Vasodilatory effect of Phellinus linteus extract in rat mesenteric arteries. - GreenMedInfo Summary

is a well-known medicinal mushroom that is widely used in Asian countries. In several experimental models,extracts were reported to have various biological effects, including anti-inflammatory, anti-cancer, hepatoprotective, anti-diabetic, neuroprotective, and anti-angiogenic activity. In the present study, several bioactive compounds, including palmitic acid ethyl ester and linoleic acid, were identified in. The intermediate-conductance calcium-activated potassium channel (IK) plays an important role in the regulation of the vascular smooth muscle cells' (VSMCs) contraction and relaxation. The activation of the IKchannel causes the hyperpolarization and relaxation of VSMCs. To examine whetherextract causes vasodilation in the mesenteric arteries of rats, we measured the isometric tension using a wire myograph. After the arteries were pre-contracted with U46619 (a thromboxane analogue, 1µM),extract was administered. Theextract induced vasodilation in a dose-dependent manner, which was independent of the endothelium. To further investigate the mechanism, we used the non-selective Kchannel blocker tetraethylammonium (TEA). TEA significantly abolishedextract-induced vasodilation. Thus, we tested three different types of Kchannel blockers: iberiotoxin (BKchannel blocker), apamin (SKchannel blocker), and charybdotoxin (IKchannel blocker). Charybdotoxin significantly inhibitedextract-induced relaxation, while there was no effect from apamin and iberiotoxin. Membrane potential was measured using the voltage-sensitive dye bis-(1,3-dibutylbarbituric acid)-trimethine oxonol (DiBAC(3)) in the primary isolated vascular smooth muscle cells (VSMCs). We found that theextract induced hyperpolarization of VSMCs, which is associated with a reduced phosphorylation level of 20 KDa myosin light chain (MLC).