Hormone receptors and sites of action in the kidney

Identification of hormone target sites in the nephron has been achieved in part using autoradiography, and largely with microdissection and microanalysis techniques that permit quantitative measurements of hormone binding or postbinding effects in discrete nephron segments. The nephron target sites of hormones whose intracellular second messenger is known have been located by measuring their stimulatory effect on cyclic AMP or GMP production along the nephron. These hormones include arginine vasopressin, parathyroid hormone, calcitonin, and beta-adrenergic catecholamines. In contrast, the action sites of hormones whose cellular mediators are less well understood have been identified using micro modifications of conventional binding techniques scaled down to the minute (less than or equal to 1 microgram protein) amount of tissue available. In this group are aldosterone, corticosterone, insulin, angiotensin II, alpha-adrenergic catecholamines and dopamine. Atrial natriuretic peptides and glucagon have been studied with both methods. The precise localization of hormone receptors and sites of action in the functionally heterogeneous nephron is critical for understanding the interactions between the kidney and the endocrine system in fluid volume homeostasis, blood pressure control, and in biochemical and metabolic regulation.