Objective The present study was aimed to investigate the pharmacological modulatory effects of ropivacaine,an amide-type local anesthetic,on rat Nav1.2（rNav1.2）and rNav1.5,the two Na＋channel isoforms heterologously expressed in Xenopus oocytes and in HEK293t cell line,respectively.Methods Two-electrode voltage-clamp（TEVC）and whole-cell patchclamp recordings were employed to record the whole-cell currents.Results Ropivacaine induced tonic inhibition of peak Na＋ currents of both subtypes in a dose-and frequency-dependent manner.rNav1.5 appeared to be more sensitive to ropivacaine.In addition,for both Na＋channel subtypes,the steady-state inactivation curves,but not the activation curves,were significantly shifted to the hyperpolarizing direction by ropivacaine.Use-dependent blockade of both rNav1.2 and rNav1.5 channels was induced by ropivacaine through a high frequency of depolarization,suggesting that ropivacaine could preferentially bind to the 2 inactivated Na＋channel isoforms.Conclusion The results will be helpful in understanding the pharmacological modulation by ropivacaine on Nav1.2 subtype in the central nervous system,and on Nav1.5 subtype abundantly expressed in the heart.
Objective To examine the effect of deglycosylation on gating properties of rNav1.3. Methods rNav1.3 was expressed in Xenopus oocyte, with glycosylation inhibition by using tunicamycin. Two-electrode voltage clamp was employed to record the whole-cell sodium current and data were analyzed by Origin software. Those of glycosylated rNav1.3 were kept as control. Results Compared with glycosylated ones, the steady-state activation curve of deglycosylated rNav1.3 was positively shifted by about 10 mV, while inactivation curve was negatively shifted by about 8 mV. Conclusion Glycosylation altered the gating properties of rNav 1.3 and contributed to the functional diversity.
