SULFHYDRYL REDOX MODULATES ATP-SENSITIVE K+ CHANNELS IN RABBIT VENTRICULAR MYOCYTES

The properties of sulfhydryl redox modulation of the ATP-sensitive K(K-ATP) channel have been examined in rabbit ventricular myocytes, usi ng the patch-clamp technique. The sulfhydryl oxidizing agent 5.5'-dith io-bis-(2-nitro-benzoic acid) (DTNB) induced an inhibition of the chan nel activity without change in the single channel conductance. DTNB ha d no effect on the inhibitory action by ATP. Analysis of the open and closed time distributions showed that DTNB decreased the life time of bursts and increased the interburst interval without changes in open a nd closed time distributions shorter than 5 ms. N-ethylmaleimide (NEM) , a substance that reacts with sulfhydryl groups of cysteine residues in proteins, induced an irreversible closure of the channel. The resul ts suggested that changes in the sulfhydryl redox also modulate K-ATP channel activity of the K-ATP channel in rabbit ventricular myocytes. (C) 1996 Academic Press, Inc.