Regulatory effect of Zn2+ on P2X receptor-mediated, ATP-induced currents in different autonomic ganglion neurons in rats / 第二军医大学学报

ABSTRACT

Objective: To compare the effects of Zn2+ on the P2X receptor-mediated, ATP-induced currents in neurons separated from rat superior cervical ganglion (SCG), nodose ganglion (NG), and otic ganglion (OTG). Methods: Whole-cell patch clamp recording technique was used to study the regulatory effects of Zn2+ on ATP/αβ-me ATP-induced currents in the above 3 ganlglion neurons. Results: All SCG neurons responded to ATP with a sustained current, while no neurons responded to αβ-me ATP; Zn2+ potentiated ATP-induced sustained currents to (1442±34)% of the original value. All NG neurons responded to ATP and αβ-me ATP with a similar sustained current; coapplication of Zn2+ (10 μmol/L) potentiated their responses to (180±12)% and (262±28)%, respectively. All OTG neurons responded to both ATP and αβ-me ATP with a sustained current. Coapplication of Zn2+ (10 μ mol/L) did not significantly potentiate the sustained currents induced by 10 μmol/L ATP, but when ATP was at 30 μmol/L, Zn2+ (10-100 μmol/L) inhibited ATP-induced sustained currents in a dose dependent manner. If TNP-ATP (100 nmol/L) was first used to inhibit ATP-induced current to (26±2)% of the original value, Zn2+ at 10 μmol/L potentiated the inhibited current to (127±9)% of its original value. Coapplication of Zn2+ (10 μmol/L) potentiated αβ-me ATP-induced currents to (146±5)% of the control. Zn2+ (300 μmol/L) had no effect on τon and τoff of ATP- and αβ-me ATP-induced (30 μmol/L) currents in OTG neurons. Conclusion: (1) Zn2+ is an allosteric modulator of P2X2 and P2X2/3 receptors in SCG and NG neurons and can potentiate the currents they induced. (2) The predominant receptor subtypes in OTG appear to be homomeric P2X2/3 and a little P2X2. Zn2+ has an inhibitory effect on the ATP-induced currents in OTG neurons, suggesting some novel members of the P2X purinoceptor exist in these neurons.