title: The binding of [3H]prazosin and [3H]clonidine to rat jejunal epithelial cell membranes.
abstract: The binding of [3H]prazosin and [3H]clonidine to rat jejunal epithelial cell membranes has been studied. The membrane preparation was enriched in baso-lateral components as determined by Na+, K+ ATPase and alkaline phosphatase activities. The membranes possessed two saturable specific binding sites for [3H]prazosin, a high affinity (Kd 0.17 nM) low capacity (Bmax 27.3 fmole bound per mg protein) and a low affinity (Kd 5.0 nM) high capacity (Bmax 276 fmole bound per mg protein) site. The specificity of both sites was similar and was related to alpha 1-adrenoceptors. [3H]Clonidine bound to the membranes in a saturable fashion (Kd 7.3 nM). The specificity of this site was related to alpha 2-adrenoceptors. The [3H]clonidine binding site was present in the membranes in much lower density (Bmax 22.8 fmole bound per mg protein) suggesting that alpha 1-adrenoceptors predominate in this tissue.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D003000:Clonidine / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011224:Prazosin / Q000378:metabolism*; D011799:Quinazolines / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism
chemical_list: D011799:Quinazolines; D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D011224:Prazosin