ABSTRACT
The adrenal gland is a compelling target in the study of hypertension because its secretory products, both medullary and cortical, directly influence endocrine, cardiovascular, and sympathetic function. The adrenal medulla is highly innervated with preganglionic sympathetic fibers and is capable of biosynthesis and secretion of catecholamines (i.e. dopamine, norepinephrine, epinephrine) directly into the circulation through the adrenal vein. The chromaffin cell is the principal cell type of the adrenal medulla and is specialized for biosynthesis, vesicular storage, and regulated secretion of catecholamines. The adrenal cortex envelops the medulla and is the site of biosynthesis and secretion of several classes of steroid hormones, including mineralocorticoids, glucocorticoids, and sex steroids. The zona glomerulosa, zona fasiculata, and zona reticularis constitute the adrenal cortex, and each zone contains histologically and functionally distinct cells that synthesize and secrete mineralocorticoids, glucocorticoids, and sex steroids, respectively. The entire adrenal gland is richly vascularized with a generally centripetal circulation (cortex medulla), and all medullary and cortical secretory products exit the gland through the single, large adrenal vein.
