On the molecular nature of differences in the response of sensory neurons and fibroblasts to ouabain

Atomic force microscopy was used to study under physiologically adequate conditions the effect of ouabain on the mechanical characteristics of sensory neurons and fibroblasts of 10–12-day old chick embryos. Fibroblasts express only the $\alpha$1-isoform of Na,K-ATPase, and sensory neurons the $\alpha$1- and $\alpha$3-isoforms. It was found that the action of ouabain at a concentration corresponding to the endogenous value leads to an increase in the membrane rigidity of sensory neurons, which is apparently due to the activation of the transducer function of Na,K-ATPase, rather than the pumping function. The endogenous concentration of ouabain did not change the mechanical characteristics of fibroblasts. The results obtained suggest that endogenous ouabain modulates the transducer function of the $\alpha$3-isoform of Na,K-ATPase of the sensory neuron membrane. Thus, the method of atomic force microscopy allows a comparative study of intracellular signaling cascades in living cells.