Aim: To examine the subcellular distribution of the 3 alpha1-adrenoceptor (alpha1-AR) subtypes and their internalization and trafficking upon agonist stimulation in human embryonic kidney 293A cells.
Methods: Confocal real-time imaging, enzyme linked immunosorbent assay (ELISA) and whole cell [3H]-prazosin binding assay were applied to detect the distribution and localization of the 3 alpha1-AR subtypes.
Results: alpha1A-AR was found both on the cell surface and in the cytoplasm; alpha1BAR, however, was predominantly detected on the cell surface, while alpha1D-AR was detected mainly in the intracellular compartments. After stimulation with phenylephrine, localization changes were detected by confocal microscopy for alpha1A- and alpha1B-AR,but the localization of alpha1D-AR were unaffected. Phenylephrine stimulation promoted a more rapid internalization of alpha1B-AR than alpha1A-AR. alpha1D-AR internalization was detected only by ELISA. Whole cell [3H]-prazosin binding assay showed that alpha1A-AR functional receptors were detected both on the cell surface and in the cytoplasm; alpha1B-AR, however, were detected predominantly on the cell surface, while alpha1D-AR were detected mainly in intracellular compartments. Phenylephrine stimulation promoted internalization of alpha1A- and alpha1B-AR.
Conclusion: Phenylephrine stimulation induced changes in the localization of the 3 alpha1-AR.