Molecular and pharmacological characterization of the canine brainstem alpha-2A adrenergic receptor

This study characterizes the alpha2-adrenergic receptors present in canine brainstem. Radioligand binding and reverse transcriptase-polymerase chain reaction (RT-PCR) experiments were performed in canine brainstem to identify the receptors present and determine the pharmacological properties of these receptors. The pKi values derived from radioligand competition curves for a number of adrenergic receptor agents at the four alpha2-adrenergic receptor subtypes were compared to the canine brainstem. The pKi values at the canine brainstem alpha2-adrenergic receptor were consistent with the presence of the alpha2A-adrenergic receptor. To determine whether the canine brainstem expressed the message for the alpha2A-adrenergic receptor, RT-PCR was performed with specific primers for the four subtypes of alpha2-adrenergic receptors. In the canine brainstem, only the primers corresponding to a region in the human alpha2A-adrenergic receptor produced a PCR product. No bands were detected in the canine brainstem lanes with the alpha2B-, alpha2C-, or alpha2D-receptor primers. These data suggest that the canine brainstem contains the alpha2A-adrenergic receptor.