Figure 4.
Effect of NPY on localization of α1A-adrenergic receptors. Confocal micrographs show the localization of the α1A-adrenergic receptor in LLCPK cells. (a) In untreated cells, the α1A-adrenergic receptor immunofluorescence signal was found throughout the cell. (b) In sections in which the primary antibody had been preabsorbed with the peptide against which the antibody was raised, there was no detectable fluorescence signal. (c) After treatment with the α1A-adrenergic receptor agonist phenylephrine (10−6 M) for 10 s, a distinct signal was observed in the region of the plasma membrane. (d) After 60 s, α1A-adrenergic receptor immunofluorescence signal was again observed throughout the cell. (e) The relocalization of the α1A-adrenergic receptors at 10 s was not observed in cells pretreated with the α1A-adrenergic receptor antagonist prazosin (10−6 M). Incubation with phenylephrine (10−10 M) alone (f) or NPY (10−10 M) alone (g) for 10 s had no effect on receptor localization, but when applied in combination (h), there was a marked and rapid increase of the α1A-adrenergic receptor signal in the region of the plasma membrane. (i) This effect was sustained for at least 5 min. (j) Incubation with NPY (10−8 M) alone for 10 s caused a rapid relocalization of the α1A-adrenergic receptors to the region of the plasma membrane. (k) This effect was sustained for at least 5 min. (l) The effect of NPY (10−8 M) at 10 s was not seen in cells pretreated with the α1-adrenergic receptor antagonist prazosin (10−6 M).