ELECTROTONIC PROPAGATION OF KININ-INDUCED, ENDOTHELIUM-DEPENDENT HYPERPOLARIZATIONS IN PIG CORONARY SMOOTH MUSCLES

The kinins, substance P and bradykinin, cause endothelium-dependent hy perpolarizations in smooth muscles of the pig coronary artery. We test ed whether the propagation, in the media, of these hyperpolarizations is passive or whether the hyperpolarizations are regenerated in the sm ooth muscle cells. The space constants measured in response to the kin in endothelium-dependent stimulations were compared to those obtained by electrical field stimulation. The space constant is 2.6 +/- 0.2 mm (n = 13) measured for substance P and 2.2 +/- 0.2 mm (n = 12) for brad ykinin. The space constants established by electrical field stimulatio n-induced hyperpolarization are 3 +/- 0.2 mm (n = 7) for strips with i ntact endothelium and 2.7 +/- 0.3 mm (n = 7) for strips with removed e ndothelium. These results show that the space constants obtained for t he kinin stimulations are not larger than those caused by electrical f ield stimulation. This suggests that the kinin-induced hyperpolarizati ons propagate, in the media, in a passive, electronic manner, therefor e the hypothesis of regenerated kinin hyperpolarizations is unlikely.