The effect of hydrocortisone on neurons acutely isolated from the rat airway parasympathetic ganglia was investigated by using nystatin perforated-patch recording configuration under the voltage-clamp conditions. Acetylcholine (ACh) evoked inward currents in a concentration-dependent manner with a half maximum effective concentration (EC50) of 3.3 x 10(-5) M at a holding potential of -50 mV. The ACh response was mimicked by nicotine, and it was inhibited by both mecamylamine and hexamethonium. alpha-Bungarotoxin had no effect on the ACh response. Hydrocortisone concentration-dependently inhibited the current induced by 3 x 10(-5) M ACh with a half maximum inhibitory concentration (IC50) of 2.1 x 10(-4) M. The effect of hydrocortisone was voltage-independent. Hydrocortisone suppressed the maximum response of the ACh concentration-response curve, indicating that the inhibitory action of hydrocortisone on the nicotinic ACh response is non-competitive.