Acute regulation of hepatic lipase secretion by rat hepatocytes.
Hepatic lipase is involved in cholesterol uptake by the liver. Although it is known that catecholamines are responsible for the daily variation of enzyme activity, the mechanisms involved are poorly understood. Rat hepatocytes incubated with adrenaline or other Ca(2+)-mobilizing hormones were used as an experimental model. Adrenaline reduced in a similar proportion the secretion of both hepatic lipase and albumin. The effect of adrenaline disappeared completely in cells exposed to cycloheximide. Adrenaline decreased incorporation of [35S]Met into cellular and secreted proteins, but it affected neither degradation of [35S]Met-prelabeled proteins nor the abundance of total and specific (albumin, hepatic lipase, beta-actin) mRNA. Other Ca(2+)-mobilizing agents had the opposite effect on hepatic lipase secretion: it was decreased by vasopressin but was increased by epidermal growth factor. Vasopressin and epidermal growth factor had the opposite effect on [35S]Met incorporation into cellular and secreted proteins, but neither affected hepatic lipase mRNA. The acute effect of adrenaline, vasopressin, and epidermal growth factor on hepatic lipase secretion is the consequence of the effect of these hormones on protein synthesis and is therefore nonspecific.
Galan
Xavier
X
Peinado-Onsurbe
Julia
J
Robert
Monique Q
MQ
Soley
Maria
M
Llobera
Miquel
M
Ramírez
Ignasi
I
D000322:Adrenergic Agonists / Q000494:pharmacology; D000418:Albumins / Q000096:biosynthesis / Q000187:drug effects; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D008049:Lipase / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008715:Methionine / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D013462:Sulfur Radioisotopes / Q000378:metabolism
D000322:Adrenergic Agonists; D000418:Albumins; D011500:Protein Synthesis Inhibitors; D013462:Sulfur Radioisotopes; D003513:Cycloheximide; D008715:Methionine; D008049:Lipase; D002118:Calcium; D004837:Epinephrine