[Effects of propofol and thiamylal on nicorandil induced ATP-sensitive potassium channel activities in cultured rat aortic smooth muscle cells].

BACKGROUND

Nicorandil, a hybrid ATP-sensitive potassium (K(ATP)) channel opener and nitrate compound, is used clinically for the treatment of angina pectoris. In the present study, we investigated the effects of propofol and thiamylal on sarcolemmal K(ATP) channels activities induced by nicorandil in cultured rat aortic smooth muscle cells.

METHODS

We used inside-out patch clamp configurations to investigate the effects of propofol and thiamylal on nicorandil induced K(ATP) channel activities.

RESULTS

K(ATP) channel was not spontaneously activated by patch excision in the absence of intracellular ATP. Application of nicorandil (100 microM) induced a marked activation of KATP channel currents, which was completely blocked by 3 microM glibenclamide, the sulfonylurea that blocks K(ATP) channels. Nicorandil induced KATP channel currents were not significantly inhibited by application of 10 and 100 microM propofol to intracellular surface. However, application of 100 and 300 microM thiamylal to intracellular surface significantly inhibited the nicorandil induced K(ATP) channel currents, with relative channel activities decreasing to 0.65 +/- 0.08 and 0.46 +/- 0.10 of control, respectively.

CONCLUSIONS

Propofol had no effect on nicorandil induced sarcolemmal KATP channel activities in rat aortic smooth muscle cells, whereas thiamylal significantly inhibited these channel activities at clinically relevant concentrations.