Calcium Sensitization Induced by Sodium Fluoride in Permeabilized Rat Mesenteric Arteries

Calcium Sensitization Induced by Sodium Fluoride in Permeabilized Rat Mesenteric Arteries

It was hypothesized that NaF induces calcium sensitization in Ca^2＋-controlled solution in permeabilized rat mesenteric arteries. Rat mesenteric arteries were permeabilized with Ղ- escin and subjected to tension measurement. NaF potentiated the concentration-response curves to Ca^2＋ (decreased EC₅₀ and increased E_max). Cumulative addition of NaF (4.0, 8.0 and 16 mM) also increased vascular tension in Ca^2＋-controlled solution at pCa 7.0 or pCa 6.5, but not at pCa 8.0. NaF-induced vasocontraction and GTPՃS-induced vasocontraction were not additive. NaF-induced vasocontraction at pCa 7.0 was inhibited by pretreatment with Rho kinase inhibitors H1152 or Y27632 but not with a MLCK inhibitor ML-7 or a PKC inhibitor Ro31-8220. NaF induces calcium sensitization in a Ca^2＋- dependent manner in Ղ-escin-permeabilized rat mesenteric arteries. These results suggest that NaF is an activator of the Rho kinase signaling pathway during vascular contraction.