The zona glomerulosa (sometimes, glomerular zone) of the
adrenal gland is the most superficial layer of the
adrenal cortex, lying directly beneath the
renal capsule. Its cells are ovoid and arranged in clusters or arches (glomus is
Latin for "ball").[citation needed]
In response to increased
potassium levels,
renin or decreased
blood flow to the
kidneys, cells of the zona glomerulosa produce and secrete the
mineralocorticoidaldosterone into the blood as part of the
renin–angiotensin system.[1] Although sustained production of aldosterone requires persistent
calcium entry through low-voltage activated
Ca2+ channels, isolated zona glomerulosa cells are considered nonexcitable, with recorded membrane voltages that are too hyperpolarized to permit
Ca2+ channels entry.[2] However, mouse zona glomerulosa cells within adrenal slices spontaneously generate membrane potential oscillations of low periodicity; this innate
electrical excitability of these cells provides a platform for the production of a recurrent Ca2+ channels signal that can be controlled by
angiotensin II and extracellular
potassium, the 2 major regulators of aldosterone production.[2] Aldosterone regulates the body's concentration of
electrolytes, primarily
sodium and potassium, by acting on the
distal convoluted tubule of kidney
nephrons to: increase sodium reabsorption, increase potassium
excretion, increase water reabsorption through
osmosis.[1]
The enzyme
aldosterone synthase (also known as
CYP11B2) acts in this location[3][4] The expression of neuron-specific proteins in the zona glomerulosa cells of human adrenocortical tissues has been predicted and reported by several authors[5][6][7] and it was suggested that the expression of proteins like the
neuronal cell adhesion molecule (NCAM) in the cells of the zona glomerulosa reflects the regenerative feature of these cells, which would lose NCAM immunoreactivity after moving to the zona fasciculata.[5][8] However, together with other data on neuroendocrine properties of zona glomerulosa cells, NCAM expression may reflect a neuroendocrine differentiation of these cells.[5]Voltage-dependent calcium channels have been detected in the zona glomerulosa of the human adrenal, which suggests that
calcium-channel blockers may directly influence the adrenocortical biosynthesis of
aldosterone in vivo.[9]
^Zhou, M.Y.; Gomez-Sanchez, C.E. (1993). "Cloning and Expression of a Rat Cytochrome P-450 11β-Hydroxylase/Aldosterone Synthase (CYP11B2) cDNA Variant". Biochemical and Biophysical Research Communications. 194 (1): 112–7.
doi:
10.1006/bbrc.1993.1792.
PMID8333830.