Title: Effects of $Cl^-$ Channel Blockers on the Cardiac ATP-sensitive $K^+$ Channel
Abstract: To explore whether channel blockers interact with the ATP-sensitive channel, I have examined the effect of two common channel blockers on the channel activity in isolated rat ventricular myocytes using patch clamp techniques. In inside-out patches, 4,4'-diisothio-cyanatostilbene- 2,2'-disulfonic acid (DIDS) and niflumic acid applied to bath solution inhibited the channel activity in a concentration-dependent manner with of 0.24 and 927 respectively. The inhibitory action of DIDS was irreversible whereas that of niflumic acid was reversible. Furthermore, DIDS-induced block was not recovered despite exposure to ATP (1 mM). In cell-attached and inside-out patches, DIDS blocked the pinacidil- or 2,4-dinitrophenol (DNP)-induced channel openings. In contrast, niflumic acid did not block the pinacidil-induced channel openings in inside-out patches, but inhibited it in cell-attached patches. DIDS and niflumic acid produced additional block in the presence of ATP and did not affect current-voltage relationship and channel kinetics. All these results indicate that DIDS among channel blockers specifically blocks the cardiac channel.
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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