抗癌止痛肽AGAP对DRG神经元TTX-S钠离子通道的影响

Objective: To investigate the effect of AGAP on TTX-S sodium channels in DRG neurons. Methods: Immunofluorescence staining of NF200 on large DRG neurons of rats. We use patch clamp to observe the effect of AGAP on TTX-S sodium currents and channel kinetics characteristics in DRG neurons. Results: Our data demonstrated that AGAP may reduce the TTX-S sodium currents in the concentration of 30 nM and 100 nM but not in the concentration of 300 nM and 1000 nM. The maximal current density of TTX-S sodium currents on large DRG neurons was 168±22 pA/pF (n=21), which was reduced to 64±22 pA/pF (n=5, P<0.05) and 43±13 pA/pF (n=4, P<0.05) respectively after the application of 30 nM and 100 nM AGAP, with a inhibitory rate of 61.9% and 74.4% respectively. The kinetics of TTX-S sodium channel showed that AGAP significantly shifted the activation curve to the hyperpolarizing direction and changed the slope significantly. V1/2 and Km under normal condition were -37.08±0.40 mV (n=12) and 4.07±0.33 (n=12), -55.18±1.86 mV (n=7, P<0.001) and 2.99±1.04 (n=7, P<0.05) after the application of 300 nM AGAP. There was no significant shift in the inactivation curve after the application of AGAP. Vh and κ under normal condition were -51.13±0.83 mV (n=14) and 7.19±0.71 (n=14), -57.03±1.55 mV (n=12, P>0.05) and 5.69±1.32 (n=12, P>0.05) after the application of 300 nM AGAP. AGAP significantly prolonged the time constant (τ) of recovery from inactivation. τ under normal condition was 3.12±0.43 ms (n=19), and 10.91±1.97 ms (n=9, P<0.05) after the application of 300 nM AGAP.