30] Production and application of an antibody specific for the cardiac β-adrenergic receptor

Abstract

Publisher Summary This chapter discusses the production and application of an antibody specific for the cardiac β-adrenergic receptor. Different subclasses of β-adrenergic receptors have been classified, by pharmacological studies, using a variety of agonists and antagonists. In addition to the different subclases of β receptors, there are apparent differences in receptor affinity for agonists in the presence or absence of guanyl nucleotides, implying different conformations of a given receptor and possible functional differences of a given receptor type when coupled to its effector enzyme, adenylate cyclase. Propranolol binding to the cardiac membranes is effectively inhibited by antiserum. Maximal inhibition is equivalent to that of 10 μM 1-isoproterenol. Equivalent results are obtained whether the antiserum or propranolol are first allowed to equilibrate with membranes, suggesting competition between antibody and propranolol for the membrane binding site. The effect of immunoglobulin fractions on adenylate cyclase activity is described in the chapter. The results of incubation of solubilized adenylate cyclase, with preimmune and immune fraction I, are also discussed in the chapter. It is found that there is no evidence of inhibition of either basal or stimulated adenylate cyclase activity by immune globulin, indicating an absence of antibody specific for the catalytic site of the enzyme.