ISSN:
1432-1912
Keywords:
Nicorandil (2-nicotinamidoethyl nitrate)
;
Cardiac myocyte
;
ATP-sensitive K+ channel
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Effects of a vasodilator, nicorandil (2-nicotinamidoethyl nitrate) on four kinds for cardiac K+ channels were investigated in guinea pig ventricular and atrial cells using inside-out patch recording combined with “oilgate” concentration jump method. Nicorandil of 300 μmol/l failed to affect the inward-rectifier K+ channel and the Na+-activated K+ channel. The open probability of the muscarinic K+ channel, when activated by the application of GTP, was not changed by the drug. Nicorandil selectively increased the open probability of the ATP-sensitive K+ channel that was partly suppressed by intracellular ATP. The median effective concentration (EC50) of nicorandil was 74 μmol/l and Hill coefficient was 1.32 in the concentration-open probability relationship. The closing rate of the K+ channel by ATP was markedly delayed by the drug, whereas the open rate on removal of ATP was scarcely affected. Nicorandil had only little effect on this channel after run-down. It was concluded that nicorandil selectively activates the ATP-sensitive K+ channel mainly by modulating the ATP-dependent gate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00169050
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