The alpha 2-adrenoceptors of the human retinoblastoma cell line (Y79) may represent an additional example of the alpha 2C-adrenoceptor.
1. In agreement with the literature, correlation of the ability of a series of agonists and antagonists to displace [3H]-rauwolscine binding shows the alpha 2-adrenoceptors of HT29 cells, NG108-15 cells, OK cells and homogenates of rat sublingual gland to represent four distinct subtypes. 2. [3H]-rauwolscine also bound with high affinity (KD = 0.30 +/- 0.10 mM) to a human retinoblastoma cell line (Y79). Specific binding represents 73% of total binding, and a Bmax of 38 +/- 1 fmol mg-1 protein was determined. 3. Correlation of antagonist affinities against [3H]-rauwolscine with corresponding values in the other four tissue sources showed the Y79 cells to resemble most closely the OK cells, the prototype example of an alpha 2C-adrenoceptor, with a correlation coefficient of 0.90 and a regression slope of 1.01 being obtained for 10 antagonists in these two systems. 4. Comparison of KD values for [3H]-rauwolscine also showed a similarity between the OK cells (0.19 +/- 0.07 nM) and Y79 cells. 5. These data suggest that the human retinoblastoma cell line may represent an additional example of the alpha 2C-adrenoceptor subtype.
Department of Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406.
M M
MM
Gleason
J P
JP
Hieble
D000316:Adrenergic alpha-Agonists / Q000378:metabolism / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D006801:Humans; D011869:Radioligand Assay; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012175:Retinoblastoma / Q000378:metabolism*; D013361:Sublingual Gland / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015016:Yohimbine / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine