Levosimendan and its metabolite OR-1896 elicit KATP channel-dependent dilation in resistance arteries in vivo.
Journal Title: Pharmacological Reports - Year 2013, Vol 65, Issue 5
Abstract
Background: Levosimendan and its long-lived metabolite OR-1896 produce vasodilation in different types of vessels by activating ATP-sensitive (KATP) and other potassium channels. Methods: In the present study we applied intravital videomicroscopy to investigate the in situ effects of levosimendan and OR-1896 on the diameters of real resistance arterioles (rat cremaster muscle arterioles with diameters of ≈ 20 μm). Results: Levosimendan and OR-1896 induced concentration-dependent (1 nM - 100 μM) dilations to similar extents in these arterioles (maximal dilation from 23 ± 2 to 33 ± 2 μm and from 22 ± 1 to 32 ± 1 μm, respectively). The arteriolar dilations induced by the selective KATP channel opener pinacidil (1 nM - 10 μM) (maximal dilation from 22 ± 4 μm to 35 ± 3 μm) were diminished in the presence of the selective KATP channel blocker - glibenclamide (5 μM) (maximal diameter attained: 22 ± 1 μm). Glibenclamide also counteracted the maximal dilations in response to levosimendan or OR-1896 (to 23 ± 3 μm or 22 ± 5 μm, respectively). Conclusions: In conclusion, this is the first demonstration that levosimendan and OR-1896 elicit arteriolar dilation in vivo, via activation of KATP channels in real resistance vessels in the rat.
Authors and Affiliations
Ildikó Gödény, Piero Pollesello, István Edes, Zoltán Papp, Zsolt Bagi
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