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.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Endocrinology
2014 ; 155
(1
): 47-55
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Minireview: potassium channels and aldosterone dysregulation: is primary
aldosteronism a potassium channelopathy?
#MMPMID24248457
Gomez-Sanchez CE
; Oki K
Endocrinology
2014[Jan]; 155
(1
): 47-55
PMID24248457
show ga
Primary aldosteronism is the most common form of secondary hypertension and has
significant cardiovascular consequences. Aldosterone-producing adenomas (APAs)
are responsible for half the cases of primary aldosteronism, and about half have
mutations of the G protein-activated inward rectifying potassium channel Kir3.4.
Under basal conditions, the adrenal zona glomerulosa cells are hyperpolarized
with negative resting potentials determined by membrane permeability to K(+)
mediated through various K(+) channels, including the leak K(+) channels TASK-1,
TASK-3, and Twik-Related Potassium Channel 1, and G protein inward rectifying
potassium channel Kir3.4. Angiotensin II decreases the activity of the leak K(+)
channels and Kir3.4 channel and decreases the expression of the Kir3.4 channel,
resulting in membrane depolarization, increased intracellular calcium,
calcium-calmodulin pathway activation, and increased expression of cytochrome
P450 aldosterone synthase (CYP11B2), the last enzyme for aldosterone production.
Somatic mutations of the selectivity filter of the Kir3.4 channel in APA results
in loss of selectivity for K(+) and entry of sodium, resulting in membrane
depolarization, calcium mobilization, increased CYP11B2 expression, and
hyperaldosteronism. Germ cell mutations cause familial hyperaldosteronism type 3,
which is associated with adrenal zona glomerulosa hyperplasia, rather than
adenoma. Less commonly, somatic mutations of the sodium-potassium ATPase, calcium
ATPase, or the calcium channel calcium channel voltage-dependent L type alpha 1D
have been found in some APAs. The regulation of aldosterone secretion is exerted
to a significant degree by activation of membrane K(+) and calcium channels or
pumps, so it is not surprising that the known causes of disorders of aldosterone
secretion in APA have been channelopathies, which activate mechanisms that
increase aldosterone synthesis.