Elevated blood pressure linked to primary hyperaldosteronism and impaired vasodilation in BK channel-deficient mice
Abnormally elevated blood pressure is the most prevalent risk factor for cardiovascular disease. The large-conductance, voltage- and Ca2+-dependent K+ (BK) channel has been proposed as an important effector in the control of vascular tone by linking membrane depolarization and local increases in cyt...
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Veröffentlicht in: | Circulation (New York, N.Y.) N.Y.), 2005-07, Vol.112 (1), p.60-68 |
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Zusammenfassung: | Abnormally elevated blood pressure is the most prevalent risk factor for cardiovascular disease. The large-conductance, voltage- and Ca2+-dependent K+ (BK) channel has been proposed as an important effector in the control of vascular tone by linking membrane depolarization and local increases in cytosolic Ca2+ to hyperpolarizing K+ outward currents. However, the BK channel may also affect blood pressure by regulating salt and fluid homeostasis, particularly by adjusting the renin-angiotensin-aldosterone system.
Here we report that deletion of the pore-forming BK channel alpha subunit leads to a significant blood pressure elevation resulting from hyperaldosteronism accompanied by decreased serum K+ levels as well as increased vascular tone in small arteries. In smooth muscle from small arteries, deletion of the BK channel leads to a depolarized membrane potential, a complete lack of membrane hyperpolarizing spontaneous K+ outward currents, and an attenuated cGMP vasorelaxation associated with a reduced suppression of Ca2+ transients by cGMP. The high level of BK channel expression observed in wild-type adrenal glomerulosa cells, together with unaltered serum renin activities and corticotropin levels in mutant mice, suggests that the hyperaldosteronism results from abnormal adrenal cortical function in BK(-/-) mice.
These results identify previously unknown roles of BK channels in blood pressure regulation and raise the possibility that BK channel dysfunction may underlie specific forms of hyperaldosteronism. |
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ISSN: | 0009-7322 1524-4539 |
DOI: | 10.1161/01.CIR.0000156448.74296.FE |