Endothelin-1 inhibition of the ATP-sensitive K+ channel in guinea-pig ventricular cardiomyocytes

• 1.1. Effects of endothelin-1 on the ATP-sensitive K⁺ channel were examined in guinea-pig ventricular cardiomyocytes.
• 2.2. The ATP-sensitive K⁺ channel was activated outwardly with amplitude of about 2.2 pA at 0 mV. The conductance was 31 pS at 5.4 mM external K⁺ solution. The open probability was inhibited, and was completely blocked at 1 nM of endothelin-1.
• 3.3. In contrast, endothelin-3 (1 nM) did not cause any effects on the channels.
• 4.4. Endothelin-1 (10 nM) significantly prolonged the action potential duration. These responses were reversible.
• 5.5. These results suggest that endothelin-1 may reverse the physiological responses to the stimulation of ATP-sensitive K⁺ channels, indicating its regulatory mechanisms under the disease conditions.