Modulation of voltage-dependent currents by muscarinic receptor in sympathetic neurones of bullfrog.

The muscarinic actions of acetylcholine (ACh) on the action potentials of bullfrog sympathetic ganglion cells were studied with voltage-clamp experiments. The slow inward current (Isi) carried by Ca2+ was markedly depressed by ACh. ACh also markedly depressed the time-dependent outward current following Isi. The outward current was composed of two components, a TEA-sensitive rectifier K+ current (IK1) and a TEA-insensitive slow rectifier K+ current (IK2). Both of these components were depressed by ACh.