On the Molecular Nature of Differences in the Response of Sensory Neurons and Fibroblasts to Ouabain

The effects of ouabain on the mechanical characteristics of primary sensory neurons and fibroblasts of 10- to 12-day-old chicken embryos were investigated by atomic force microscopy under physiologically relevant conditions. Fibroblasts express only the α1 isoform of Na,K-ATPase, while sensory neurons express the α1 and α3 isoforms. It was found that exposure to ouabain in the concentration corresponding to its endogenous level led to an increase in membrane rigidity of sensory neurons, which was apparently due to activation of the transducer rather than the pumping function of Na,K-ATPase. The mechanical parameters of fibroblasts were not affected by exposure to endogenous concentrations of ouabain. These results suggest that endogenous ouabain specifically modulates the transducer function of the α3 Na,K-ATPase isoform in the sensory neuron membrane. Thus, atomic force microscopy was efficiently applied to perform a comparative study of intracellular signaling cascades in living cells.