Effects of insulin, dexamethasone and glucagon on the production of apolipoprotein A-I in cultured rat hepatocytes.
Cultured rat hepatocytes were used to study the effects of hormones on the production of apo A-I. In addition, we compared these effects with the production of albumin. Hepatocytes were isolated from normal adult rat livers and cultured in MEM, as nearly confluent monolayers. In the absence of hormones, apo A-I and albumin accumulated in the culture medium almost linearly for periods up to 24 h. The rates of accumulation of apo A-I and albumin in the medium were 22 ng/mg cell protein per h and 1.2 micrograms/mg cell protein per h, respectively. During the incubations the cellular contents of apo A-I remained constant. Insulin stimulated the production of albumin at concentrations over 10(-10) M, but inhibited the production of apo A-I at concentrations over 10(-8) M. Dexamethasone showed no significant effects on albumin production but stimulated apo A-I production at concentrations over 10(-6) M. Glucagon inhibited the production of albumin and apo A-I dose-dependently at concentrations over 10(-10) M. Thus, the production of albumin and apo A-I are presumably controlled by different regulatory mechanisms.
D000418:Albumins / Q000096:biosynthesis; D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000096:biosynthesis*; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008075:Lipoproteins, HDL / Q000096:biosynthesis*; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D000418:Albumins; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D007328:Insulin; D008075:Lipoproteins, HDL; D003907:Dexamethasone; D005934:Glucagon