STZ treatment potentiates fast-inactivating ATP currents. A, Examples of fast-inactivating ATP currents in Dil-labeled DRG neurons isolated from control (left) and STZ-treated (right) rats. The amplitude of ATP currents obtained from STZ-treated rats was much larger than that obtained in control rats. B, Mean peak ATP current densities. The mean peak current density of the fast-inactivating ATP currents measured in DRG neurons of STZ rats was 2.2 times larger than that measured in DRG neurons of control rats (Con, 6.3 ± 1.5 pA/pF, n = 15; STZ, 13.8 ± 2.3 pA/pF, n = 12; *p < 0.05).