Heterogenous properties of alpha2 adrenoceptors in particulate and soluble preparations of human platelet and rat and rabbit kidney

Adrenoceptors and Their Second Messenger Systems

“…However, even in the early studies it was evident that there was regional and species variation in the affinity of a-adrenoceptor subtype-selective drugs competing for binding of the a,-adrenoceptor antagonist ligand [3H]rauwolscine (Cheung et al, 1982;Summers et al, 1983;Kawahara and Bylund, 1985;Neylon and Summers, 1985). Subsequent studies with solubilized receptors, eliminating possible contributions from other components of membranes, confirmed these findings (Cheung et al, 1986). The presence of multiple a,-adrenoceptor subtypes is supported by several lines of evidence, the strongest of which are the cloning and sequencing of four a,-adrenoceptors, the development of subtypespecific drugs such as SKF 104078 (Ruff010 et al, 1987), and the characterization of several cell lines that express a single subtype .…”

Delineation of three pharmacological subtypes of α2‐adrenoceptor in the rat kidney

“…This will render the signal from cc2A-adrenoceptors insignificant compared to the signal obtained from the X2B-adrenoceptor subtypes. These findings are consistent with data in the literature suggesting that [3H]-yohimbine (or [3H]-rauwolscine) labels only a2B-adrenoceptors in the rat kidney (Cheung et al, 1986;Michel et al, 1989a).…”

Identification of α2‐Adrenergic Receptors in Chicken Pineal Gland Using [3H]Rauwolscine

“…The evidence that a2-adrenergic receptors from a variety of tissues and species are not a homogeneous group is based on distinct differences in the pharmacological properties of these receptors (Neylon and Summers, 1985;Bylund, 1985;Nahorski et al, 1985;Cheung et al, 1986). We have proposed the subclassification of a2-adrenergic receptors into two subtypes: the a2A' and the azB-adrenergic receptors (Bylund, 1985(Bylund, , 1988b.…”