of adult rat hepatocytes exposed to epidermal growth factor. In vitro, norepinephrine action at this receptor heterologously down-regulates epidermal growth factor receptors. In vivo, the alpha 1 receptor's effect on DNA synthesis is restricted to early time points after partial hepatectomy. alpha 1 receptor binding capacity does not vary until 48 hr after liver resection (at which time binding is reduced), but an uncoupling of receptor binding from membrane phosphoinositide turnover occurs between 8 and 16 hr after partial hepatectomy. This change is preceded by a fall in membrane-associated ras p21 detected by radioimmunoassays (46% of control levels by 2 hr after partial hepatectomy). Whether this change represents a loss of p21 protein from membranes or a modification that results in a loss of immunoreactivity is not known.
Cruise
J L
JL
Department of Biology, College of St. Thomas, St. Paul, Minnesota 55105.
D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006498:Hepatectomy; D008115:Liver Regeneration / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D015689:Oncogene Protein p21(ras) / Q000378:metabolism; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*
D011942:Receptors, Adrenergic, alpha; D004815:Epidermal Growth Factor; D004247:DNA; D015689:Oncogene Protein p21(ras); D009638:Norepinephrine; D011224:Prazosin