Actions of kurtoxin on tetrodotoxin-sensitive voltage-gated Na+ currents, NaV1.6, in murine vas deferens myocytes

Kurtoxin is described as a selective inhibitor of Ca v 3.1. Using patch-clamp techniques, the modulatory effects of kurtoxin on tetrodotoxin-sensitive voltage-gated Na + currents (I Na ) recorded from mouse vas deferens myocytes were investigated. Kurtoxin increased the peak amplitude of I Na between -40 and -30 mV, whilst inhibited the peak amplitude at more positive potentials than - 10 mV, thereby demonstrating a dual action on the peak amplitude of I Na . The time to reach the peak amplitude of I Na became significantly longer in the presence of kurtoxin in comparison with that of the controls. Kurtoxin also slowed the deactivation of I Na at more positive membrane potentials than -30 mV. Kurtoxin enhanced the total amount of electrical charge of I Na in a concentration-dependent manner. These results suggest that kurtoxin is a modulator of Na v 1.6 in native freshly dispersed smooth muscle cells from mouse vas deferens as well as its action on Ca v 3.1.