Inter-Relations between β-Adrenergic Receptors, Adenylate Cyclase and Calcium

THE catecholamines are a group of hormones that affect most tissues, not only in human beings, but in almost all animal phyla.¹ Whether they are released locally by certain nerve endings or into the general circulation by the adrenal medulla, circulating catecholamines, such as epinephrine and norepinephrine, may regulate basic cellular processes like ion transport, enzyme secretion, glycogenolysis, lipolysis and muscle contraction.² An understanding of their action is therefore needed for an understanding of a variety of cellular activities. In early studies, extracts of the adrenal medulla were injected into intact animals, and physiologic responses such as blood pressure were.