The characteristics of ATP-activated currents (I(ATP)) in rat nodose ganglion (NG) neurons have not been fully clarified. Especially, the correlation between I(ATP) phenotype and P2X receptor subunit genotype in rat NG neuron is not clear. By whole-cell patch-clamp and single cell immunocytochemical techniques, we explored the characteristics of the I(ATP) phenotype and its correlation with P2X receptor subunits in acutely isolated NG neuron of rats. The results indicated that I(ATP) of NG neurons can be classified into four types: F type (fast type, 8.1%), I type (intermediate type, 14.8%), S type (slowing type, 37.0%) and vS type (very slowing type, 21.5%). The single immunocytochemical studies have demonstrated that F type cells express P2X1 and P2X3 subunits, I type cells P2X1, P2X3 and P2X4 subunits, S type cells P2X1, P2X2 and P2X3 subunits and vS type cells P2X2, P2X3 and P2X4 subunits. The results reveal that there are four types of I(ATP) in NG neurons, differential expression of distinct P2X subunits may underlie the I(ATP) phenotype.