| Abstract: | Isoprenaline treatment of C6-glioma cells induced a fast decrease in the number of beta-adrenergic receptors as determined by binding of 3H]CGP-12177, which paralleled the decrease in the hormonally stimulated adenylate cyclase activity. The total number of receptors, as determined by binding of (-)-3H]dihydroalprenolol, did not decrease. Separation of the beta-adrenergic receptors on a sucrose density gradient showed that the decrease in the number of receptors detectable with CGP-12177 was due to a movement of the receptors from the plasma membrane to a vesicular cell compartment. By using both (-)-3H]dihydroalprenolol and 3H]CGP-12177 it is thus possible to differentiate between the total number of receptors and those present at the plasma membrane in an unfractionated cell lysate. |
