Adrenergic Receptor Subtypes& G-Protein Coupled Mechanisms B Adrenergic Receptors Activation of adenyl cyclase through Gs proteins Mechanism increase intracellular camp levels Effects: phosphorylation of intracellular proteins, smooth muscle relaxation cardiac muscle contractionβ Adrenergic Receptors: Activation of adenyl cyclase through Gs proteins Mechanism: increase intracellular cAMP levels Effects: phosphorylation of intracellular proteins, smooth muscle relaxation, cardiac muscle contraction Adrenergic Receptor Subtypes & G-Protein Coupled Mechanisms 8