Assays of Adrenergic Receptors: Including Lipolysis and Binding Measurements

Adipocytes express the three major types of adrenoceptors (ARs), α₁ -, α₂ -, and β-ARs, each of them being further divided into three subtypes. With the exception of α_1A -, α_1B -, and α_1D -ARs, which have not been described to directly influence cAMP production in fat cells, all the other AR subtypes are known to interact with the regulation of lipolytic activity through stimulatory (β₁ -, β₂ -, and β₃ -ARs) or inhibitory (α_2A/D -, α_a2C -, and putatively α_2B -ARs) G-protein-coupled mechanisms (reviewed in ref. 1 ). This explains why, besides their direct quantification by radioligand-binding analyses, the assays on ARs described in this chapter will also include the measurement of one of the biological effects they regulate: lipolysis.