Journal
EUROPEAN JOURNAL OF PHARMACOLOGY
Volume 831, Issue -, Pages 60-67Publisher
ELSEVIER
DOI: 10.1016/j.ejphar.2018.05.006
Keywords
Endothelium; Mesenteric arteries; KCa channels; Vasodilation
Categories
Funding
- Canadian Institutes of Health Research [MOP 142467]
- Cumming School of Medicine
- Libin Cardiovascular Institute of Alberta
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It is now well recognized that endothelial KCa2.3 and KCa3.1 channel activities contribute to dilation of resistance arteries via endothelium-mediated hyperpolarization and vascular smooth muscle relaxation. In this study, we have investigated the functional effect of the KCa channel activator SKA-31 in third order rat mesenteric arteries using arterial pressure myography. Isolated arteries were cannulated, pressurized intraluminally to 70 mmHg at 36 degrees C and then constricted with 1 mu M phenylephrine. Acute bath exposure to SKA-31 evoked a robust and reversible inhibition of developed tone (IC50 = 0.22 mu M). The vasodilatory effects of SKA-31 and acetylcholine were blunted in the presence of KCa2.3 and KCa3.1 channel antagonists, and were largely prevented following endothelial denudation. Western blot and q-PCR analyses of isolated mesenteric arteries revealed KCa2.3 and KCa3.1 channel expression at the protein and mRNA levels, respectively. Penitrem-A, an inhibitor of KCa1.1 channels, decreased vasodilatory responses to acetylcholine, sodium nitroprusside and NS-1619, but had little effect on SKA-31. Similarly, bath exposure to the eNOS inhibitor L-NAME did not alter SKA-31 and acetylcholine-mediated vasodilation. Collectively, these data highlight the major cellular mechanisms by which the endothelial KCa channel activator SKA-31 inhibits agonist-evoked vasoconstriction in rat small mesenteric arteries.
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