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Open Access Publications from the University of California

Vascular Reactivity Profile of Novel KCa 3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed.

  • Author(s): Oliván-Viguera, Aida
  • Valero, Marta Sofía
  • Pinilla, Estéfano
  • Amor, Sara
  • García-Villalón, Ángel Luis
  • Coleman, Nichole
  • Laría, Celia
  • Calvín-Tienza, Víctor
  • García-Otín, Ángel-Luis
  • Fernández-Fernández, José M
  • Murillo, M Divina
  • Gálvez, José A
  • Díaz-de-Villegas, María D
  • Badorrey, Ramón
  • Simonsen, Ulf
  • Rivera, Luis
  • Wulff, Heike
  • Köhler, Ralf
  • et al.

Opening of intermediate-conductance calcium-activated potassium channels (KC a 3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KC a 3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KC a 3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KC a currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KC a 3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KC a 3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KC a 3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KC a 3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease.

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