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Enhanced effects of sulfur dioxide on voltage-gated potassium channels in rat vascular smooth muscle cells

Zhang Yang, Li Fangyuan, Suo Hui, Zhang Xiasha, Du Zhengqing

Previously we observed vasodilator effects of gaseous sulfur dioxide on rat vascular smoothmuscle cells. Themain purpose is to further investigate enhanced effects of sulfur dioxide on voltage-gated potassium channel. The results showed that sulfur dioxide derivatives significantly increased the outward potassium currents (IKV) with a certain degree of voltagedependent, 10 ìmol/L sulfur dioxide derivativesmade current-voltage curve significantly shift up. And sulfur dioxide derivatives increased IKV in a dose-dependent manner. It increased IKV to some extent after applying 5 mmol/L4-aminopyridine (4-AP).Tetraethylammoniumchloride (TEA) could inhibit the increased amplitude IKV. Moreover, 10 ìmol/L sulfur dioxide derivatives could significantly shift IKV activation curve to the hyperpolarized direction,while did not affect the slope factor. In conclusion, sulfur dioxide derivatives increased outward IKV amplitude and activated potassium currents in advance. This might be one of the mechanisms about the depressing blood pressure effect of sulfur dioxide and derivatives. TEA and 4-AP can antagonize the augmentation of potassium currents in vascular smooth muscle cells induced by sulfur dioxide derivatives