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.

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 α1-isoform of Na,K-ATPase, and sensory neurons the α1- and α3-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 α3-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.

Using atomic force and confocal laser scanning microscopy, we studied the effect of colchicine, 1 µg/ml, which is known to cause the depolymerization of tubulin microtubules, on the primary rat fibroblast culture. When analyzing atomic force microscopy data, the sliding type of probe–cell contact was revealed by observing a clear increase of deformation signal at the sample inclined areas. For an unambiguous interpretation of the observed variations in the mechanical characteristics of fibroblasts, it is necessary to prove the sliding of the probe over the cell surface. It was found that some fibroblasts are soft and are characterized by a quite uniform distribution of the apparent Young's modulus over their surface, while others, much harder cells have rigid fibrous structures on the Young's modulus map. Colchicine has been shown to cause significant cell hardening in both groups. Confocal microscopy data show that the observed effect is associated with an increase in the intracellular content of F-actin in fibroblasts.

Atomic force microscopy (AFM) measurements have revealed hardening of intact fibroblasts after treatment with colchicine. The reliability of AFM measurements was confirmed by the identification of cells the lateral response of which to indentation did not disturb the normal force contribution. AFM data on the mechanical characteristics of such cells admit an unambiguous interpretation.

It was found that living fibroblasts become more rigid after exposure to colchicine. For reliable measurements, we identified the cells, that during indentation interact with weak lateral forces that do not distort the normal force contribution. The atomic force microscopy data of the mechanical characteristics of such cells are interpreted unambiguously.

AbstractLiving sensory neurons were studied by atomic force microscopy in the PeakForce QNM mode under near-physiological conditions. The dependence of the measured apparent Young modulus of cells on the ratio of the probe height to the beam length on a used cantilever was revealed. A qualitative explanation based on the analysis of beam strains in two limit cases, in which the probe slides over a studied object and the probe sticks to the latter, was given to the obtained result. It was proposed to classify native cells by the character of their interaction with the probe (sliding or sticking).

Living sensory neurons were studied by atomic force microscopy in the PeakForce QNM mode under near-physiological conditions. The dependence of the measured apparent Young modulus of cells on the ratio of the probe height to the beam length on a used cantilever was revealed. A qualitative explanation based on the analysis of beam strains in two limit cases, in which the probe slides over a studied object and the probe sticks to the latter, was given to the obtained result. It was proposed to classify native cells by the character of their interaction with the probe (sliding or sticking).

In this paper, a method for determination of the diameter of spherical particles in composite medium on the basis of the Mie scattering theory using terahertz spectroscopy in the range from 0.1 THz to 1 THz was proposed.

Intact embryonic fibroblasts on a collagen-treated substrate have been studied by atomic-force microscopy (AFM) using probes of two types: (i) standard probes with tip curvature radii of 2–10 nm and (ii) special probes with a calibrated 325-nm SiO 2 ball radius at the tip apex. It is established that, irrespective of probe type, the average maximum fibroblast height is on a level of ~1.7 μm and the average stiffness of the probe–cell contact amounts to ~16.5 mN/m. The obtained AFM data reveal a peculiarity of the fibroblast structure, whereby its external layers move as a rigid shell relative to the interior and can be pressed inside to a depth dependent on the load only.

Peak force measurements with the aid of atomic force microscopy are used to quantitatively map nanomechanical properties of intact erythrocytes of rats under conditions that are close to physiological conditions. Erythrocytes that are immobilized on the substrate preliminary processed using poly-L-lysine predominantly exhibit plane shape. However, cells may also exhibit stepwise transformation to semispherical objects with an increase in volume and hardening. Possible reasons for such transformations are discussed.

The technique of atomic force microscopy allows revealing living cell morphology and mechanical properties characterization under physiologically relevant conditions. Here, we review our recent results on living cell reaction to different external influences obtained by this technique. The Bruker PeakForce QNM quasistatic mode was used to study living fibroblasts, erythrocytes, sensory neurons, and endothelial cells.

Интактные фибробласты, находящиеся на обработанной коллагеном подложке, исследованы с помощью атомно-силового микроскопа с использованием двух типов зондов: стандартных, с радиусом закругления кончика 2-10 nm, и специальных, с закрепленным на кончике SiO2 шариком калиброванного радиуса 325 nm. Установлено, что независимо от выбранного типа зонда средняя максимальная высота фибробласта оказывается на уровне ~ 1.7 mum, а средняя жесткость контакта зонда с клеткой составляет ~ 16.5 mN/m. Результат проявляет особенность устройства фибробласта, заключающуюся в том, что по отношению к внутреннему содержимому клетки ее внешние слои ведут себя как жесткая оболочка, которая продавливается зондом на глубину, зависящую только от величины нагрузки. DOI: 10.21883/PJTF.2017.04.44298.16461