Study of beta-adrenoceptors and beta-adrenergic responsiveness in cultured "preneoplastic-like" and neoplastic rat hepatocytes.
The presence of specific binding sites for tritiated CGP-12177, a beta-adrenergic antagonist, was investigated in the preneoplastic-like C1I cell-line and in Morris hepatoma MH3924 cells. It was found that C1I cells possess beta-adrenoceptors with the following characteristics: KD = 1.58 +/- 0.56 nM and Bmax = 4.41 +/- 0.88 fmol/10(6) cells. No specific binding sites could be found on MH3924 cells. Stimulation of the C1I cells beta-adrenoceptors by isoprenaline, salbutamol, adrenaline and noradrenaline induced cyclic AMP accumulation. Noradrenaline was, however, a hundred times less efficient than adrenaline, as is the case in normal rat hepatocytes. The order of potency of beta-antagonists either to displace the bound radioligand or to counteract isoprenaline induced cyclic AMP accumulation (IPS-339 greater than propranolol much greater than atenolol) indicates that the adrenoceptors present on the C1I cells are of the beta 2-subtype.
Cortinovis
C
C
Mayer
D
D
Bouscarel
B
B
Paris
H
H
Murat
J C
JC
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000420:Albuterol / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D001667:Binding, Competitive; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis*; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D011230:Precancerous Conditions / Q000378:metabolism*; D011412:Propanolamines / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D011433:Propranolol; D000242:Cyclic AMP; D007545:Isoproterenol; D000420:Albuterol; C033394:CGP 12177; D015056:1-Methyl-3-isobutylxanthine; D009638:Norepinephrine; D004837:Epinephrine