Activation of myocyte voltage-gated K+ channels is involved in HSYA-induced rat coronary arterial relaxation

AIM: To observe the effects of hydroxysafflor yellow A (HSYA) on the relaxation of isolated rat coronary artery (RCA) rings and its relationship with voltage-gated K⁺ (Kv) channels. METHODS: The vascular tension was recorded with a wire myograph. The Kv currents of freshly isolated RCA smooth muscle cells were assessed with whole-cell patch clamp. The protein expression levels of Kv1.2 and Kv1.5 in RCA smooth muscle cells were assayed by Western blot. RESULTS: HSYA (10 μmol/L and 30 μmol/L) led to relaxation of RCA precontracted by 60 mmol/L KCl or 0.1 mmol/L U46619 (P<0.05), but the effect showed no statistical difference between endothelium-intact and endothelium-denuded groups (P>0.05). HSYA (3 μmol/L, 10 μmol/L and 30 μmol/L) significantly increased the maximal Kv currents of RCA smooth muscle cells (P<0.05). HSYA (10 μmol/L and 30 μmol/L) increased the protein expression of Kv1.2 and Kv1.5 (P<0.05). CONCLUSION: HSYA relaxes isolated RCA in an endothelium-independent manner. The vasodilatory effect of HSYA may be related to activation of the myocyte Kv channels.