Molecular and pharmacological identity of the α2D-adrenergic receptor subtype in bovine photoreceptors

V. Venkataraman, T. Duda, R. K. Sharma

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose. To determine the molecular and pharmacological identity of the adrenergic receptors (AR) in bovine photoreceptors. Methods. The structural and molecular identity of the α2D-AR subtype in the bovine retina was established by reverse transcription-polymerase chain reaction (RT-PCR), and its pharmacological identity in rod outer segments by ligand binding studies. Results. The deduced aa sequence of the two bovine gene fragments, aa residues 290-375 and aa residues 392-434, demonstrates ∼80% overall identity with the rat and mouse α2D-ARs. The encoded-receptor gene was expressed in the photoreceptors with the typical α2D subtype pharmacological characteristics: The receptor bound rauwolscine with a KD of 14 nM in the retina and with that of 19 nM in the photoreceptor cells; the binding association rate constant, k+1, for the ligand was 0.012 min-1, the dissociation rate constant, k-1, was 0.14 min-1 and the half-time for dissociation was 5 min. Oxymetazoline displaced the bound [3H]-rauwolscine with an EC50 value of 85 nM, while SK&F104078 and prazosin displaced the bound [3H]-rauwolscine with the respective IC50 values of 900 nM and 3000 nM. The other α2-AR subtypes - α2A-AR, α2B-AR, α2C-AR - were not detected in the retina and its photoreceptors. Conclusions. The bovine α2D-AR subtype is present in its exclusive form in the bovine photoreceptors, where it may be presynaptic in nature.

Original languageEnglish (US)
Pages (from-to)S808
JournalInvestigative Ophthalmology and Visual Science
Volume37
Issue number3
StatePublished - Feb 15 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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