Possible Antinociceptive Mechanisms Triggered by Nanomolar Ouabain Concentrations in Primary Sensory Neurons

The responses of primary sensory neurons to subnanomolar and nanomolar ouabain concentrations, corresponding to the endogenous ouabain (EO) concentration, were studied. Atomic force microscopy (AFM) studies showed that exposure to EO led to an increase in neuron stiffness. Studies using local voltage clamping showed that ligand-receptor binding of EO with the Na,K-ATPase/Src complex decreased the effective charge of the activatory gate system of Na V 1.8 channels. Furthermore, the EO-activated intracellular cascade in which the Na,K-ATPase/Src complex operates as a signal transducer was found to lead to a decrease in the fluorescence intensity of antibodies to Na V 1.8 channels, as demonstrated by confocal laser scanning microscopy. These results suggest that EO, triggering the transduction function of the Na,K-ATPase/Src complex and the corresponding intracellular signal cascade, is able to modulate the expression of the SCN10A gene, which produces Na V 1.8 channels, which are responsible for encoding nociceptive signals.