ACETYLCHOLINE-ACTIVATED IONIC CURRENTS IN ISOLATED PARATRACHEAL GANGLION-CELLS OF THE RAT

The electrophysiological property of acetylcholine (ACh)-induced current (I(ACh)) was studied in paratracheal ganglion cells freshly isolated from rat trachea under whole-cell voltage-clamp condition. I(ACh) consisted of an initial transient peak component and a successive steady-state plateau one. The peak component increased in a sigmoidal fashion with increasing ACh concentration. The I(ACh) was mimicked by nicotine. The current-voltage relationship for the I(ACh) showed inward rectification at the positive membrane potentials beyond the reversal potential (E(ACh)). In a K+-free solution, the E(ACh) was close to the Na+ equilibrium potential. The I(ACh) was blocked by either D-tubocurarine or atropine. The ion selectivity of ACh-activated channels to various monovalent cations was weak, and similar to those of other preparations. It was concluded that the I(ACh) in rat paratracheal ganglion cells was mediated by nicotinic receptor activation.