Dose-dependent down-regulation of beta-adrenoceptors by isoproterenol in rat C6 glioma cells.
Nano- and micromolar isoproterenol concentrations were compared by studying cyclic AMP, beta-adrenoceptor density and beta 1-adrenoceptor mRNA in rat C6 glioma cells. 1 microM isoproterenol significantly changed all parameters at 15-30 min. The beta 1-antagonist metoprolol attenuated the response. No effects of nanomolar isoproterenol on these early changes were observed, although the density of beta-adrenoceptors was significantly reduced beginning at 12 h. The results indicate a different process for beta-adrenoceptor desensitization in C6 cells following physiologically low agonist concentrations.
Bieck
P R
PR
Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN 37232.
Duhl
D M
DM
Eiring
A
A
Gillespie
D D
DD
Manier
D H
DH
Sulser
F
F
D000818:Animals; D000242:Cyclic AMP / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005910:Glioma / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D007545:Isoproterenol