IDENTIFICATION AND CHARACTERIZATION OF THE BETA-ADRENERGIC-RECEPTOR ON NEUROBLASTOMA X GLIOMA HYBRID NG108-15 CELLS

1. Using [3H]DHA and unlabeled l-alprenolol, a substantial amount of over 64% specific binding of β-adrenergic receptor has been identified on the neuroblastoma × glioma hybrid NG108-15 cell, which has been proven to display numerous functional characteristics of intact neurons. 2. Beta-adrenergic receptor binding on intact NG108-15 cells does not change significantly upon morphological differentiation, induced by 1 m M dibutyryl cyclic AMP (dBcAMP). 3. The [3H]DHA binding on intact NG108-15 cells is rapid, saturable, and reversible, having a t1/2 of 1.0 min for association and 3.5 min for dissociation. 4. The affinity constant (Kd) and maximum binding capacity (Bmax) for binding of [3H]DHA to β-adrenergic receptors on NG108-15 cells have been estimated by Scatchard plot analysis to be 2.5 and 0.23 n M, respectively. Further analysis indicates a single class of receptors for [3HDHA binding on NG108-15 cells. 5. Studies on kinetic properties have revealed on-rate (K + 1) and off-rate (K - 1) constants of 0.7 × 10-9M min-1 and 0.19 min-1, respectively. Further, the IC50 value and inhibition constant (Ki) for unlabeled l-alprenolol to inhibit [3HDHA binding on NG108-15 cells have been estimated to be 10-5 and 8.9 × 10-6M, respectively. 6. The rank-order potency of catecholamine agonists, (-)ISO > (+)ISO > EPI > NE, reveals the presence of type 2 receptor for the β-adrenergic binding on both differentiated and undifferentiated NG108-15 cells. 7. The present study indicates that the clonal neuroblastoma × glioma hydbrid NG108-15 cell line possesses substantial amounts of β-adrenergic receptors with characteristics similar to those on neuronal cells. © 1990 Plenum Publishing Corporation.