Effect of endothelin as a coronary vasoconstrictor in the Langendorff-perfused rat heart

The effects of endothelin on coronary circulation were studied in isolated rat heart using a constant-flow system. Endothelin (10 fmol to 20 pmol/g heart weight) elevated the coronary perfusion pressure in a dose-dependent manner. Nifedipine (100 nM) inhibited the vasoconstriction and shifted the dose-response curve to the right. These results indicate that endothelin is a potent coronary vasoconstrictor and that its action is possibly mediated by the nifedipine-dependent Ca2+ channel.