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Voltage-gated Na⁺ channels (VGSC) are transmembrane proteins that are essential for the initiation and propagation of action potentials in neuronal excitability. Because neurons express a mixture of Na⁺ channel isoforms and protein kinase C (PKC) isozymes, the nature of which channel is being regulated by which PKC isozyme is not known. We showed that DRG VGSC Na_v1.7 (TTX-sensitive) and Na_v1.8 (TTX-resistant), expressed in Xenopus oocytes were differentially regulated by protein kinase A (PKA) and PKC isozymes using the two-electrode voltage-clamp method. PKA activation resulted in a dose-dependent potentiation of Na_v1.8 currents and an attenuation of Na_v1.7 currents. PKA-induced increases (Na_v1.8) and decreases (Na_v1.7) in peak currents were not associated with shifts in voltage-dependent activation or inactivation. The PKA-mediated increase in Na_v1.8 current amplitude was prevented …