Figure 7.

4-Aminopyridine and the smooth muscle cells of the guinea-pig carotid artery. Left panel: endothelium-dependent hyperpolarization of the smooth muscle cells of isolated fragments of internal carotid artery, measured with intracellular microelectrode. Right panel: voltage-gated potassium currents in freshly isolated smooth muscle cells of the guinea-pig carotid artery: presence of very low concentration of intracellular calcium for a step depolarization from −100 to 40 mV (whole cell configuration of the patch-clamp technique). 4-Aminopyridine induces a concentration-dependent inhibition of the acetylcholine-induced hyperpolarization and of the voltage-gated potassium currents.