Tungstate activates BK channels in a β subunit- and Mg2+-dependent manner: relevance for arterial vasodilatation.

Tungstate reduces blood pressure in experimental animal models of both hypertension and metabolic syndrome, although the underlying mechanisms are not fully understood. Given that the large-conductance voltage- and Ca(2+)-dependent K(+) (BK) channel is a key element in the control of arterial tone, our aim was to evaluate whether BK channel modulation by tungstate can contribute to its antihypertensive effect. Patch-clamp studies of heterologously expressed human BK channels (α + β(1-4) subunits) revealed that cytosolic tungstate (1 mM) induced a significant left shift (∼20 mV) in the voltage-dependent activation curve only in BK channels containing αβ(1) or αβ(4) subunits, but reduced the amplitude of K(+) currents through all BK channels tested. The β(1)-dependent activation of BK channels by tungstate was enhanced at cytosolic Ca(2+) levels reached during myocyte contraction, and prevented either by removal of cytosolic Mg(2+) or by mutations rendering the channel insensitive to Mg(2+). A lower concentration of tungstate (0.1 mM) induced voltage-dependent activation of the vascular BKαβ(1) channel without reducing current amplitude, and consistently exerted a vasodilatory action on wild-type but not on β(1)-knockout mouse arteries pre-contracted with endothelin-1. Tungstate activates BK channels in a β subunit- and Mg(2+)-dependent manner and induces vasodilatation only in mouse arteries that express the BK β(1) subunit.

Citation

Ana I Fernández-Mariño, Cristina Porras-González, Patricia González-Rodríguez, Jana Selent, Manuel Pastor, Juan Ureña, Antonio Castellano, Miguel A Valverde, José M Fernández-Fernández. Tungstate activates BK channels in a β subunit- and Mg2+-dependent manner: relevance for arterial vasodilatation. Cardiovascular research. 2012 Jul 1;95(1):29-38

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PMID: 22473360

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